ED 259 931 AUTHOR TITLE INSTITUTION SPONS AGENCY REPORT NO PUB DATE CONTRACT NOTE AVAILABLE FROM PUB TYPE DOCUMENT RESUME SE 045 902 Thomas, Stephen G.; And Others Solar Greenhouses and Sunspaces: Lessons Learned. National Center for Appropriate Technology, Butte, Mont. Department of Energy, Washington, DC. Appropriate Technology Program. DOE/CE/15095-8 J,n 84 DE-AC01-82CE15095 38p, Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402. Reports - General (140) -- Reference Materials General (130) EDRS PRICE MF01 Plus Postage. PC Not Available from EDRS. DESCRIPTORS *Alternative Energy Sources; Climate Control; Energy; *Energy Conservation; *Greenhouses; Heat; *Solar En,rgy; Structural Elements (Construction); *Technological Advancement; Technology IDENTIFIERS *Appropriate Technology; Sunspaces ABSTRACT Solar technology systems are being studied, managed, built and offered as an effective alternative energy option. This publication presents background material for the building and operation of better sunspaces and greenhouses. Recent developments in solar technology are explained and information on solar greenhouse and sunspace is provided (in question and answer format) in these categories: (1) design; (2) construction; (3) management, maintenance, and safety; (4) horticulture; (5) construction workshops; and (6) information sources. Guidance in the identification of common mistakes in design. construction, and operation that affect performance of these solar structures is given. Suggestions to help consumers apply and utilize information on solar technology systems effectively are also included. (ML) *********************************************************************** Reproductions supplied by EDRS are the best that can be made from the original document. ***********************************************************************
Transcript
ED 259 931
AUTHORTITLEINSTITUTION
SPONS AGENCY
REPORT NOPUB DATECONTRACTNOTEAVAILABLE FROM
PUB TYPE
DOCUMENT RESUME
SE 045 902
Thomas, Stephen G.; And OthersSolar Greenhouses and Sunspaces: Lessons Learned.National Center for Appropriate Technology, Butte,Mont.Department of Energy, Washington, DC. AppropriateTechnology Program.DOE/CE/15095-8J,n 84DE-AC01-82CE1509538p,Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.Reports - General (140) -- Reference MaterialsGeneral (130)
EDRS PRICE MF01 Plus Postage. PC Not Available from EDRS.DESCRIPTORS *Alternative Energy Sources; Climate Control; Energy;
*Energy Conservation; *Greenhouses; Heat; *SolarEn,rgy; Structural Elements (Construction);*Technological Advancement; Technology
IDENTIFIERS *Appropriate Technology; Sunspaces
ABSTRACTSolar technology systems are being studied, managed,
built and offered as an effective alternative energy option. Thispublication presents background material for the building andoperation of better sunspaces and greenhouses. Recent developments insolar technology are explained and information on solar greenhouseand sunspace is provided (in question and answer format) in thesecategories: (1) design; (2) construction; (3) management,maintenance, and safety; (4) horticulture; (5) constructionworkshops; and (6) information sources. Guidance in theidentification of common mistakes in design. construction, andoperation that affect performance of these solar structures is given.Suggestions to help consumers apply and utilize information on solartechnology systems effectively are also included. (ML)
***********************************************************************Reproductions supplied by EDRS are the best that can be made
from the original document.***********************************************************************
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ment of Energy (DOE) awarded morethan 2,000 small grants to individuals,organizations and small businesses acrossthe nation to research and demonstrateappropriate technologies. Grants weregiven in the general areas of conserva-tion, solar. biomass, wind, geothermaland hydro power. In 1982, the NationalCenter for Appropriate Technology(NCAT) was placed under contract toreview final reports from each DOEgrantee to extract new ideas and otherproven concepts that could be of valuein applying appropriate technologies toenergy problems. Each chapter of thispublication has a list of selected projectsreviewed in preparation of thisdocument.
This booklet is one in a series of pub-lications that focuses on appropriatetechnologies and their application in thehome and the workplace. These publica-tions combine a qualitative assessment ofthe DOE grant projects by NCAT withthe results of current research.
Prepared By:
11.1. WA Nat .grruro sag). WV. Ar:
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DOE/CE/15095.8January 1984
CONTENTS
INTRODUCTION
CHAPTER ONE.
CHAPTER Two.
CHAPTER THREE.
CHAPTER FOUR.
CHAPTER FIVE.
CHAPTER SIX.
3
Design It Right 4
Build It Right: Construction Tips . . 12
Management, Maintenance,And Safety 18
The Living Greenhouse: A Guideto Growing Plants 24
Spreading the Word: Greenhouseand Sunspace ConstructionWorkshops 30.
What Other Sources ofInformation Are Available? 34
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ACKNOWLEDGMENTSA number of individuals contributed to the development and production of this publi-cation, including Stephen G. Thomas, John R. McBride, James E. Masker, and KeithKemble, co-authors; George Everett, editorial assistance; Evelyn Tracy, productionassistance; tans Haumberger, technical illustrator; Tom Cook, graphic design; and thestaff of the National Center for Appropriate Technology.
DISCLAIMNRThis report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United StatesGovernment nor any agency thereof. nor any of their employees, makes any warranty, expressed or Implied, or assumes any legalliability or responsibility for the accuracy, completeness, or usefulness ofany Information, apparatus. product, or process disclosed.or represents that its use would not infringe on privately owned rights. Reference herein to any specific commercial product, processor service by trade name. trademark. manufacturer, or otherwise. does not necessarily constitute or imply Its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed hereindo not necessarily state or reflect those of the United States Government or any agency thereof.
1 4
INTRODUCTION'1111111111111111111111111
Solar greenhouses andsunspaces are popular.One measure of that'popu-larity is the number ofpeople who receivedgrants from the U.S.Department of Energy's(DOE) Appropriate Tech-nology Small Grants Pro-gram. Nearly 200 of the2,200 total granteesstudied, built, managed,and improved greenhousesor sunspaces.
There are several rea-sons for this interest. Sun-spaces can provide heat .
and save energy, and theycan provide pleasant livingareas. Greenhouses canproduce food by extendingthe growing season ormaking it possible to gar-den year round. Green-houses and sunspaces alsoare a good way to demon-strate how solar energycan be harnessed effective-ly, and many alternativeenergy workshops anddemonstrations use green -.
houses as their focus.It is also possible to
build and use greenhousesand sunspaces without agreat deal of sophisticatedknowledge or skills, andthey do not have to be ex-pensive. Also, they are arelatively forgiving solartechnologythey canwork fairly well despitemistakes that might havebeen made during designor construction or that oc-cur in operation.
However, despite theseadvantages, manygreenhouses do not per-form as well as theyshould. As more and moreare built, used, and ob-served, more ways of im-provement are developed.
&IWO rThe experiences of theDOE grantees provide val-uable information forothers to use in buildingand operating better sun-spaces and greenhouses.Their experiences are thebasis for Solar Green-houses and Sunspaces:Lessons Learned.
This publication is di-vided into six major cate-gories: design; construc-tion tips; management,maintenance, and safety;horticulture; greenhouseconstruction workshops;and information sources.
Each chapter presentsbasic background materialon the topic and relevantinformation from selectedproject reports. A questionand answer format is usedto present information onways greenhouses andsunspaces can be im-proved.
Solar Greenhouses andSunspa, LessonsLearned has been de-veloped as a supplementto the existing literature tohelp prospective sunspace/
35
greenhouse owner/buildersget started in the rightdirection. It is not a.textbook, and is not a substi-tute for any of the good"how-to" greenhousekooks available.' Its pur-pose is to identify com-mon mistakes in design,construction and/or opera-tion that affect perform-ance, and provide usefuladvice to help consumersavoid these mistakes. Inessence, Solar Greenhousesand Sunspaces: LessonsLearned is a book of ex-periences designed to helpnovices apply and utilizethis technology in themost effective way.
o
CHAPTER ONE
DESIGN IT RIGHTGreenhouses and sunspaces can pro-
duce heat, produce plants, or providea pleasant living space. They can doany one of these things very well, butthey rarely do all three well at thesame time. For example, an efficientheat-gathering sunspace will withermost plants.
On the other hand, a greenhousedesigned and operated to produce anabundant variety of food won't havemuch room to relax in and won't pm-duce heat consistently enough to sup-plement a furnace. A sunspace de-signed as a living area will havemoderate temperatures that are toolow for supplemental space heatingand likely will not have enough roomfor substantial food production.
The first design step has to be todecide what the sunspace or green-house is being designed to do, takinginto account what seems desirable andpossible now, and what your needswill be one year (or 20 years) fromnow. Try to imagine all of the possibleop; °flunkies or problems. For exam-ple, a sunspace attached to a library inMississippi was designed specificallywith a vertical south wall to accom-modate a door which would permitaccess to wheelchairs. In another ex-ample, a grantee in Montana consid-ered adding a greenhouse to a seniorcitizens' center only to find that park-ing spaces and landscaping at the onlypossible greenhouse site were morevaluable to the members than a green-house would be. In this case, the bestdesign was to not build a greenhouseat all,
The sunspace or greenhouse buildershould also consider his or her neigh-bors, Neighbors will likely frown on abadly built, ugly structure emergingnext door, but they may easily acceptone that obviously fits in the neigh-borhood. If the neighbors are upset, itmay also lead to more formal prob-lems like covenants and zoning andbuilding codes specifically written tokeep "those things" out. Some ofthese regulations are difficult enough tocomply with now, so the builder shoulddo everything she or he can to simplify,not complicate. matters.
After the purpose is determined,other issues must be addressed. Dif-
Horticultural greenhouses require moderate temperatures and arenot usually effective space beaters.
ferent sunspaces and greenhouses de-mand different kinds of attention. Forexample, horticultural greenhousesfor serious plant production requiresoil, water, and lots of tending. Conse-quently, an attached greenhousewould not be desirable for someonewho travels frequently or who haswhite carpeting in the room adjacentto the greenhouse. To get the most outof a sunspace designed for heating,thermal shades may have to be pulledor other insulation may have to be putin place every night. Again, daily at-tention may not be possible, and thecosts associated with a fairly sophisti-cated, automatic control system maybe prohibitive.
Costs, in general, will also varydepending on the purpose of the sun-space or greenhouse. A living areasunspace will have to be secure, builtto !ast, and attractive'. One grantee inCalifornia found that a simple sun-space cost 1500 rather than $300,because it was attached to an officethat had to be locked and secured atnight. Horticultural greenhouses don'tnecessarily have to look as good, andthey can be constructed with sometemporary shortcuts (flexible plasticglazing instead of glass or rigid plastic,for example). However, greenhousesmay have extra costs for such things asmovable insulation and plumbing.
One key point should be kept inmind when aesigning each type ofsunspace or greenhouse. With horti-cultural greenhouses, plenty of light is
essential. Heating sunspaces need togather a lot of thermal energy. Livingarea sunspaces need to maintain mod-erate temperatures. There are a varietyof ways that greenhouses and aim_spaces can be designed to get the mostlight, heat, or liveability. These designfeatures focus primarily on how thelight is let in, how thermal storage isused, and how air movement iscontrolled.
Everything hinges on a well-thought-out master plan. Don't short-change the design. Don't take any-thing for granted. It is' cheaper todesign and re-design on paper than itis to revise plans during construction,or to modify a sunspace or greenhouseafter it is built and working poorly.Grantees at a community college inVirginia found that there was so muchinterest in their proposed greenhousethat the design was expanded and thesouth wall was reconfigured beforeconstruction to provide More roomfor biological study. But in Kentucky,the purpose of a grant project was tocorrect design and construction prob-lems discovered after the greenhousewent into operation.
The design aspects of light, thermalstorage, and ventilation are covered inmore detail in the following questionsand answers. Later chapters will lookat how light, storage, and ventilationcan be managed after the greenhouseof sunspace has been built.
4 6
QDo greenhouses and sunspaces have to face duesouth?
AMost do face south, but sometimes it can actually be better
if they don't. There are any number oftechniques and devices available tohelp the greenhouse designer be surethat a greenhouse or sunspace faces.south, assuming that it will perform atits very best with this orientation. Ac-tually a greenhouse or sunspace can beoriented within about 25 ° of duesouth and still collect 90 percent ofthe solar energy that it would if itfaced precisely south. Beyond 25 °,however, the percentage falls offrapidly and there are abundant ex-amples of greenhouses and sunspacesthat have performed poorly becausethey were sited improperly. '
Orienting the greenhouse orsunspace so it does not face due southcan be an effective way to controllight and heat gain. A slight easterlyorientation can help to gain heat in themorning and limit it in the afternoon.This orientation may be particularlyadvantageous where, in the spring andfall. some heating is needed in themorning but afternoons may be toohot.
Many prospective sites may havebuilding or lot limitations that don'tallow a greenhouse/sunspace to bebuilt quite where it should be. In suchcases, siting requires a little moreimagination. For example, a grantee in
0New Mexico wanted a sunspace buthad no southern exposure available towork with. He built a "sunspace"anyway, but on the north side of hishome. This "sunspace" uses r panel ofvertical glazing that extends above the c.
roof line of the house and does facesouth (known to architects as clere-story windows) (Figure 1.1). theamount of light entering the "sun-space" is increased by a reflectivepanel that also serves as an insulatorwhen it is closed against the glazing.This desiga works particularly well inthe Southwest, because this "sun-space" is also cool in the sum.ner. Inthe summer, the "sunspace" is used toincrease ventilation by drawing warmair from the rest of the house and ex-hausting it through a vent at the top ofthe "sunspace."
The important thing to remember isthat a sunspace or greenhouse must belocated to do what it if. intended to doand designed accordingly. In otherwords, it can be designed to accom-modate an orientation that is not duesouth, but it just won't perform like itshould if the orient:4ton and the de-sign are not coordinated properly. Asunspace that is intended to provideheat, but that cannot be located to faceapproximately south, will have to bedesigned''to compensate for the factthat less light will be coming In, by in-creasing the glazing area, for example.In some cases, a different kind of sun-space may be the solution. One grant-ee in Delaware found that the orienta-
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5 7
QUESTIONS .AND ANSWERS
tion of the existing building would notpermit a real, heat-producing attachedsunspace, so the porch was convertedto a living area sunspace instead.
The books cited in Chapter Six pro-vide instruction on siting greenhousesand sunspaces. The information theypresent can be used as a basis to modi-fy designs as necessary for sunspacesor greenhouses that cannot or shouldnot face directly south.
QCan a porch be converted,into a sunspace?
AIt was common for manylarger, older homes to be built
with sun porches, and there is noreason that an existing home cannotbe improved with the addition of asunspace today. In its simplest form, aporch can be enclosed with verticalglazing (plastic, salvaged storm win-dows, etc.) to serve as a sheltered en-tryway. This type of sun porch cutsthe force of winter winds, keeps warmair from rushing out of the house, andprovides a certa1" amount of solarheat gain. If a sun porch is constructedwell enough, the solar heat it gains canbe moved into the house through ex-isting windows and doors. Porchescan also provide the starting point formore extensive remodeling, limitedonly by the designer's imagination,physical limitations of the lot orhouse, and the money available.
To avoid problems and gain themost from the addition of a sun porch,keep two things in mind: structuralsoundness and ventilation. If a sunporch is to be used as a real heat-gathering sunspace or a plant-growinggreenhouse, be sure the existing foun-dation and structure are sound. Ther-mal storage units or planting beds canadd more weight than some oldporches can bear. Examine the exist-ing porch carefully and proceed ac-cordingly, reinforcing the porch first,if that is what is required.
Like other types of sunspaces, a sunporch may overheat in warm weather.Some portions of the glazing should beremovable or vents should be built into let hot air out in the summer. Theuse of recycled storm windows orsliding glass doors can be convenientfor this purpose if the sunspace is de-signed so that at least a couple of win-dows can be opened or removed toprovide cross-ventilation in the sum-mer. If some sort of shading andscreens are provided as well, theporch can also be a more pleasantplace to spend time In the summer.
QlESTIONS AND ANSWERS
fl Can a sunspace be added toa mobile home?
ASunspace additions to mobilehomes have proven to be an
effective way to save energy. They toocan be as simple as an enclosed entry-way or as extensive as a full-lengtlsunspace. The simple, entryway Ktspaces can save energy by bufferthe entrance from the weather. 0.sunspaces can provide a lot of heat,because the sunspace can have somuch heat-gathering volume coin -pared with the size of the mobilehome.
As a grantee in Montana discovered,mobile homes have one distinctivefeature that has to be kept in mind.The tops of entry doors are fairly highoff the ground, and this requires a sun-space design that permits the door tosw' ig freely out into the sunspace(Fi',ure 1.2). A straight, lean-to designwill not work.
Another grantee in California pointsout that a mobile home should beweatherized properly before adding asunspace. Otherwise, the heat gainedby the sunspace may just flow outthrough the, mobile home withoutmuch benefit.
Many mobile home parks or localgovernments limit the kinds of struc-tures that can be added to mobilehomes. Be sure to check beforehandto see if there are any restrictions thatmight prohibit or limit the addition ofa sunspace.
Wby is it important to takelong-term land use plans in-to account when developinga greenhouse or sunspaceproject?
AA project can end in disap-pointment if the greenhouse
or sunspace is proposed for land thatis not owned by the builders. Thelandowner and builder shoulddevelop a strong written agreement
which spells out the responsibilities ofboth parties. If the land is owned byan institution, one staff person maygrant permission to build a sunspaceor greenhouse without know Ing aboutlong term plans for the land.
In Louisiana, a student club receiveda grant to build a greenhouse on the
tversity farm. The farm is now be-. nved and the greenhouse will
save to be torn down and rebuilt on anew farm site. A food co-op in RhodeIsland received a grant to build agreenhouse as part of a communityfood center. Permission for construc-tion was given by the local university.One week after the greenhouse wasopened, the university sold the landand the greenhouse had to be dis-mantled.
QCan a sunspace or green-s house be designed for slop-
ing terrain?
It may not be as easy to buildon a slope, but if the site has
an adequate southern exposure, therecan be benefits from designing a sun-space or greenhouse to take advantageof a slope. Most sunspaces and green-houses perform better if they are in-sulated, and building into a slope canuse the earth as insulation. Or, with amore sophisticated design, the earthcan be used for thermal storage. Also,since warm air rises, building on aslope can aid in the natural convectionof heat to adjacent higher parts of thehouse.
To avoid disaster, the greenhouse orsunspace must be built into a slopethat is stable and drains away from thestructure. A grantee in Guam iesignedi greenhouse intended to stand upunder typhoon winds, and the 3reen-house was built into a slope to helpprotect it. However, during construc-tion, torrential rains saturated theslope and the resulting landslide cavedin the end wall and filled in the ex-cavation. Saturated or improperly
Figure 1.2 Sunspaces attached to mobile homes require specialdesigns to accommodate mobile home entry doors wbicb are fairlyhigh of the ground.
6 8
drained slopes car. be a problem any-where, and a grantee in Maine suggeststhat any greenhouse built into a slopeshould have some form of built-indrainage. Good drainage helps tomoderate the buildup of water in theslope and helps to move water awayfrom the greenhouse or sunspace.
Too much earth on the ends limitsthe area that can be glazed. The oppo-site might be true in the south, how-ever, where the cooling effect of theearth in the summer might be bene-ficial. The Maine grantee also notedthat either the natural Use of earth orearth berming on the end walls should,be minimized in horticultural green-houses, especially in northern loca-tions where light is at a premium forplant growth; but heat losses at nightthrough those glazed end walls willalso have to be considered.
QCan a sunspace or greenhouse be designed to workwith just solar energy?
Many people hope that theirsunspaces and greenhouses
can be designed to require no energyin addition to that from the sun. Insome parts of the country, there simp-ly is not enough solar radiation forgreenhouses mid sunspaces to workentirely that way in the winter. Inmuch of the country, totally passivesunspaces and greenhouses are possi-ble, but they must be designed verythoughtfully and carefully. However,sunspace and greenhouse perfor-mance always depends on theweather, and the very best design maynot overcome that occasional coldspell during a week of cloudy days. Airmovement is critical for both sunspaceand horticultural greenhouses.(Chapter Three presents an in-depthlook at the importance of ventilation.)Virtually any house that relies on asunspace as a heat source will benefitfrom the use of fans to move the airfrom the sunspace. Fairly simplesystems that use small fans can be veryeffective and low-cost. A grantee inCalifornia found that a large patiodoor opening onto the sunspace wasnot enough to let heat move naturallyinto the house. The installation of asmall fan did move the warm air insideand was much easier to control.
If, Oklahoma, a grantee found that anelect, lolly powered air delivery sys-tem (with heat storage) increased hiselectrical consumption slightly, butthe sunspace gained and deliveredheat so effectively that his natural gasconsumption was reduced and hisoverall energy bill was lower.
The same is true for horticulturalgreenhouses that are counted on toproduce food for income. The use of
supplemental heat sources (or sup-plemental light, in some cases) ingreenhouses can provide more flexi-bility at the design stage. This flexibili-ty is especially useful, because com-promises between heat and light areoften necessary. With supplementalheat available, more glazing can beadded, whch could result in some heatloss, in order to provide more light forthe plants.
Q What are Me advantagesand disadvantages of a two-story attached sunspace?
The main advantage is theA. main disadvantage: a tall sun-space can gather a lot of heat. If thespace next to the house is limited, asunspace can go up instead of out, andwhen well-managed, this can be veryeffective for heat gathering. The sun-space can also be designed so that itserves dual functions with the bottomhalf used to grow plants and the topfor heat.
Heat behaves the way it is supposedto in a tall sunspace; it goes up. Some-times it is hard to keep the first floorwarm while at the same time the sec-ond floor is overheating. A secondfloor deck built out into the sunspaceis an attractive idea, but it may not beespecially practical because of theoverheating problem.
To get the most from this type ofsunspace, keep these things in mind. Atwo-story greenhouse may not workwell if it depends only on natural ven-tilation and circulation. Somehow, thehot air at the top of the sunspace hasto he forced down. Several granteesreported that the best designs controlair flow with fans that force the airdown through ducts (plenums). Ple-nums work much better than justmounting fans on the ceiling.
Make sure too, that the house can beisolated from the sunspace. If an up-stairs room is totally open to the sun-space, temperatures will be stiflingduring the summer and even on somebright, moderate temperature days inthe winter. Windows or sliding glassdoors can he used to provide the feel-ing of openness and to help controlheat flow. Curtains behind the win-dows and doors can help block the sunand assure privacy.
It is also a good idea to design a two-story sunspace with zones in mind, asa Massachusetts grantee did. For exam-ple. if plants are grown on the bottomlevel. the sunspace can be designed tolet light into that portion year round,but internal shading devices can hedesigned into the top half to keep thesun out and heat down during thewarmer month..
QUESTIONS AN!) ANSWERS
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Figure 1.31.3 Tbe foundations of greenhouses and sunspaces in north-ern climates should be well insulated. This can allow the interior floorof the greenhouse to serve as thermal storage.
Should greenhouses and Sunspaces be insulated?
ATo get the most out of heatfrom the sun (or back-up heat
if it is used), a greenhouse or sunspaceshould be insulated. The only excep-tion to the insulation rule might besome commercial horticultural green-houses, especially existing ones thatare retrofitted for solar. As a grantee inMaine points out, the amount of glaz-ing in a commercial greenhouse can beso massive that insulating the founda-tion, end walls, and kneewalls willconserve only a minimal amount ofenergy compared with the heat lostthrough the glazing. However, evenlarge, commercial greenhouses canuse a combination of insulating tech-niques (night curtains, dual glazing,etc.) that may be cost-effective in thelong run. A Tennessee grantee con-verted an existing commercial green-house to solar and insulated all of thenon-glazed aria, Which resulted in a.46 percent reduction in fuel oil con-sumption the first year. The point isthat cost-benefit analyses for big com-mercial greenhouses have to be. verycomprehensive to determine the realvalue of increased insulation.
Two basic kinds of insulation areavailable, permanent and movable,and both have to be considered duringdesign if they are to work well. Perma-nent insulation may be applied tokneewalls, end walls, north walls (at-tached or free-standing), foundations,floors, roofs, and doors. Walls andceilings are commonly insulated withfiberglass batts while some kind ofrigid insulation is typically used on the
79
outside of foundations (Figure 1.3).Another option is to insulate the
glazed areas with dual-pane glass,layers of plastic glazings, or somecombination of these. However, asone grantee in Maine found out; toomany layers of plastic glazing (in hiscase, three layers) on a greenhouse cancut out a lot of sunlight, Remembertoo that different glazing materialsfilter out different kinds of solar radia-tion and will have different effects onplants or heat production.
Movable insulation can be very ef-fective, but this is perhaps the area ofdesign that is least developed. A grant-ee in Kansas hoped to develop an in-sulating shutter design of moderatecost, that was not too cumbersome,with a snug fit, that could also reflectlightto no avail. Movable insulationcan consist of rigid panels or insula-ting curtains or shades. The main ob-jection to almost any form of movableinsulati..1 is that it takes effort to useit. Rigid insulation can be put in placeeach night and taken down each dayand stored, or it might be designedwith hinges or slides so that it can bestored more-or-less in place. Curtaininsulation can be installed to be drawnmuch like curtains in the house.
The important thing is to thinkabout insulation during the designstage so that managing the insulationwill be as convenient as possible oncethe greenhouse or sunspace is built.Insulation than is installed as an after-thought rarely seems to work verywell.
The books referenced in Chapter Sixprovide additional information on in-sulation strategies and materials.
QUESTIONS AND ANSWERS
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Movable insulation can be closed at West to reduce beat loss tbrougb the glazing.
What is the best angle forthe glazed south wall?
AThe rule of thumb is to add10 ° or 15 ° to the site latitude
to get the angle of the glazed wall suit-able Mr maximum wintertime heatproduction. So if a sunspace or green-house is built at 45 ° north latitude, thesouth-facing glazing should be slopedat a 55° to 60 ° angle.
However, the final selection of the"best" slope for the glazing dependson the purpose of the. greenhouse orsunspace and any site limitations.Heating sunspaces are normally de-signed with the slope that lets thesun's rays pass through it as close toperpendicular as possible during themiddle of the winter. However, theuse of the optimum winter slope mayalso lead to overheating in the sum-mer, as several grantees found out.
The glazing details of horticulturalceenhouses vary more, because light
rather than heat gain is the primaryconcern, and there are several waysthat light levels can be increased. Forexample, glazing can be added to theeast, west, and even north slo..s.(Chapter Four presents other ways toincrease light levels in horticulturalgreenhouses.)
One grantee in New Hampshirefound that vertical glazing workedvery well, because so much light was
reflected from the snow during thewinter. Vertical glazing can be usefulin other cases, too. If space is Lim 'tee,and as a conseqttence the angle of theglazing is limited, more sunlight canbe let in by increasing the glazed area.
Vertical glazing is also easier tomaintain, leaks a lot less, and maystand up better because snow and rainrun off more easily. Vertical glazing isalso easier to keep clean. Water leak-age can be a problem when windowsthat open are installed on a slope, butthese windows are generally weathertight when installed vertically. Forthese reasons, vertical glazing is a
popular choice for sunspaces andgreenhouses.
Should glazing panels becurved or flat?
ADesigners have been intriguedwith both convex and con-
cave curved glazing panels (Figure1.4). The main advantage was thoughtto be that they would shed water andsnow better than flat glazing. How-ever, as several grantees discovered,the use of curved glazing creates moreproblems than it solves.
First of all, most flat glazings shedrain and snow as well as curved glaz-ings do. Curved glazing requires amuch more complex mounting designon the ends than flat glazing does.
8
Curved glazing is difficult to install,because it has to be stressed, held atthe proper curve, and then, fasteneddown. This procedure is not simple,anti many plaitic glazing materials donot curve evenly. F ecause they areunder stress, these panels are alsoharder to fasten down securely, andleaks can result.
The problem with leaks is com-pounded by the fact that curved glaz-ing tends to move more than flat glaz-ing does in response to temperaturechanges and wind. This movementworks against the fasteners, whichloosen up and allow the glazing togap. In high winds, curved glazingmay pop so that its curve is reversed.This kind of stress is likely to damagethe glazing sooner or later.
Q Now should greenhouses andsunspaces be designed forsnowy areas?
AA snowfall on the greenhousecan be delightful, irritating, or
catastrophic. In Massachusetts andMaine, grantees had problems withsnow piling up and covering the glaz-ing. And in Nebraska, a manufacturedgreenhouse collapsed under a load ofsnow.
Greenhouses and sunspaces shouldbe designed to support the heaviestexpected snow loads. One way to get
to
enough support is with larger dimen-sion lumber. However, bigger sup-ports cast bigger shadows. Perhaps theeasiest way to design a greenhouse orsunspace to minimize sno t problemsis to increase the slope of the glazedsurface. The steeper the pitch (anothercase for vertical glazing), the quickerthe snow will slide off, if it builds upat all.
There has been some speculationthat wow will not slide off of multipleglazing as quickly as it will from singleglazing, but experience Indicates thatthere is little correlation. The theorywas that the snow would melt fasteron a single glazing, the _water wouldact as a lubricant, and F'ge snow wouldslide off. It appears, however, thatgravity has more to do with it thanmelting, and when snow builds up toa certain level, its own weight willslide it off.
Using a higher knecwall h:ts beensuggested as a way to combat snowbuildup (Figure 1.5). Knee-6.111s are amixed blessing, however. They shouldbe at least two-feet high to be effec-tive, but if they are not glazed, theycan cause shading and may trap coldair.
One other solution to the snowbuildup problem that has proven ef-fective is a snow shovel.
Q.How can greenhouses andsunspaces be designed tominimize moistureproblems ?.
A Moisture can create problemsin greenhouses. and sunspaces
whether it is trapped inside or comingin from outside. Too much water fromeither source can lead to structuraldamage to the greenhouse or sunspaceand sometimes to an adjoining house.Later chapters will deal with variousmanagement techniques that can beused to cope with moisture on the in-side, but one design rule, especiallyfor. horticultural greenhouses, shouldhe noted here: horizontal greenhousestructural pieces should not be flat.Any flat surface will gather a certainamount of water, and this can eventu-ally cause wood to rot and metal torust through. Make sure sill plates andother structural surfaces are bevelled(Figure I 6).
Condensation on the inside is themost obvious and frequent concern,but water coming from outside cari bejust as troublesome. In many parts ofthe country with high rainfall levelsand/or high ground water, drainsshould he installed to take water awayfrom. the greenhouse or sunspace. Agrantee in Vermont discovered thatwater was standing in the greenhouse
112 Battens
QUESTIONS AND ANSWERS
KalwaIN Glazing
Mount) andSpacing Stdps
1x2 Battens WeatherableGlazing
1x2 SpacingBattens
s.
CURVED GLAZING AS BUILT
2 Layers of 1 mil.Teflon°, Glazing
2x4 or 214 Rafters
FLAT GLAZING ALTERNATIVE
Inner GlazIngs
Figure 1.4 Grantees discovered tbat curved glazing was,d(fficuIt towork with and often not wortb the trouble.
Ktigo"L`
Figure 1.5 Greenbouses and sunspaces can be designed with a knee-wall to belp reduce snow loading on the glazing.
Puddling of MoistureOccurs on FltiSurfaces. This MoistureSeeps Into Cracks,Causing Damage.
FLAT SILL
Moisture CondensationRuns Off SlopedSurfaces. This PreventsSeepage into Cracks.
BEVELED SILLAND PLATE AND PLATE
Figure 1.6 Sill plates and otber structural components sbould bebevelled to permit moisture to run ofj
9 11
QUEsTr3NS AND ANSWERS
during construction. As a result, atrench was dug around the green-house md perforated drain pipe, bed-ded in pea gravel, was installed to pro-vide drainage. As a North Carolinagrantee pointed out, good drainage isespecially important for greenhousesthat are partially below grade, earth-bermed, or built irto a hillside. Gut-ters also help to Ltov. water awayfrom the greenhouse.
If greenhouses have concrete orother solid surface floors, plans irmstinclude a properly sloped. built -ii:.floor drain. Floor drains no i also be agood idea in horticultural greenh.Jusesthat use a lot of water, even if the flooris made of gravel or some other por-ous material.
Q.Do greenhouses and/or sunspaces qualify for the Fed-eral solar energy tax credit?
AIt depends. In order toqualify, a solar energy collec-
tion system must consist of the follow-ing components: a solar colleoionarea (i.e., a large area of material trans-parent to solar radiation); an absorber(a surface exposed to solar radiationwhich absorbs the radiation and con-verts it to thermal energy); a storagemass; a heat distribution method; andheat regulation devices. A greenhouseor sunspace obviously contains most ifnot all of these components. But theInternal Revenue Service his alsoruled that solar energy equipmentwhich serves a dual purpose does notqualify for the tax: credit. Thus, green-houses and sunspaces are usually ex-cluded. However, components (heatdistribution, thermal storage, etc.) butnot the greenhouse or sunspace itselfmight qualify. Some individuals whohave designed their sunspace only as aheat producer and do not use thespace for any other purpose have qual-ified for the full tax credit. Since eachcase is different and depends almostentirely on the design of the green-house/sunspace, you must contact theInternal Revenue Service for more information. But, it is probably wise notto plan on receiving the tax credit.Many states also have solar energy taxcredits for which your greenhouse orsunspace may qualify.
A south-facing porch can often be converted into a sunspace.
10
12
GREENHOUSE AND SUNSPACE DESIGN Mow
Waste DOS Re$10t1 XJohn Collate DOR Mot No. Dll-FG51491000013Fairbanks, AX :-ATMIS 1Ds AX-79-001
bar beat in a greenhouse near: Fairbanks, AK Is used to hest die all rather thanbeing vented. Mot air in the greenhouse apes is blown thr t radiators giving upheat to arrantifrecte solution, ethylene glycol. The solution is plumped throtigly3/4"plastic pipe a 4 levels lathe soil (14; 11, 22 & SP). lob its the ftift system irea potential problem. The use of ethylene elycOl (toxic) will y the plants.r r the leskpinpointing the trouble spot for (pick repair. Overall energy savingsre estimated at 3119i. -omatoes natured 10-.14 dayi earlier than ones in a controlcenhouse. Total yield is reported to be 10-1S% greater than: the control.
. ,
.,-,tar greenhouse and wood heated ,:'''':iitit li liegion-11 .
residence with sublooriatcrirock ther . DUE Grant No. DE 4G42-701205064
D avidAIMS 1I4 NJ-71-009 -...
s
Belle Mead, l!0 ... .:. .
The final report describes details of ConitinctiOn and monitored results of the int-formance of a waterkock thermal storigehitem. Stange is belOw the floa Or thehouse and below the floor of an attached solar ginesBowe. The water Mange iscoupled to a wood stove Via piping under the have. Under the greenhouse the rockstorage is coupled Os an *airgear collector spites°. FierfOrMincle was repOrted tobe good and no backlit, heat was required in this NO* JeraY 'house.
Demonstration for an advanced solar DOR Region Vwith a water ceiling DOE Grant No. DR-FG024011,10122
irEnvironmental Resew& auttitute of ATM_ S Mg 141-71-006Michigan .
Ann Arbor, MlA water call was added to a pre-exkting solajtorenbouse with movable night
time insubtion/ ytime reflector in Ann Atha, Mt The water ceiling retards daytimeoverheating and additional thermal IRONIC The water WIWI caused nonoticeable in OM or minus** rate for non - flowering plants, butdelayed maturation and slightly diminbhed yield for flowering plants was reported.Algae problems were reported and addressed.
Commercial enhonse retro* protect DOB Region IVNancy L. Whitehead DOR Grant No. DRIG44-8011410244Strawberry Plains, TN ATM1S 1D1 TN-80.012
A commercial quonset-type gteebhouse was retrofitted with insulation and waterstorage In Strawberry Plains, TN. Two White of headboard insulation was added tothe northern third of the greenhouse's arch. The doors, east and west walls, and thefoundation wimem were insulated. For heat storage, 120 55.gallon barrels of waterwere ad*d under the planting beds end along the north wall. The retrofittedgreenhouse reportedly used 46% less fuel oil.
CHAPTER TwoILD IT RIGHT
ONSTRUCTION TIPSBuilding a greenhouse or sunspace is a major project.
Even the smallest, simplest greenhouse requires thoughtfulplanning and careful construction if it is to perform as itshould. Others, such as a two-story sunspace addition to anew home or a school greenhouse that is a studentlaboratory, obviously must be built very well.
To be successful, the first step of construction happensduring design. Good builders think about the sunspace orgreenhouse construction process as they develop the plan,which includes both planning for the building materials,and the construction process itself: the necessary labor,tools, etc. Obviously, some things can't be controlled, likethe weather, but the builder can plan to work in the sum-mer rather than in the winter. It is precisely because somethings cannot be anticipated or controlled that it is sonecessary for the builder to control the things that he or shecan.
Sever2l building skills may be required to build agreenhouse or sunspace: excavation, concrete work,carpentry, glazing, electrical work, plumbing. Most ofthese skills are directly transferrable from general construc-tion, but some, like glazing installation, may require somespecial techniques for sunspace or greenhouse applica-tions. As severel grantees found out, if you are not ex-perienced, some tasks are not as simple as they appear tobe. Sometimes it is much easier and ultimately less expen-sive to hire a qualifled person to do some of the work.
Even though there are a variety of tasks involved ingreenhouse or sunspace construction, one word applies toeach of them: QUALITY. Greenhouses have failed spec-tacularly because they were built with poor materials orpoor workmanship. The cheapest greenhouse demands acertain commitment of money and time. If you can't affordeither of these, you probably cannot afford to build. Asunspace or greenhouse that is built properly two yearsfrom now will be much more productive and rewardingthan one built poorly right away. And just think of thevalue that can come from an extra year of thought andplanning.
Attention to detail is essential for quality construction.Some details are bigger than others, but every one is impor-tant. A grantee in Georgia built a wooden floor (thermalstorage was not a priority in this case) for a sunspace addi-tion. The floor joists were spaced unevenly, and conse-quently standard-sized insulation did not fit between thejoists. As a result, the task of insulating under the floor wasa time-consuming and frustrating process, a process whichshould have been fairly straightforward.
Joining wood components is a detail that is essential forbuilding a good greenhouse or sunspace. One way toreduce the threat of moisture damage is to build good, tightjoints in the framing. As a result, the whole structure ismore solid and less prone to leaks, and helps to keepmoisture out of the wood. Building good joints takescareful measurement and good saw work, relatively simple,but critical tasks.
The questions and answers that follow address some ofthe most common construction problems and ways thegrantees learned to deal with them.
12 14
QWhy is it important to consult with codeinspectors when building a greenhouseor sunspace?
ABuilding codes are drawn up to ensure that astructure won't collapse, or be a fire hazard, or create
unhealthy living conditions. Such codes are meant to pro-tect life, health, and safety, and not to prevent people frombuilding. In many cases, the people who administer thesecodes can provide a great deal of Mood advice. The buildershould keep these things in mind; ii vill make relations withregulators much more cordial and productive.
'Several grantees experienced lengthy delays, because theirgreenhouses or sunspaces had to be redefined or redesignedto meet code requirements. There may also be additionalcosts associated with code-approved materials and construc-tion details. It makes good sense to find out what these re-quirements are early in the planning process.
In Connecticut, a project did not meet the setback regula-tion (the distance a structure must be set back from the lotline), causing long delays in getting the site approved. Aretrofit on a school in Connecticut experienced a 7-monthdelay as project organizers dealt with the special fire andbuilding codes for schools. In Oklahoma, a rooftopgreenhouse just didn't fit into any convenient code category.It was finally defined as a penthouse, and as such was issueda building permit. Another Connecticut grantee found(probably for the best) that his rooftop greenhouse couldnot be permitted, because the building was not strongenough to safely support the weight of a greenhouse.
In California, one grantee had to receive code variancesfrom four separate local, county, and state agencies withjurisdiction over earthquake codes before a building permitwas granted. Because the standards for the glazing materialand attachment details were so strict, the grantee had to useprofessional labor for construction instead of volunteerworkers.
Are there special things to keep in mind whenattaching a sunspace or greenhouse to anexisting building?
ATwo things seem to be most important: keep-. ing the sunspace/greenhouse square, and keeping
moisture out of the existing structure.It is rare to find an old building that is perfectly square,
and some newer ones are not much better. The first step isto determine if there is anything about the existing buildingthat will prohibit or seriously affect the sunspace orgreenhouse addition. If some parts of the old structure aregoing to bear the weight of the greenhouse or sunspace, findout if they are sound enough to do the job and if they arein the right places. If these structural parts aren't quite right,det, rmine what has to be done to make them right. All ofthis assessment takes careful measurement. Don't assume thatthings are as they appear to be. The top of one window maybe an inch or two higher than the one 8 feet away, resultingin a greenhouse that is out of square if the windows areused as a level. Also, make sure that there aren't any hiddensurprises, like a brick chimney in the wall where the sunspacor greenhouse was to he attached, or a shallow drain linewhere the foundation was supposed to be.
A greenhouse or sunspace must be built on a sound foun-dation, and that is the place to start getting things square.Once there is a level foundation to work from, thegreenhouse/sunspace will have to be adapted to the uniquemeasurements of the existing building. Shims (pieces of
QUESTIONS AND ANSWERS
wood or other materials used to build up or level surfaces)arc an integral part of the process of matching the oldbuilding and the new structure. A grantee in Pennsylvania,whose rehabilitation of an old house included a newgreenhouse, found that he was kept busy making and inser-ting shims to make the construction come out square. Justremember that shims are a finishing device, however, andnot a substitute for load-bearing structural components.
Some moisture coming through vents, doors, and win-dows from an attached greenhouse into the living space isfine. But too much moisture from greenhouses can damagethe structure it is attached to if it is allowed to saturate thewood, insulation, and sheet rock or plaster in the walls. Ifa greenhouse or sunspace addition involves a major renova-tion of the wall it is joined to, it is probably wise to takeadvantage of the opportunity to add some kind of plasticvapor retarder on the greenhouse/ sunspace side of the wallduring construction so that moisture will be kept frompassing into the wall. If the wall is left intact, thegreenhouse side should be caulked thoroughly and thensealed as tightly as possible with some kind of paint orother finish that stops moisture.
What are the best building materials to use?
AA durable greenhouse or sunspace must be builtwith good quality materials, which may require
more money up front. But good materials will save money'in the long run.
When selecting glazing materials, the primary criterion ishow they transmit solar radiation. But don't forget the otherconsiderations. Polyethylene glazings are temporary. Theymay work very well temporarily, but think about the laborand money required to replace them every year or so. Thereare some very good rigid plastic glazings, but generally theydon't last forever either, and some of them tend to discolor.Cheap glass isn't necessarily a bargain either when you thinkabout things like hail storms and vandalism. Tempered glassis best, and in some cases, safety glass may be necessary; butthen cost is a factor.
There are several points to keep in mind when usingtempered glass. Tempered glass comes in standard sizes. Ifirregular sizes are required, the glass will cost more, so designaccordingly and plan to wait a little longer for speciallyordered glass. The use of tempered glass may require evenmore care during design and construction, because temperedgloss cannot be cut at the job site. Replacement glass forsliding patio doors is a good choice, because it is tempered,double-glazed, and comes in standard sizes. "Seconds" aresometimes available at discount prices.
Wood materials for framing can be preserved to last a longtime, but some naturally last longer than others Redwoodand cedar are common choices because they are attractiveand durable. Untreated or lightly treated pine and fir can lastas little as five years in a greenhouse, but cypress is knownto have lasted for 150 years in wet environments. When us-ing any wood in a greenhouse, it is wise to seal the cut ends.There are several primer/sealers good for this that dry quick-ly; boards can be cut, sealed and assemb.ied without waiting.
Another common group of materials is known as fasteners:nails, screws, nuts and bolts. Only hot-dipped, galvanizednails hold up well enough for permanent greenhouse use,and screws, nuts and bolts should be made of brass,aluminum, or stainless steel, especially for use with redwood.Raw or poorly treated steel will deteriorate quickly in theacid present in redwood.
13 15
QUESTIONS AND ANSWERS
Q. Can recycled materials be used in a greenbouse?
AUsing recycled materials is as good an idea whenbuilding greenhouses and sunspaces as it is in
general, as long as the materials are of adequ^.te quality.Bricks, blocks, or stone make very nice floors, walkways,or planting bed supports (and add some thermal storagecapacity), and, if they are even and sound, will work wellfor foundations and walls. Several grantees indicated thatfirst-rate salvaged lumber is generally available. Reclaimedwindows can be used, too, but remember that old glass ismore brittle, and the quality varies. It may be best to usethis glass. on end walls rather than for the south glazing.
A grantee in Kentucky, who made extensive use ofrecycled materials, found that old materials are like oldhousesthey are not often true. Builders should beprepared to make changes and compromises during con-struction when using recycled supplies because the "fit"may not be exact.
Q. Are foundations difficult to build?
AMany people who have never laid blocks orworked with concrete think anyone can do it.
Grantees in both North Carolina and South Carolina reportotherwise. Foundations are just thatthe foundation for thewhole sunspace or greenhouse. Consequently, they have tobe done right, and it is not easy to build a strong, level foun-dation that has the critical job of supporting all that weight.A grantee in Delaware was able to do the masonry work,but it took much longer than anticipated to get it right.
Actually, foundation problem! can start earlier withanother seemingly simple task, site preparation and excava-tion. Several grantees found that it was possible to do theirown excavation, but they were surprised at the time andlabor it took to get the job done. Again, it may be smarterto leave excavation and masonry work to qualified contrac-tors who can do a better job more quickly.
Q. Is it bard to put up glazing?
Yes. Grantees found that installing glazing thatwouldn't leak was the most challenging construc-
tion task. Plastic glazings are somewhat easier than glass towork with, but they have their own problems.
Flexible plastic glazings can be torn or cut and it is notalways easy to secure some types in place without tearingit in the process. It is very important that these glazings besound when they are installed. Any tear or weakness is like-ly to spread, because the flexible plastic glazings move inthe wind, when ventilator fans are working, or even whendoors are opened or closed, all of which stress the material.
Most rigid plastic glazing is, in fact, not rigid, whichbecomes obvious when it is being installed and tends to sagbetween the rafters. To keep the glazing relatively even asit is being installed requires support and this task is notalways simple. The slope of the south glazing also makes in-stallation more awkward.
Structural support is also a problem when installing glass.The combination of the weight of glass and the angle of in-stallation makes this work difficult. There is always a cer-tain danger involved when working with glass, and the taskrequires enough people who are strong enough and handyenough to do the work safely.
Glass work is a task that may best be left to experiencedglaziers. However, if glaziers do install the glass, make surethat everything is ready when they get there. Otherwise,you will end up paying them to watch while you work.
14
Q What should be caulked?
AAlmost any crack. The glazing gets the mostcaulking, because it is the area that most often
leaks, Glazing should be caulked wherever it is butted oroverlapped. A grantee in Milne pointed out that thefasteners for the glazing should also be caulked. Silicone isusually the preferred caulking compound, because itadheres well, is strong, stays fairly flexible, is moisture-resistant, and lasts a relatively long time.
Caulking is done to keep moisture out and reduce in-filtration, so any, crack that can't be painted closed shouldprobably be caulked. - Caulking the cracks is especially im-portant where the moisture from the greenhouse might getinto an adjoining bulding, or where water from the.outsideleaking in might be a problem.
c:.4r.!/-
.)SV,re-c, 'X p.:4
Laying a proper foundation is one cif the most ing-,portant aspects of construction. Many granteesfound that it was more effective to hire a profes-sional than to attempt it themselves.
1'
Ft 0
Glazing is not a simple task. This greeteboueedeveloped numerous teaks arotenst the glazing andbad to undergo costly repairs.
16
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QUESTIONS AND ANSVMS
It's a good idea to thoroughly caulk your greenhouse or sunspace to help prevent air and water leaks.
Q Hoii) does the weather affect construction?
ABad weather is a common cause of constructiondelays, and grantees from all over the country were
set back by bad weather. About the only thing to do is toconsider the possibility that the weather might not be goodwhen it is supposed to. be and develop an alternativeschedule. Work should also be scheduled to avoid seasonalbad weather. A grantee in Vermont wasn't able to glaze thegreenhouse in the fall, and the greenhouse frame stoodhalf-finished through the winter,
Bad weather can be damaging as well as irritating. InMichigan, Kansas, and Utah, grantees had greenhouses vir-tually destroyed by bad weather while they were underconstruction. A greenhouse in California was damagedwhen rain bowed the rafters. To minimize weatherdamage. make sure the Job site is as secure as possible anytime work stops. It is a good idea to plan ahead for ade-quate work and storage space. Some work can be done in-side if space is available, and materials should be stored in-side when possible or protected from the elements if theyhave to be left out.
Another lesson that a California grantee learned was thatwork shouldn't be done in spite of the weather. It is onlynatural to want to get the job done, but in the Californiacase, some of the caulking was done in the rain. As a result,the caulking did not adhere properly, and the whole caulk-ing lob had to he re-done.
Q 110u, long does it take to build a sunspace orgreenhouse?IALonger than expected. Almost all of the granteeshad to spend more time than anticipated to build
their greenhouses or sunspaces, frequently leading tofrustration and increased costs as well. Some grantees ad-vised calculating the proposed labor requirements and thendoubling it. Such estimates may be a little extreme, but thepoint is that the time requirements should he analyzed ascarefully and accurately as possible. Then, a cushion of
15
time, say 10 to 26 percent, should be added to the totaltime estimate for good measure.
The time it takes to build a greenhouse or sunspace variesdepending on many factors: weather, skill of the builders,delivery of supplies, delays in contracted labor, etc. Someof the most ambitious projects were workshops. In somecases, with good organization, a simple design, and lots ofworkers, greenhouses were almost completed In two days.Howeven, in many of these cases, it took weeks or monthsto get the greenhouses really finished. The labor for agreenhouse with 800 square feet of floor area in NorthDakota was carefully recorded, and the work took a totalof 900 person-hours. A greenhouse in North Carolina tookone year to build, and others took even longer.
QWhat problems can arise when using contrac-tors on greenhouse or sunspace projects?
During the construction season, contractors oftenAs have several projects underway at the same time.Any delays caused by project sponsors or resulting fromproblems getting materials, bad weather, or the contrac-tor's other work will cause the construction schedule tochange. These schedule changes can adversely affect anyother contractors involved in the project.
In Rhode Island a grantee took more time to remove anenormous dead elm than originally had been anticipated.Consequently, the excavation contractor was not able todo his work when originally scheduled and had toreschedule it for a much later date. In Vermont, a glazingcontractor had numerous other priority projects whichcaused extensive delays in the grantee's sunspace addition.
Underestimating the costs of contracted work whenpreparing a greenhouse or sunspace project is also a prob-lem. Grantees in Connecticut planned to attach a green-house to a school. After the proposal was funded, thegrantees discovered they could not find a contractor withsolar greenhouse experience who could bid the job at therate established in the grant. It is important to negotiate anestimated cost for the contracted service before acquiringthe funding.
17
QUESTIONS AND ANSWERS
ryyL
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Always plan carefully when using contractors.Scheduling problems can cause long delays in proj-ect completion because contractors are usually verybusy during the construction season.
16
QHow can the availability of materials affect theconstruction sequence?
AGreenhouses and sunspaces are becoming morecommon, but the special materials needed to build
them are not always available in local stores, and materialssometimes must be ordered from suppliers outside the area.Two problems may result. First, several grantees reporteddelays in receiving materials. For example, a Marylandgrantee waited over four months for fans and thermostatsand a Massachusetts grantee reported that it took a longtime to acquire the proper lumber needed to build thegreenhouse. Second, some grantees received materials thatwere damaged, especially shipments of greenhouse kits.
it is Important to determine what warranties andguarantees cover materials, before they are purchased.Nebraska grantees had trouble getting satisfaction whentheir manufactured greenhouse collapsed in a storm.
Special materials needed for sunspace or green-house construction are not always available in localstores. Order well in advance so that they areavailable when needed.
18
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Just as it is important to know whata sunspace or greenhouse is expectedto do before you design and build it,. itis also important to realize that thepurpose of a greenhouse or sunspacewill dictate how it must be managed.A sunspace used primarily for spaceheat should maintain highertemperatures and lower humiditylevels than a horticultural greenhousebecause the major goal is to transfer asmuch heat as possible to the interiorliving space. For horticulture, moreheat should be retained in thegreenhouse to promote plant growth.
The chief management concerns in-volve temperature, air flow, light, andhumidity. Thermal storage is critical tominimize temperature fluctuations inhorticultural greenhouses and passivesolar sunspaces. Energy is stored inmaterials such as water, masonry, orrocksmaterials capable of absorbingradiant so.Ar energy and releasing ther-mal energy. At night and on cloudydays when direct solar energy is notavailable, heat stored in these materialsis released in the greenhouse orsunspace.
In many greenhouses and sunspaces,overheating is a problem. Generally,overheating is caused by not enoughthermal storage, by too much or im-proper glazing, or poor air movement.Even in mid-winter, improperly de-signed or managed greenhouses andsunspaces can be too hot on sunnydays, and some cooling may be requiredon most days in the spring, summer andfall.
Humidity levels especially in hor-ticultural greenhouses also may have tobe regulated both during the summerand winter. Generally, the best levelsof greenhouse relative humidity areabout 55 to ^5 percent. (Relativehumidity is a measure of the amount ofmoisture in the air compared with thetotal amount the air can hold at any par-ticular temperature.) At relativehumidities above 75 percent, mold,disease, and pest problems increase.However, the desirable relative humidi-ty for a greenhouse is significantlyhigher than that recommended forhouses, so warm air ducted from an at-
liffective. sunspaces and greenhouses are usually designed to do 071tthing tvell.in this case it's space beating.
tached greenhouse into a home cancause moisture problems. Unexpectedcondensation inside the house could in-dicate that the air from an attachedgreenhouse is too humid.
The high moisture levels commonlyfound in horticultural greenhouses canalso lead to both maintenance and safe-ty problems. With high humidity levelsand water everywhere electricity can bea special problem.
Safety and maintenance, in general,are critical considerations to themanagement and enjoyment of anygreenhouse or sunspace. Yet, becausegreenhouses and sunspaces are arelatively new phenomenon, notenough thought has been given to safe-ty and maintenance procedures.
Proper and safe management is notcomplex. But, from the experiences ofgrantees, it is clear that it's easy to makemanagement mistakes that take all thefun out of owning and operating agreenhouse or sunspace.
A greenhouse or sunspace cat: bedesigned just right and constricted
18
without a flaw. But unless thetechnology is managed and used pro-perly, performance can be disappoint-ing. The answers that follow addressseveral common questions relating toa :ariety of management concerns.
20
QWhat materials can be usedto store thermal energy?
ABesides water and rock, soiland masonry are the most
common thermal storage materials.Water can store the most energy perunit volume, nearly three times that ofrock or masonry. The 55-gallon drumseems to be the universal waterstorage container. They are so popularthat some dealers now charge as muchas $20 for a used oil drum. Do notassume that 55-gallon drums can behad free for the asking.
Deep sell growing beds in green-houses can also provide significant ther-mal storage. Even though most of thethermal storage takes place in the up-per few inches of the bed, they can con-tribute as much as 20 percent of thetotal storage capacity of a greenhouse.
Rock and masonry thermal storage ingreenhouses and sunspaces is oftenmore difficult to work with. Rock bedstorage usually requires duct work, fansor blowers and controls, and still, isoften inefficient. As a result, rock bedstorage can be expensive. Washed riverrock or crushed gravel is commonlyused on the floor of horticulturalgreenhouses, and it is highly recom-mended for drainage purposes. Butdon't count on gravel floors as a ther-mal storage medium. Since warm airrises, the rocks are usually in thecoldest part of the greenhouse.
Masonry walls can store a significantamount of heat. To be most effective,they should be built of dense materials(not hollow concrete blocks), be indirect sunlight for at least one-half ofthe day, and be well-insulated from theoutdoor environment. If reflected lightis not specifically required for plantgrowth, masonry thermal storage wallsand floors should be painted a darkcolor to absorb as much solar radiationas possible.
Various substances known as phasechange materials which store thermalenergy when they melt and release thatenergy when the material solidifiesagain are also coming into use in cer-tain greenhouse or sunspace applica-tions. The use of phase change materialswas studied by some grantees, but theiruse is still not widespread. Generally,these materials can be expensive andarc sometimes difficult to obtain.
QWhat precautions areneeded when using 55-gallondrums for water storage?
AA 55-gallon drum filled withwater weighs about 450
pounds A wall of nine 55-gallondrums weighs about two tons. Filledwater barrels are permanent fixtures.Care must he taken when stacking
drums, one on top of another, to makesure they are secure and well sup-ported from below. Barrels must alsobe treated with a rust inhibitor (3tablespoons tri-sodium phosphate perbarrel), and a cup of motor oil (a goodway to recycle used oil) should befloated on top of the water In the bar-rel to reduce evaporation. It is also agood idea to leave an inch or two ofroom at the top of the barrel to allowfor expansion and contractionwater temperatures change. Also,leave the plugs (or bungs) out of thebarrels for the same reason.
What other containers canbe used for water storage?
AWater can be stored in greaseand chemical drums (make
sure they're clean before use), 5-gallonoil or honey containers, andnumerous plastic containers such asmilk jugs and 2-liter soda pop con-tainers. Most recycled plastic con-tainers get brittle with age, particular-ly when exposed to direct sunlight, sobe prepared to replace them every fewyears. Glass containers (gallon Jugs,etc.) are also suitable if the greenhousetemperatures do not drop below freez-ing and they are properly stored toprevent breakage.
Fiberglass water storage containers,in many different shapes and sizes, arecommercially available. These con-tainers are generally sturdy and can bequite stylish, but they are expensive.Early versions of these containers weresometimes prone to leaks, but the con-tainers on the market today appear toperform very well.
QUESTIONS AND ANSWERS
QHow much thermal storageis needed?
AThe amount of thermal stor-age required in a horticultural
greenhouse depends to a large extenton whether the greenhouse will be us-ed for year-round food production. Itis possible to design and build agreenhouse that is almos 100 percentsolar reliant even in seve northernclimates. However, most g enhouseshave just enough thermal storage to sur-vive one or perhaps two cloudy winterdays without back-up heit. The follow-ing chart (Figure 3.1) provides a usefulrule of thumb for determining thevolume of thermal storage required.
aWhat is the best back-upbeating system?
A Electric. space heaters areprobably the most common
source of back-up heat for solargreenhouseb They are inexpensive topurchase a.o convenient to operate.But, if th..:y are used extensively theycan be exoensive, because electricity isthe highes priced fuel in most places.When shopping for an electric spaceheater, be sure to buy one with a fanso that the heat can be movedthroughout the greenhouse.
Several grantees used wood stovesfor back-up heat. They can performwell in a greenhouse, but there areseveral poniza to consider. First, agood, energy. -Alictnt wood stove isexpensive. Cheaper, "sheet metal"stoves are not very durable, nor will
The quantities are expressed in termsof gallons of water or cubic feet ofmasonry per square 1 Ot of glazingarea, since the pun, is the mainarea of heat loss. and of course. heatgain.
"Seaton Extension" means that thegreenhouse la not used for growingduring the coldest winter months.
"Cold" climate moans that winters are*nor than the summers. "temperate'means equal summer and winter."warm means that freezing onlyOCCUrs during two or three months
Masonry is assumed le be of moderateto high density, such as stone.concrete or heavy bricks, miaow,/ isalso assumed to be eight Inches orless in thickness:
Chart assumes at least half thestorage is exposed to direct sunloghtfor at Nett half the day.
Chart assumes that the greenhouse isinsulated (as suggested in this manual)tightly built, and double glazed, exceptin warm climates
ROrbdubed from **Lo*COst AMA" sou Greenhouse." by Ron Alward and An Snapin). 0 WO by the Nntional Center torAppropriate reennobriy.
they burn all night. The length of burnfor a woodstove is critical because thecoldest time of the day is usually justbefore dawna terrible time to get upand build or stoke a fire. Wood is alsobecoming more expensive, in someplaces, as expensive per British ther-mal unit as other conventional fuels.
Woodstoves are also more difficult toregulate than other heat sources. Awood stove can't be set to come onwhen the air temperature in thegreenhouse drops to 40 °F or so. Thus,wood stoves often provide either toomuch or not enough back-up heat.Finally, a woodstove and stove pipeshould be kept at least 3 feet away fromall plants. This distance can be reduc-ed by one half if the stove and pipe areshielded from the plants with some sortof non-flammable material such as sheetmetal, bricks, or aluminum foil.
Combustion-type space heaters thatburn natural gas, propane, fuel oil, orkerosene are commonly used to heatcommercial greenhouses. They are lesscommon in solar greenhouses. Theseheaters are usually cheaper to operatethan electric heaters and since they canbe controlled with a thermostat, theyare more convenient and easier tooperate than wood. All fuel-burningheaters must be vented to the outdoors.Combustion pollutants can harm plantsas well as people. Also, compliancewith ilre codes and safety precautionsis critical when using combustionappliances in greenhouses.
QNow much back-up beatwill a greenhouse need?
AIt depends primarily on thelocal climate and the amount
of thermal storage in the greenhouse.Climatic factors include both these verity and length of the winter, thedegree of cloudiness, and the prevail-ing wind speed and direction. Ofc:.urse, these factors vary witreachsite, but for sizing back-up heat, it isprobably adequate to divide theUnited sutes into warm, temperate,and cc id climate zones. Assuming thegreenhouse has enough thermalstorage, the following chart (Figure3.2) indicates the amount of back-upheat required. The chart gives Vileminimum number of watts of electricheat needed per square foot ofgreenhouse glazing. (A note tells howto use this chart to determine the de-mand for other Wilds of fuel.)
QCan natural .entilation beused to control greenhousetemperatures?
Inadequate ventilation is one ofmost common ,treenhouse
problems. Greenhou,es can be venti-
Wed either mechanically or passively(naturally). The key is to ventilateenough.
Many greenhouse designers prefernatural ventilation, but, as manygrantees discovered, sizing errors aremuch more common with this ap-proach. As a rule of thumb, the totalvent area for a natural ventilationsystem should be about 1/6 of the floorarea with the upper vents 20 to 30 per-cent larger than the lower ones, Naturalventilation systems commonly usedoors, operable windows, and ventopenings. The rate of air flow throughthese openings varies, and the total ventarea has to be large enough to movesome air, even on hot, windless days.In naturally windy areas, vents install-ed on the windward and leeward sidesof the greenhouse can provide naturalcross ventilation.
If winds are variable and likely to becalm during many summer days, naturalventilation will have to be inducedusing the stack effect. The stack effectrelies on the natural buoyancy of warmair. Vents are installed in the east andwest ends of the greenhcuse and alsonear the peak of the greenhouse roof(Figure 3.3). (If the greenhouse is morethan twice as long as it is wide, somelower vents should also be installedalong the south wall.) As the air insidethe greenhouse is warmed, it rises andmoves out the upper vents while out-side air is drawn in the lower vents.
Automatic vent opening devicesshould be used in any natural ventila-tion system. They are in place and
Figure 3.3 There are numerousgreenhouse natural ventilationschemes.
FREE-STANDING
FOR SEASON ECTIND4004 FOR YEARODHO GROWING
COLD CLIMATE lOW 12W
TEMPERATE 8W 10W
WARM CLIMATE eW 6W
ATTACHED
COLD CLIMATE 'SW 10W
TEMPERATE 6W 8W
WARM CLIMATE 5W 5W
EXAMPLE A A otlost=coosnclenAre worm 200 so It 01 EXAMPLE B M attached iatunwarssew e404103 63 A 01
1) Fog meson mansion - 200 x 10W 1) Fa teaaon erWeloi - 100 X Sei 4. WOW20011W Mater mew
2)2
ar.rourterK1 omen; - 200 X 12W - 2) 2., rie-rozss rowing - 103 x 1W -
To um Ova Owl 10 UN 1uP beckup ne1010 you WO 10 convert watts WI10 per hour (WWI) Thy ie tip , niu11104yIngwoos Dv 14 So. N an attached greenhouse rewired 2.000 wade of electric back-up ceweity. you ovule reed a cornuuetion-typespace hooter wed la orchids 45.103 Ohre per now Thlt calculation oleo Wel to be adluoted roe the ofticioncy Of the penicillincorntoledw Orrlort berg used To do Me divide the roortaor $41 obtained by the etticlency ot the heating device True can 'moo fromrealer than (10%)1a wane rad* h Wow* Mews to lem than 3 (30%) tor Kee wood nom For many*. N you anPlaiwury2 ro We a prow* Meter with an veiciencry 04 7 (70%) lot bock-up heat end Km require 2.000 uutti of beck-up weenyaccording io the Wen. you would need a Mater end to welds 2.000 a 3 4 *AIM by 7 or 0.714 awl per Wu,
Aoprodixut kw -Low Cost PIMA'S Soho Onsenheums" 0 Aon Alvan, and An* gook: 8. Cleg0 by The Nenonel Centel lOfAncvortne Technology
Figure 3.2 Greenhouse back -up beating requirements.
8EST COPY AVAILABLE 20 22
working every day; greenhouse oper-ators are not All vents should bedesigned so that they seal well to keepout unwanted air in the winter. In-sulated coven for vents help reduce un-wanted heat loss.
Several grantees used removable glaz-ing to ventilate greenhouses in warmclimates in the summer. Thegreenhouse is designed so that the glaz-ing can be removed as summer ap-proaches, and the greenhouse thenoperates as an outdoor garden. Theglazing is reinstalled in the fall, and thegreenhouse operates in its traditionalfashion during the winter. For a systemlike this, be sure to use a lightweight.unbreakable gluing material and makesure the system seals well to preventcold air and moisture leaks in thewinter.
QIs mechanical ventilationmore effective than naturalventilation techniques?
A Mechanical or forced ventila-tion is often more consistent
and reliable than passive methods,rt!chanical systems usually do notdraw much current, and they can be fit-ted with thermostats to operate auto-matically. In Oregon, a grantee foundthat passive ventilation was not ade-quate for good plant growth, and asmall fan was added.
A wall-mounted exhaust fan com-bined with a vent opening on the op-posite side of the greenhouse is usuallyall that is required. Vent opening andexhaust fan covers can be insulated tominimize winter heat loss.
Ventilation rates of about 20 to 30 airchanges per hour are often 'recom-mended for commercial greenhouses.For energy-conserving solar green-houses, only one-fourth to one-half ofthis amount is usually necessary. Onecommon rule of thumb is that for every1,000 cubic feet of greenhouse volume,roughly 200 cubic feet per minute offan capacity should be installed.
QCan greenhouses be shadedto control temp- atures?
AYes, shading can be effective,and there are a number of
shading options. One technique is touse deciduous trees for shade. Whenthe leaves drop in the fall, most of theshading Is removed and the sun shinesinto the greenhouse. However, beforeyou rely on this approach, make surethat the leaves really drop in the fall.One grantee found that the leaves on hisoak tree turned brown in the fall, butmost of the leaves didn't drop untilthe spring. The greenhouse remainedpartially shaded all winter.
.6
QUESTIONS AND ANSWERS
Ventilation fans can be fitted with insulated covers to reduce winter-time beat loss.
Climbing or fast-growing vegetationcan also be used to shade thegreenhouse. Climbing vines such assweet peas can be trained to climb thesouth-facing glazing of thegreenhouse. In warm and temperateclimates, sunflowers grow fast enoughand tall enough to provide significantsummer shading for a greenhouse.
Another approach is to use rolldown exterior shades made of slattedwood, bamboo, aluminum, or wovencloth which are installed near the topof the glazing. They are almost alwaysmanually controlled, so thegreenhouse operator has to see thatthe shades are in the proper position.Shading cloths (a greenhouse specialtyitem) can be used for interior shading.These devices diffuse solar radiation,are relatively inexpensive, and can beleft hanging all summer.
Shading paints are also available.They can be painted on the outside ofthe glazing in any thickness to providethe desired amount of shading. Raingradually washes the paint off, so inmost climates the glazing will be near-ly clear again by fall. Residues on theglazi ag can be washed off with soapand water. Make sure that the shadingpaint is not toxic to plants whichborder the greenhouse. Also makesure that the paint is not harmful tothe glazing material. For example,
21 23
whitewash, a lime-based material, candegrade fiber-glass and plexiglass.
QHow can humidity be con-trolled in a horticulturalgreenhouse?
A Summer greenhouses are oftentoo dry, particularly in the
Great Plains, Rocky Mounta;ns, andSouthwest. In these areas, the in-creased ventilation necessary for cool-ing can also dry out the greehouse.The traditional morning watering mayhave to be supplemented on some hot,dry days, and particular care must betaken to water regularly.
Conversely, in the wintertime,greenhouse relative humidity levels aretypically too high. Condensingmoisture, caused when warm humid airflows across a cooler surface such asglass, can drip unwanted moisture ontoplants. Water drops on the gluing alsoreduce the amount of solar radiationthat can enter a greenhouse. In addi-tion, water dripping onto sills and otherwooden greenhouse structuralmembers can cause rotting.
There are a number of techniquesavailable to reduce high greenhousehumidity levels. One is to limit water-ing. The more water that is available toevaporate, the higher the relativehumidity will be. Here are several rules
QUESTIONS AND ANSWERS
for watering developed by a grantee inMassachusetts:
water as infrequently as soil andclimatic conditions permit;reducer:he quantity and frequen-cy of watering in the winter;reduce or eliminate watering ondull or overcast days;water early in the day before.thesun is high.
Ventilation also helps to reducegreenhouse humidity levels. Outside airalmost always has less moisture than theair inside a greenhouse. Thus, winter-time ventilation may be required evenwhen interior greenhouse temperaturesare low. A fan can be controlled witha humidifrtat that turns the fin on whenthe humidity reaches a certain level. Buttake care, incoming cold air can stressOf even freeze plants.
QWhat can be done toprevent moisture fromdeteriorating the green-house?
AWhenever moisture contactswood surfaces, the potential
for degradation exists. Moisture damageis even more of a problem when rot-producing soil organisms are present.An unprotected piece of 2-inch lumbercan totally rot away in five years or less.
Pressure-treated lumber, suitable foroutdoor use, is a good choice as a struc-tural building material if it will not,some in direct contact with plants orsoil. Many wood preservatives used inpressure treating are toxic. Coppernaphthanate, which is not toxic toplants, does kill some beneficial soilbacteria when it is freshly applied.Urethane and oil-based paints that arefree of asphalt, mercury, and lead aregood coatings for wood in greenhouses.
The lice of white paint inside thegreenhouse has the additional benefitof increasing light levels, which canincrease plant productivity. Blistered,cracked, el. flaking paint should betouched up immediately to preventmuch bigger painting and repair jobslater. Cracked, broken, or brittle caulkcan be repaired at the same time. If agreenhouse was built with commonconstruction nails (not galvanized),you should also check for any rustingor deterioration, and repair andreplace nails as needed.
Planting beds can be preserved by lin-ing the sides of the beds with poly-ethylene or some other inert plasticmaterial to prevent moist soil from con-tacting the wooden beds. It's better touse wood scraps as battens when nail-ing down the plastic. Do not cover thebottom of the bed, because this will pre-vent proper drainage and could lead toroot rot.
What special precautionsare necessary when dealingwith electricity in a green-thouse?
ACommon sense is the best pre-caution. The first rule is to plan
for the electrical system as you designthe greenhouse: The electrical systemsin too many greenhouses are after-thoughts. For example, electrical serv-ice has bcen added in many instanceswhen mechanical ventilation had to beinstalled after the greenhouse was built.
The second rule is not to skimp onthe electrical system. Make sure thatthe wiring and fixtures are of goodquality and suitable for outdoor use. Itis also a good idea to install groundfault interrupters. Shorts and electricalfires in solar greenhouses have oc-cured and are dangerous.
Use your head. Don't water ther-mostats, fans, heaters, switches,junction boxes, or other parts of theelectrical system. Also, greenhouseequipment such as exhaust fans andspace heaters should be of good quali-ty and properly grounded. Follow themanufacturers' recommendations foruse of this equipment. Most manufac-turers warn against use In or nearwater.
What precautioni are neces-sary for greenhouseplumbing?
ANot providing plumbing is aserious mistake. Carrying irriga-
tion water to a greenhouse is no fun atall. One common solution for attachedgreenhouses is to use an existing out-door hose bib on the common wall orto install a new one connected to thehousehold plumbing system.
Use good components in a green-house plumbing system and have an ef-fective, accessible shut-off valve. Donot rely on ,a hose nozzle to shut offwater. Most nozzles will eventuallyleak. In northern climates, be sure toprovide freeze protection for theplumbing. Locate the plumbing in thewarmest area of the greenhouse, and besure to insulate pipes, particularly ifthey are run through any unheatedspaces. Pay particular attention to thepipes if the hour has Just beenweatherized. Plumbing in an unheatedbasement or crawlspace that has justbeen insulated from the rest of thehouse may freeze now, when it did notbefore. Again, in colder regions, be sureeither to use freeze-resistant hydrantsand drain pipes, or install heat tape inthe winter. A hard freeze in a solargreenhouse, even one designed for on-ly three-season use, is not a commonproblem, but it does happen and theresults can be disastrous.
2224
QWhat makes greenhousestructures safe?
AMost greenhouse structuralsafety precautions Kaye to be
dealt with at the design, stage. Thesestructural safety features are generally*specified by building codes. Localbuilding code officials can help to in-terpret how the codes apply to specificgreenhouse and sunspace applications.
There are a few precautions thatmerit special attention. The first isoverhead glass. Use tempered glass inany overhead situation, or better yetsubstitute fiberglass-reinforced plasticor some, other suitable plastic glazingmaterial: Also, make sure the glazing isproperly secured and supported. Manyglazing materials (especially temperedor thermal pane glass) are very heavyand need to be properly supported.
Yotralso need to make sure that yourgreenhouse or sunspace is designed toendure any local environmental condi-tions. Obviously, a greenhouse built ina rainy climate requires specialmeasures to prevent structural damagefrom rotting. Less obvious, and morecommonly overlooked, are the.effectsof wind and snow. At least two granteeshad their greenhouses destroyed byhigh winds and others had problemswith snow (Chapter One). In areaswhere either heavy snow loads or highwinds can be expected, it is critical tomake sure the greenhouse or sunspaceis properly designed. It may help tohave plans reviewed by a structuralengineer.
lirminenGREENHOLIIE MANAGEMENT, MAINTENANCE, AND SAFETY meminimar
These DOS projects provide information . on greenhouse operation andmanagement.
KuskolrOtitit sour greenhouse . : / DOS 14100 XLoWell Lambert s.: .. *. . DOS Grant No. DE-PG51-79R000061Aniaki AK - : ° .. . ATMIS 112; AK19411
A 900sq., ft. *Aar greenhonse was constructed in Malt, AL An internal rrigerwtIs raised at night to insulate the south Water if In forty 55salion drums
= on the north wall.-A wOod stoveprovides ,7up beat extended cloudy or coldmriodi.. The ,greenhottie extends the local awowlnst season from March throughNovember, Little .or no COO or Oeff0fMASICC data is VMS. 411.11.bliCif filliti report.
SOW greenhouse. for Sunflower DOB legion 1Y .. . .
public Mealy . .: . Y. : , DOS Grant No DI4044-81K410494Anice C. Powell ;- -. .. . .-- ,:-,-- - ATMIS 1D:. M581-009" -
India**, MS .
A solar house (65 sq. ft.) Was retrofitted on a small librarYin SiXtflower, MS.The functions as in airlock entryway and therinsil storage is incorporated -
in the greenhouse to help supply space heat to the library in the winter. The east andwest was are removed in the.s.iminer for
.
ventiltion purptaies.lmited or no perfor-=ICC dui .s presented.
.
,
Uipzdhjtechnical systems of the : DOS Regio IV
erna6ve homestead .---, : - - DOS Grant No..0114044-8011410312MJ. Derry. White . , , -..- ,... -.. ,. . ., . .,ATM155111. KY-00-011 .
Louisville, KY :The iniplettiented technical mOdiftMtions disavowed as thi end of their 1979
project. Several aspects of the greenhOOse need-ed upgrading because of poor delign and outistraCtiort oh* ,-.. skilled labor.Specs y, alba* screen wal. installed Mita& thogreenhoule 'Witmer Coolingand ductwork wai hishdled tO More OEMs heat ftvm the orcenbottie M.the living apace.This grant provided for remetlykd these technical shortcomings. Costa-of materialsare presented. No data archaises in performance *reported. Monitoring is planned.
Notrzalrem cooperative solar DOS Region 1. DOS Grant No. DE1,041149R110042
saliso"ralapper ATMIS IDs MA79-015Orange, MA
A 2800-sq. ft. passive solar community COMOICteigi lifeeOh0111e was constructed !iMA Wing volunteer labor and workshops. The final report describes these construction sequence and provides operation and mlnagememauSfier
dons. About $1000 worth of vegetablei and other plants were sold the first year. Thermalperformance monitoring of the greenhouse was conducted and a biologies! pest con-trol program was initiates.
2523
CHAPTER FOUR
THE LIVING GREENHOUSEA GUIDE To
GROWING PLANTSMany solar greenhouses have been built primarily for hor-
ticultural purposes, particularly food production. But hor-ticultural production, perhaps more than any other use, hasbeen disappointing for owners and operators. The reasonsfor poor results vary, but a review of the grants indicatesseveral common problems, including designs which don'ttake into account the biological and environmental needsof plants; a poor understanding of the basic principles of,greenhouse hor!culture by the grower/operator; and a lackof understanding of the additional time and resources re-quired to operate the greenhouse.
Growing crops in a greenhouse can be challenging for eventhe most experienced gardener. Although the basic re-quirements of seeding, watering, cultivating, and harvestingare the same, the greenhouse environment is totally differentfrom the garden. A greenhouse is enclosed and more con-trollable than a garden. It is also a much more intensive en-vironment than the garden. Plants tend to grow more rapidly,but so do pests and diseases. The grower/operator must striveconstantly to maintain control of this highly interrelated en-vironment. In order to maximize production within a limitedspace, a greenhouse must provide the best possible condi-tions for plant growth. Thus, a basic understanding of themost critical biological processes and an awareness of theeffects of changing environmental conditions on plantgrowth are essential.
Nor plants to grow, light, proper temperatures, water, car-bon dioxide, and nutrients must be present at the right timesand available in the correct amounts. If any one of these isabsent or is in shor supply, plant growth will be slowed orstop completely. Ile missing or lacking condition is com-monly referred to as the "limiting factor." A review of thebasic biological processes of plants will help to better under-stand how limiting factors affect plant growth.
The following questions and answers address how thegreenhouse growing environment with its interrelated conditions can be managed to maintain and improve plantproductivity.
24 26
Qlime can light levels to a solar gswenbouse beincreased?
AMuch of the interior of the greenhouse may beshaded at certain times of day if east and west walls
are not glazed. The length of the greenhouse determines howmuch strzding -;.-1:1 occur in the late afternoon and earlymornings if the east and west walls are unglazed. Since manysolar gremhouses have solid roofs, the interior may be shad-ed even more in the late spring, summer, and early fall whenthe sun is high in the sky. The steeper the glazing and deeperthe greenhouse, the more potential for shading exists.
Because of shading problems, many grantees diicoveredthat their solar greenhouses often had insufficient lightlevels for optimum growing conditions. Light is the sourceof energy in photosynthesis,. and without light, growthstops (see Sidebar: The Basic Processes for Plant Life andGrowth). For instance, in warmer months, plants towardthe back of the greenhouse often are stressed due to poorlight levels. They become phototropic as they lean towardthe south glazing for light. This causes elongated, spindly,sometimes yellowish growth with decreased productivity.Squash plants have been known to break off at ground leveldue to the combination of heavy fruit and the stretching forlight.
The best time to deal with light levels is during designand construction (Chapters One and Two). Be sure tocalculate when and where shaded areas will occur withinthe greenhouse based on the depth, length, and orientationof the structure, the angle of the glazing, and the angle ofthe sun at different times of the year. (Books cited inChapter Six provide information on how to do thesecalculations.) PAy particular attention to late spring, sum-mer, and early fall conditions. If growing areas will beshaded at any time consider the following:
Add glazing overhead. This is most helpful for summerconditions, especially in deeper greenhouses with steepglazing angles. Overhead glazing allows direct lunlight topenetrate farther into the interior. Insulating panels shouldbe used to cover this glazing during late fall, winter, andearly spring.
Add glazing on the cast and/or west walls. This willreduce early morning and late afternoon shadows. If onlyone end wall is glazed, it is generally better to glaze the east-end which allows the greenhouse to warm up quickly inthe mornings. The shorter the greenhouse is, the more theeast and west walls will shade the interior. If a greenhouseis less than 12 feet long, both end walls probably should beglazed.
The type of glazing material will affect the amount oflight within the greenhouse. Some glazing materials such asfiber-reinforced plastics diffuse (scatter) the light betterthan other glazings. Thig helps to brighten otherwise shad-ed areas, and most plants do well in a strong diffuse light.
To diffuse light even more, paint all interior wallswhite (Be sure to use lead-free paint.) In the summermonths, hanging a white curtain or other reflectivematerial over the dark thermal mass in the greenhouse willalso increase diffuse light levels.
Plan your growing areas to minimize shading. Bedsand benches should be placed where they will receive themost light. In a greenhouse with a kneewall, the beds orbenches should be at least as high as the kneewall to pre -tent shading this prime growing area. As a grantee in Mainereports, place crops so that taller and vining plants aretoward the back or east and west sides of the greenhouseso they won't shade other plants.
25
QUESTIONS AND ANSWERS
Overbead slasins We Si, additional light when thesus is high in the sky in the summer.
-s.
t.61-74
A white curtain or blind installed in t of darkcolored thermal mass can re light back on thegrowing beds.
27
QUESTIONS AND ANSWERS
Q. Is supplemental lighting effective?
AYes. Many vegetables need a minimum of eighthours of daylight to grow and produce properly. In
many northern climates this amount of sunlight is simplynot available in the winter and supplemental lighting can beused to increase plant productivity. Lights can be used tostart warm weather seedlings very early (January). Accor-ding to a grantee in Massachusetts, fluorescent lampsthestandard white metal light fixtures with 48-inch "coolwhite" or "warm white" fluorescent tubescan be used asgrow lights. Both "cool" and "warm" fluorescent tubesare often used in the same fixture. These lights are typically80-watt systems and cost between $20 and $60 per fixture.For growing seedlings, these lights should be installedwithin 3 to 5 inches of the tops of the seedlings. They needto be operated for only a few hours per day on overcastwinter or early spring days. The result will be healthier,stockier plants.
Q How can the growing area of a greenhouse beused most effectively?
AOne of the major goals of greenhouse designersand growers has been to get better use out of the
space inside a greenhouse. Some experts suggest that about70 percent of the floorspace of a greenhouse can be usedas growing area. But the experience of grantees has shownthat only 50 percent or less of the total floor area commonlyis used for plant production. This is fine if the principal pur-pose of the greenhouse is for heat production, living spaceor recreation, but a much more effective use of space is re-quired if the primary purpose is "norticultural production.
There are a number of ways to use space more effective-ly. First, consider thermal storage containers. The common55-gallon drum takes up a lot of space, but can be used tosupport growing containers or benches (Figure 4.1). Raisedbeds are another good way to use space effectively, becausethe area under the bed platforms can be used to store sup-plies or for thermal storage units. The walkways betweenthe beds can also be narrower. Raised beds are also mucheasier and more convenient to work with than growing atground level. Large pots, buckets and soil-filled drums canbe tucked away In otherwise unused locations to provideadditional growing space.
As a rule of thumb, the deeper the bed (up to about 2 feet),the better the plant growth. Raised beds, as with all grow-ing containers, should also contain a few inches of sand and
26
Figure 4.1 Fifty-five-gallon drums can be used tosupport planting beds and trays.
Figure 4.2 Trough growing beds are a good ideawhen planting at ground level.
gravel in the bottom to aid in drainage. Drilling 3/4-inch holesin the bottom of the beds or building slotted bottoms areother common drainage techniques.
Inadequate drainage leads to root rot and poor produc-tivity. If a ground level growing bed is the only thing possi-ble, you still need to provide adequate soil drainage. An in-sulated trough-type growing bed will function well in thesecircumstances (Figure 4.2). Also, with a ground level bed youshould consider digging out the walkway or installing akneeling platform to make access to the beds morecomfortable.
Finally, greenhouses have quite a bit of vertical space,much of which often goes unused. Always remember poten-tial shading effects, but be imaginative and let things hangor climb. Tomatoes and cucumbers in particular can be train-ed to climb to the ceiling rather than sprawl all over thegrowing bed and around other plants.
Think about ways to get tools up and out of the way. Manygreenhouses have "air-lock entries" or vestibules incor-porated in their designs to conserve energy. These are idealareas to store tools and supplies. Keeping tools and suppliesup and out of the way will reduce clutter and hazards, Theyare also great potting rooms during most of the year.
28
QWhat are the seasonal differences to greenhousegrowing practices?
Summer in the greenhouse Is characterized bylong, hot days with lots of bright light (assuming the
greenhouse is properly designed). In colder climates andhigher elevations, the greenhouse can produce heat- andtight-loving plants without damage from frost or hail. Inwarmer climates where outdoor gardens are in full swing,this may be the ideal time to clean and sterilize thegreenhouse by allowing it to heat up to high temperatureswhile it is empty. A grantee in North Carolina successfullyused this process, sealing the greenhouse for 4 to 7 days inthe peak of the summer. Temperatures rose to between120 °F and 140 °F and killed most disease-causing spores andinsects.
Fall is a transition season. Summer crops can still producewell late into the fall. Several crops do well in the fallgreenhouse and can be used as filler crops if transplants areready to go in when summer crops such as tomatoes andcucumbers are pulled out. These fall vegetables include broc-coli, cauliflower, chinese greens, lettuces, and chard.Spinach, beets and radishes are also suitable and should beseeded directly.
Late fall is the time to establish winter crops if thegreenhouse will be used year round. The timing depends onthe particular climate and greenhouse and is best determin-ed by experience. Grantees in Maine and Michigan discoveredthat getting winter vegetables close to maturity before thecoldest weather sets in is the key to winter greenhouseproductioni,
Plant groVith is often very slow in the winter due to thelow temperatures and low light levels. Freezing temperaturesinside northern greenhouses are not uncommon if back-upheat is not used. Without supplemental light and heat, thechoice of crops is usually reduced to the most hardyvegetables: the leafy greens such as chard, kale, parsley,chinese greens, leaf lettuce, endive, mustard greens, and beetgreens. Green onions, brussel sprouts, collards, and chicoryare also suitable winter crops. Occasionally, crops such ascarrots and peas are seeded in the fall and held over for springproduction.
The spring greenhouse season Is characterized by increas-ing light levels. Early spring can still be cold, but more lightmeans increased production. As temperatures begin to warmup, vegetables such as squash, carrots, peas, and beans canbe started. Seedlings for the outdoor garden and the sum-mer greenhouse are usually given a high priority in the springgreenhouse.
Q What plant varieties are best in greenhouses?
ABecause of light limitations and widely fluctu-ating temperatures, not all plants do well in the solar
greenhouse. In addition, of the crops that do tolerate theseconditions, some varieties produce better than others in dif-ferent areas. Figure 4.3 shows the recommendations of agrantee in Massachusetts. (For NCAT's greenhouse growingexperience in Butte, Montana, see Thermal Perform-ance. . . cited in Chapter Six.)
QDoes greenhouse growing require any specialsoil mixture?
AGenerally, yes. While the subject of greenhousesoil mixtures is very complex and different crops
may require different soil compositions, one very importantcharacteristic stands out. Greenhouse soils should be lightand well aerated. One popular soil mix that drains well yet
QUESTIONS AND ANSWERS
Lefton
NI il BMW, CftwOOSseitlIn
Leal Salad Bowl Heat and cold tolerant.doesn't become bitter
Leal Grand Rapids Forcing Esc* tient for winter andeery vamp
Leaf Grand Rapids Tip Bum Tolerant. veryheat tohlrent
Lae Wsksnana Dam Wean Larger Naves. Minngreen
Buttonwood Rsinc-doKilicas Wiry Mow to Oak goodtwat tolerance
Figure 4.3 Recommended greenhouse vegetablevarieties for Massachusetts. Source: Klein, Miriamand Ron Alward, Community Greenhouse Work-book, Module III, Commonwealth of Massachusetts,Executive Office Communities and Development.
retains adequate moisture is two parts of good garden soil(black dirt), one part sand or perlite, and one part organicmatter such as peat moss, compost, or well-rotted manure.
Earthworms also help aerate the soil. They multiply rapidlyand will greatly improve the quality of greenhouse soil. Trybringing in earthworms from outdoors or buy your own cropin bulk from a fishing bait dealer.
QIs fertilisation important for greenhousegrowing?
AA well-regulated fertilization program is criticalbecause greenhouse plant production is both con-
tinuous and intense. There are two basic ways to supplynutrients to plants in the greenhouse. The first method isto use commercially available inorganic chemical fertilizers.Inorganic fertilizers are available in precisely calculatedstrengths and are labeled according to their nitrogen (N),phosphorus(P), and potassium (K) contents. For example, a10-10-10 fertilizer is 10 percent nitrogen, 10 percentphosphorus, and 10 percent potassium. These fertilizers areeasy to use and are readily available at hardware stores,garden shops, nurseries, and greenhouse supply companies.Instructions for use are usually included on the fertilizercontainer.
The other approach is to maintain soil fertility with organicamendments. The key to this approach is maintenance. Manynovice greenhouse organic gardeners tend to overlook theneed to constantly test and amend their soils. Soil shouldbe tested for the major nutrients (nitrogen, phosphorus, andpotassium) and pH (the measure of the soil acidity) at leastevery six months and replenished as needed. Nitrogen,phosphorus, and potassium are the nutrients that are con-sumed in the largest quantities by plants and therefore arequickly depleted during intensive production. Maintainingproper pH levels (most vegetables prefer a range of 5.5 to7.0) is also important because extreme aridity or alkalinitywill affect the availability of nutrients to the plants.
27 29
QUESTIONS ANI) ANSWERS
The best (and cheapest) organic amendment is thoroughlydecomposed -compost. Well-rotted manures are also good.But as a grantee in Michigan noted, make sure the manurereally is well rotted. Fresh manure will heat up in the soilas it decomposes and actually deplete the soil of nitrogen.Two to three inches of both compost and well-rotted manurecan be added to the soil beds between plantings. Other formsof organic soil amendments include blood meal, bone meal,_rock phosphate, fish emulsion, liquid seaweed, and woodash. As noted on the package, each of these has particularstrengths as far as N,P, and K are concerned. These organicamendments are often available where inorganic fertilizersare sold.
QAre hydroponics a good choice for the beginninggreenhouse gardener?
Probably not, because there is a certain "art" tohydroponic gardening. Hydroponics is the techni-
que of growing plants in a ,soilless medium such as sand,gravel, or perlite. These inorganic substances act only as rootsupports for the plants. Nutrients, either organic or commer-cially prepared inorganic mixtures, are supplied to the plantsby a system of irrigation usually run by pumps with timingdevices. Most grantees who experimented with hydroponicswere unsuccessful. However, hydroponic production can befun if you like to play with gadgetry or enjoy a more high-tech approach to food production.
Successful hydroponic food production does have severaladvantages over soil culture.
With a sterile growing medium there will be no prob-lems with soil-borne diseases and no soil to amend.
No weeding, watering, or cultivation is necessary.
t LI IL. 1
-2--..6111orr. -__
Many grantees otters hydroponic gardening. InIbis experimental system nutrients are circulatedtbrougb perforated tubes located 8 inches below thesurface of the travel bed.
28
The use of commercially prepared fertilizer mixes en-sures that nutrient requirements are met as long as directionsare followed carefully.
Automation saves time and labor once the system is setup.
However, there are additional costs of pumps, timers,piping, and tubing, and mixing containers, as well as the costsof maintaining the equipment that also have to be consideredbefore you decide to install a hydroponic gardening system.Grantees found that hydroponic systems can be expensive.
QHow can greenhouse pests and diseases be pre-vented?
AThey can't. Sooner or later pests and/or diseaseswill appear, even in the best managed greenhouse.
The combination of three conditions leads to problems: thepresence of a pest or pathogen, the proper environment, anda susceptible plant. Prevention of these conditions is alwaysthe best way to avoid problems, but it is notalways easy toachieve.
The best way to deal with pest and disease problems isto be prepared with information and control techniques.Spend some time before problems arise learning about themost prevalent greenhouse diseases and how to recognizethe most common greenhouse pests. Then find out whatkinds of control techniques are available. Most important-1y, spend time observingreally lookingat what is hap-pening in the greenhouse. Don't disregard anything orassume that you know what is going on. Look at every brownspot, every wilted leaf and blemish. Look in all the corners,nooks, and crannies of the greenhouse for possible pestpopulations. When you suspect a problem, try to identifyit. Seek help from books, experienced growers, or your localextension agent or agriculture school experts. Then deter-mine what control technique(s) can be used.
The most common greenhouse pests are aphids, whitefiles,spider mites, mealybugs, scale, caterpillar-type worms, snails,and slugs. Controls for these invaders can vary from the mostdirect physical methods (handpicking and smashing), tospraying with chemicals or using biological control tech-niques. Biological controls include the use of insectpredators and parasites as well as b-..cterial and fungousagents.
To use biological control techniques effectively, it is im-portant to understand the environmental conditionsnecessary to establish and maintain a population ofbeneficialinsects. Generally, high temperatures (over 90 °) aredetrimental to most insects, and all beneficial insects needa pesticide-free environment. Most insectories which sup-ply beneficial insects will send along information about theirhandling, the conditions they need to thrive, and how tointroduce them into the environment. (Be sure to requestthis information if it is not made available to you.) Ladybugs,for example, should be released in a greenhouse in the eve-nings or on cloudy days to allow them some time to getsettled in their new home. If they are released on brightdays, ladybugs will fly to the glazing and usually die as aresult; this happened to a grantee in Michigan.
Solar greenhouses and sunspaces,perhaps more than any other type ofappropriate technology, have beenwidely disseminated through com-munity workshop education. Some ex-amples would be a group of localcitizens gathering for a weekend, "barn-raising" of a greenhouse on the side ofthe town hall; food co-op membersadding some growing space to a com-munity store; or a group of city workersinstalling a sunspace on an elderly.couple's home.
Construction workshops sponsoredby DOE grantees have produced morethan 100 greenhouses and sunspaces at-tached to a variety of buildings undervarious conditions: homes, community .energy centers, public schools, univer-sity experimental farm units, environ-mental education centers, correctionfacilities, and several other local andstate government buildings. These, andthousands more, have been built withan emphasis on community educationand they demonstrate that solar
greenhouse/sunspace technology can beeffectively transferred throughworkshops. However, this transferprocess does not always occursmoothly.
Collectively, the grantees learned agreat deal about educating adults inhands-on, community constructionworkshops. The goal is to teach work-shop participants enough about design,materials selection, and constructiontechniques so they can build their owngreenhouses and then teach others theirnew skills. This strategy employs whatis known as the multiplier effect, andit is intended to promote the construc-tion of other greenhouses as a result ofthe community workshop. For exam-ple, one California project resulted inan average of twelve greenhouses beingbuilt for each of six workshops held.
Grantees from Vermont, Arkansas,Kansas, Washington, and Californiadocumented (based on limited monitor-ing periods) that from two to six addi-tional greenhouses were constructed in
the community Lir each greenhousebuilt in a workshop. A grantee fromConnecticut reported that the publicitysurrounding the success of his green-house project led to the funding ofseveral additional greenhouses in thearea.
Not all workshops have been un-qualified successes, and some havefailed. Many of the problems that havebeen mentioned previously in thispublication, have affected greenhousesand sunspaces built under communityor workshop conditions. In addition,certain problems associated with doing..anything with groups of people haveaffected project successes.
The information that follows ad-dresses several of the more importantconsiderations when planning and con-ducting solar greenhouse/sunspace con-struction workshops. The lessonslearned can be instrumental in futuresuccesses.
S .Tht
3741''.4 ,
.1
4,
The effectiveness of worlesbops is multiplied when participants return borne to build tb. fir own greenhousesor sunspaces.
30 32
Qel How should communitygreenbouse /sunspaceworksbops be publicized?
AThe greater the turnout for acommunity workshop the
greater the likelihood that active par-ticipants will go on to build a largenumber of greenhouses or sunspaces.Publicity can be critical. Sponsors canuse formal media such as television,radio, and newspapers, or informalmedia such as flyers, posters, newslet-ters, and word of mouth. The ap-propriate balance of publicity methodswill differ from place to place based onthe purpose and = audience of theworkshop and the characteristics of thecommunity. It is always helpful to studythe publicity efforts for other similarevents in the local community.
A California grantee analyzed theeffectiveness of his publicity efforts. Heasked participants where they foundout about the workshops, and theresults are interesting: 47 percent readabout them in the newspaper, 23 per-cent heard about them from friends, 13percent from the flyer/poster, 6 percentfrom television, and 10 percent fromother source-" The point is to use avariety of publicity means.
Also, timing is important in allpublicity efforts. The day after a tele-vision story about the California proj-ect, over 50 people attended one of theworkshops. However, attendance wasdown the next week, and stayed downuntil local newspapers began printingstories about the project. The granteealso collaborated with the producer ofa community-owned television stationto develop a videotape show about theproject, which could be used topublicize subsequent workshops.
Both formal and informal media areexcellent ways to publicize a workshop,and it always helps to know somebody.Another grantee in California reportedthat personal contact with a mediarepresentative well in advance of con-struction workshops proved invaluable.The media representative becamefamiliar with the project and supportedit with his coverage.
QIL bat are the mostimportant considerationswhen designing communityeducation programs?
APeople may know how muchtime and effort it takes to
prepare successful educational activitiesfor children. These same people oftendon't realize that planning effectivecommunity education programs foradults often requires even more effort.Adults tend to have clearer expectationsthan children, and it is vital that the
workshops be carefully designed andimplemented with the specific audiencein Rtind.
In Georgia, a grantee who developeda community education program forlow-income adults found that under-strnding the education and achieve-ment levels of the audience was essen-tial when selecting or developingsuitable educational materials to be usedin ,the workshop. The grantee foundthat most of the available materialswere written for literate, well-educatedreaders, and were hard tA -adapt for in-dividuals with limited education. Likethe Georgia workshop participants,those who could benefit most from theuse of solar greenhouses and sunspacesare thOse without the reading skills tounderstand most of the materialspresently available.
Another important element in design-ing a community workshop is evalua-tion. The California grantee whostudied publicity efforts also used ex-tensive evaluation after the workshopto find out how much the participantshad learned and what recommenda-tions they had for improving the pro-gram. Because of the evaluationresponse, subsequent workshops weremodified and improved.
Several other grantees recommendedthat a brief evening program shouldprecede the hands-on constructionworkshops. At the evening sessions,participants learned about solar theoryand design, and materials. While theseimportant topics were touched on dur-ing construction, grantees felt that theevening sessions provided a needed op-portunity to ask questions and reallylearn the necessary background infor-mation. The evening session also leftmore time to concentrate on construc-tion skills during the hands-onworkshop session.
Now long dr qs it take tocomplete a greenhouse orsunspace in a communityworkshop?
AA primary goal of most com-munity workshops is to teach
skills through hands-on experience.That goal is not exactly consistent withan efficient construction job. It is acommon myth that a greenhouse can bebuilt in one weekend by a group oflargely non-skilled people. No matterhow many skilled people participate orhow well the event is organized, green-houses simply cannot be completelybuilt in a weekend.
The most successful projects con-structed simple structures that requiredminimal construction skills. Othergrantees built more substantial struc-tures that required more time and
31 33
QUESTIONS AND ANSWERS
It is vital that worissbops becarefully desisned and Imple-mented with the specific audiencein mind.
sophisticated skills. But in both cases,construction took considerably longerthan anticipated.
Generally, grantees reported thatgreenhouses were approximately 60 to90 percent complete at the end of atwo-day workshop. A sophisticatedgreenhouse design was built inMichigan that took 1,C00 hours to com-plete, and the workshop coordinatornow stresses the need to plan for addi-tional labor, perhaps by extending theworkshop beyond a single weekend.
It is important to understand bothhow much time will be required dur-ing the workshops and how much timewill be required to finish thegreenhouse after the workshop is over.Grantees in California and Connecticutleft final construction details to thehomeowners, and found that this ap-proach was usually unsuccessfulbecause the homeowners had othertime commitments and lacked adequateskills. In fact, in California, delays infinishing construction left a greenhousevulnerable to bad weather, and exten-sive work was required to repair thedamage. ,
How should cost estimatesfor greenhouse materials befigured?lorliAA large number of grantees
. reported cost overruns. Proj-ects in Rhode Island and Maine foundconstruction costs to be $1,000 higherthan original estimates, while anothergrantee in Maine calculated that costswere 12 percent over original projec-tions. Such overruns occur for twoprimary reasons. First, many workshopsponsors simply cannot estimate costsas well as sola contractors or otherbuilders. Connunity groups oftenunderestimate the amount of materialsneeded to complete a project or forget
1
QUESTIONS AND ANSWERS
to incorporate additional costs that fre-quently arise with retrofit projects.
Second, cost estimates are madewhen funding is applied for or whenthe greenhouse is first designed,without considering cost increases dueto inflation. By the time they wereready to build their greenhouses,grantees in Massachusetts, Kansas,Alabama, West Virginia, and Kentuckyfound that their original cost projec-
. tioni were too sow. An individual canwait until he or the can afford thenecessary materials. In a workshop set-ting, however, scheduling conflicts maymake waiting difficult or impossible,leading to cost overruns.
QWhat problems can occur ifmore than one fundingsource is used for a green-bouse/sunspace project?torisimmi
AMany groups -need funds fromtwo or more sources to con-
duct their workshops. Funds for labormight be supplied by one source,materials funds by another. Coor-dinating a project that relies on multi-ple funding sources can be difficult.Funding delays at critical times can crip-ple a project. Several grantees nowknow that careful planning and effec-tive communications with fundingsources are mandatory. It is sometimesimpossible for the project organizer toanticipate problems that arise, becausethe operations of the funding agenciesare beyond his or her control. Nonethe-less, coordinators must be aware of pit-falls. One Georgia grantee recommendsapplying only for grants .that will coverboth materials and labor.
Funding sources usually requiredetailed accounting and progressreports, and occasionally, for technicalprojects, systematic monitoring docu-mentation. These requirements cancause problems, as a New 'Hampshiregrantee found out; his proposed projectwas cut back as a consequence. Again,community organizations often do nothave the experience to comply with theexpectations of the funding source, anddo no realize there are problems untilit is too late. Grants documentation re-quirements can be even more of a prob-lem when the organization is acting onbehalf of local families who have evenless experience. The community organi-zations must become familiar with alldocumentation requirements associatedwith a grant, and make these require-ments clear to all participants as an in-tegral part of the project managementprocess.
Wbo should lead greenhouse/sunspace constructionactivities?
4 stt
4 11;4;';(1
It ie a common titytb that as grandmas, can be built in a one - weekendworksbop by largely non- skilled people.
A, Solar greenhouses or sunspacesmust be carefully constructed.
Therefore, the workshop leader mustknow traditional building constructionpractices, and be experienced withsome of the unique aspects ofgreenhouse/sunspace construction. Aleader who is unfamiliar with carpen-try, glazing, and electricity can hamperthe construction process and disillusionthe volunteers who come to contributetheir time and learn new skills. Projectorganizers must be enthusiastic abouttheir work, but enthusiasm alone is notenough.
Grantees in Massachusetts found thateffective construction supervision iscritical to the successful completion ofthe sunspace or greenhouse. Equally im-portant is the fact that the leader mustalso be a good teacher and have the ex-perience and patience needed to allowpeople to learn by doing thingsthemselves.
QWhat problems arise whenvolunteers are used to builda greenhouse or sunspace?
AWorkshop volunteers are notjust a source of free labor. They
expect to work in exchange for newknowledge and skills. By learning theseskills, volunteers become more self-reliant, better able to build their ownsunspaces or greenhouses, and betterable to assist others.
Project organizers must have realisticexpectations of volunteers. Skill levelsvary considerably among volunteers,and so does interest. In Michigan, 1,600hours of volunteer work were neededto complete a small greenhouse retrofitof approximately 200 square feet. The
32
volunteers were enthusiastic but oftenlacked even the most basic carpentryskills. In another project, a Massachu-setts grantee fou d that the construc-tion design was too sophisticated forthe average volunteer, and staffmembers had to complete the green-house when volunteer interest waned.Grantees in Louisiana and Missouri alsomentioned that the numbers of volun-teers dropped off when constructiontook too long to complete.
In California, a grantee teaching asolar course at a community collegediscovered that his students could notreceive credit for participating in con-struction workshops, because theconstruction site was in the jurisdictionof another college. Only the most in-terested students chose to continuewith the project, which drasticallyreduced the anticipated constructionlabor pool and lengthened the schedule.This same grantee discovered thatstudents were less likely to do sometasks (hand-digging trenches) thanothers (attaching the glazing). He even-tually had to hire a contractor to com-plete the trenching.
Several grantees who relied onvolunteer labor indicated that, at times,too many volunteers turned out whenthere were too few tasks while othergrantees indicated they had too fewvolunteers when many hands wereneeded. These problems have to be ad-dressed with careful management andplanning so the right number ofworkers is available at various stages inthe construction process. Such planningis essential if volunteers are to learn thebasic skills for greenhouse constructionwithout becoming frustrated orconfused.
34
ImumummumgmCONSTRUCTION WORKSHOPS
. .
.Grant No..0044441011112038.9.14404;. -r-s .2
.4;at m4004014 -commidd.-Ssitohosidaithorgehthiftoicedmft the
There are several publications, which are cited later inthis chapter, that provide good information on.many of thetopics presented in this publication. These books, papers,and articles at.. a good place to start looking for answers tomany of the questions that might come up as you design,build, or operate your sunspace or greenhouse.
State energy offices may be able to help with morespecific questions. Most of these offices have knowledge-able people who can provide advice directly or providereferences to other good sources. In some areas, gardenclubs, energy conservation groups, food co-ops, or othercommunity organizations may be helpful. A "fellowship"of greenhouse owners was organized by a grantee in Ala-bama to share their experiences and information.
In some cases, it may pay to consult a professional. Agrantee in New York, who was primarily interested inresearching and developing the design for an aquaculturaland horticultural greenhouse, found that the constructiondetails took up too much time. She suggested that a profes-sional could have taken care of these details, and she couldhave concentrated on the broader design questions.
Professional help must be selected carefully. Severalgrantees had their projects complicated by poor servicefrom contracted help. Remember that not all builders oreven architects are familiar with solar greenhouse/sunspacedesign. Even though greenhouses and sunspaces arc simplestructures in some respects, they must be thoroughly un-derstood before a good design can be developed. There arepeople who specialize in solar design who have the knowl-edge and experience to provide good service. However,don't assume that all "solar" architects or builders auto-matically provide quality work. Grantees in Maine had tofire their solar consultant halfway through the project. Aswith the selection of any professional, consider severalcontractors if possible, ask for references, and visit othergreenhouses or sunspaces that they have produced.
If you feel your construction skills are weak, 'considertaking courses (usually available at night) at a localvocational-technical school before you try to build agreenhouse or sunspace. Courses in carpentry, plumbing,and wiring, designed with the novice -adult in mind, areusually available. Your local vocational-technical schoolcan also recommend supplemental reading materials.
There are no books written specifically about greenhousesafety and maintenance. However, most problems can beaddressed through proper planning and common sense.Local building code and inspection departments willreview plans to make sure designs are safe and meet localspecifications. Information on greenhouse safety and main-tenance can also probably be obtained from your stateenergy office, the Agricultural Extension Service, or yourcounty agent.
Help in dealing with horticultural problems can comefrom many places. Books and other publications, availablefrom many sources, including public libraries, are goodsources of information. Greenhouse supply companies and
34
Sunspaces and greenhouses must be carefully con-structing.
garden shops often have knowledgeable individuals whocould answer your questions. Local commercial green-house growers and nursery operators are often willing toshare their knowledge. And your local cooperative exten-sion agent is paid to aid the public with questions and prob-lems in all areas of agriculture. Many state agricultureschools have horticulture departments which can providea wealth of information.
Acquiring your own library of bdoks and other materialsis handy for quick reference when problems or questionsarise. Here are some items that are particularly useful:
36
Four books providegood, general backgroundinformation on solar .
greenhouses and sun-spaces:
Yanda, Bill and RickFisher, The Food and HeatProducing Solar Green-house, John Muir Publica-tions, Inc., Santa Fe, NM,1980, available in manybookstores.
Greep:house Gardening,A Sunset Bobl,. Lane Pub-lishing Co., Menlo Park,CA, 1976, available :nmany bookstores.
James C. McCullagh, ed.The Solar GreenhouseBook, Rodale Press, Inc.,Emmaus, PA, 1978, avail-able in many bookstores.
Alward, Ron and AndyShapiro, Low-Cost PassiveSolar Greenhouses: A De-sign and ConstructionGuide, The National Cen-ter for Appropriate Tech-noiogy, Butte, MT, 1980.173 pp. $7.00. Availablefrom NCAT, P.O. Box3838, Butte, MT 59702.Also available in manybookstores, published byCharles Scribners andSons, New York.
Useful information ongreenhouse operation andmangement can be foundin the following books:
Wolfe, Delores, Grow-ing Food in Solar Green;houses, Dolphin Books,Doubleday & Company,Inc., Garden City, NY,1981, 192 pp. 110.95.Available in many book-stores.
The introduction to thisbook describes the green-house growing environ-ment and provides man-agement information.
Bartholwnew, Mel,Square Foot Gardening,Rodale Press, Emmaus, PA,1981, 345 pp. 19.95.Available in many book-stores. This useful bookwas written for outdoorgardening but many of theintensive gardening man-agement techniques canalso be used in green-houses.
Klein, Miriam and RonAlward, CommunityGreenhouse Workbook:Where do we go fromhere? produced by Com-monwealth of Massachu-setts, Executive Office ofCommunities and. Develop-ment. Available from: TheExecutive Office of Com-munities and Develop-ment, Attention: Ted Live,100 Cambridge Street,Room 1103, Boston, MA02220.
Module II of this threemodule series produced bya DOE Appropriate Tech-nology grantee focuses ongreenhouse design consid-erations. It also includes awealth of information onhow to manage a greeb-house once it is designed.
Clegg, Peter and DerryWatkins, The CompleteGreenhouse Book, GardenWay Publishing Co., Char-lotte, VT, 1978. 280 pp.$8.95. Available in manybookstores. Interspersedthroughout this book isuseful information on themanagement of solargreenhouses. The interiorgreenhouse environment iscarefully described andtechniques for managingthat environment are pro-vided.
For more information ongreenhouse horticulture:
Smith, Shane, The Boun-tiful Solar Greenhouse,John Muir Publications,Inc., Santa Fe, NM, 1982.This is probably the bestoverall boolcon solargreenhouse horticulturecurrently available. It pro-vides both the novice andmore experienced green-house grower with awealth of useful informa-tion from the author'sown experience. It con-tains a good discussion ofindividual crops which in-cludes vegetables, fruits,flowers, and herbs.
Mastalerz, John, TheGreenhouse Environment:The Effect of Environmen-tal Factors on FlowerCrops, John Wiley andSons, Inc., New York, NY,1977. Although the focusof this book is on flowercrops, the general themeof the effects of environ-mental factors in thegreenhouse makes this anextremely valuable refer-ence. This is a text book,so the approach is techni-cal but readable.
Brady, Nyle C., The Na-ture and Property of Soils,MacMillan Publishing Co.,New York, NY, 1974. Thistextbook is a definitive,technical source of infor-mation on soils. Anyoneseriously interested inlearning more about soilsshould read it.
Brooklyn Botanical Gar-dens, Handbook on Bio-logical Control of PlantPests, Brooklyn, NY, 1979.This small, nicely done'publication with goodphotographs is a compen-dium of various articles onbiological controls. It is anexcellent introduction tothe subject.
Yepson, Roger B., ed.,Organic Plant Protection,Rodale Press, Inc., Em-maus, PA, 1976. Despitethe focus on gardeningoutdoors, this book willprovide the greenhousegrower with much usefulinformation for plant pro-tection using non-toxic,environmentally sensitive
35methods.
3 7
WRITTEN MATERIALSC
Beckford, Elwood andStuart Dunn, Lighting forPlant Growth, The KentState University Press,Kent, OH, 1972. This is avery technical book whichincludes excellent discus-sions of the physiologicalresponses of plants to lightsuch as phototropism andthe role of light in photo-synthesis. A good portionof the book deals with ar-tificial lighting. The bookis valuable to anyone in-terested in supplementallighting techniques.
Douglas, James, Begin-ner's Guide to Hydropon-ics, Drake Publishers, Inc.,New York, NY, 1973. Thisbook provides a briefoverview of hydroponicgrowing techniques usingchemical fertilizer solu-tions and includes discus-sions of appropriate flowerand vegetable crops.
Moody, Robert J., JohnR. McBride, and Mac-Donald Homer, ThermalPerformance and Horti-cultural Production of anAttached Solar GreenhouseIn a Severe Northern Cli-mate, National Center forAppropriate Technology,Butte, MT, 1982, in Pro-ceedings of the Energy '82Conference, Regina, Saskat-chewan, Canada. Thistechnical paper presentsNCAT's experience inoperating a small attachedsolar greenhouse. Informa-tion is included on theperformince of variousvarieties in the green-house.
Every year theGovernmentpublishes thousands ofbooks. And every yearthe Government Printing Office sellsmillions of these books to people in theknow. Now there's a book that tells youabout the Government's "`bestsellers"but it's not for sale . . . it's free!
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