CE Database subject headings: Sustainable development; Arizona; Measurement; Energy consumption; Water use; Constructionindustry.
Author keywords: Sustainable development; Arizona; Postoccupancy survey; Building consumption; LEED credits; Measurement;Energy consumption; Water consumption; U.S. Green Building Council.
Introduction
The USGBC LEED NC rating system was born out of a generallyaccepted recognition of humanity’s environmental impact. As such,LEED and other green building rating systems have attempted todirect the construction industry towards more sustainable designand construction practices. Since 1997, the LEED NC systemhas gained substantial popularity and is now the most prominentholistic, green building rating system in the United States.
The LEED NC rating system’s growth and tremendous presencein the green building market has resulted in ongoing industry scru-tiny. Despite several failed attempts to conclusively associateLEED and demonstrated energy efficiency, no study has attemptedto analyze the credits attained by a single population (Diamondet al. 2006; Lockwood 2006, 2008; Turner 2006; Turner andFrankel 2008; PNNL 2008; USGSA 2009; Walraven 2007).
Although many people are excited about the prospect of wide-spread LEED NC industry acceptance, others maintain opinions ofstiff opposition (Dunn and Makela 2008; Gershman 2009; Gifford2009; Scofield 2009). Because of the apparent chasm between thetwo sides, demonstrating efficiencies during this early period forthe fledgling green building industry is especially critical. Withno generally accepted study substantiating efficiencies, any uniden-tified inefficient or detrimental practices could continue erodingintended ecological benefits. Should a large-scale study of LEEDstructures fail to demonstrate expected results or return perfor-mances below anticipated levels, the construction industry mayreject LEED or green building philosophy in its entirety. Withthe USGBC forecasting over 100,000 commercial and one millionresidential structures by the end of 2010, the industry cannot affordto replicate caustic strategies and features on a large scale(USGBC 2009).
Objectives
A general lack of industry data regarding the performance and op-erations of both the overall LEED NC population and those thatoperate within primarily hot and dry climates directed the researchtowards Arizona’s LEED NC population. The intention was to con-tribute to a regional understanding of new construction LEEDcredit patterns, and determine if there were correlations betweencredits, utility consumption and both facility management and oc-cupant behaviors. This was accomplished by examining Arizona’s
1Assistant Professor, Del E. Web School of Construction, Arizona StateUniv., P.O. Box 0204, Tempe, AZ 85287. E-mail: [email protected]
2Ph.D. Student, Del E. Web School of Construction, Arizona StateUniv., 7037 E. Vernon Ave., Scottsdale, AZ 85257 (corresponding author).E-mail: [email protected]
LEED NC 2.0, NC 2.1 and 2.2 structures that had been in operationfor at least 12 months as of October 2009.
Methodology
After completing a comprehensive literature review of greenconstruction and various rating systems, a void of demonstratedLEED NC energy performance and published LEED credit trendsemerged. To collect the data required for analysis of the ArizonaLEED NC population, the authors’ research mandated creation of adata collection tool and an implementation strategy. Data collectionalso included identifying and directly contacting whomever pos-sessed the most intimate knowledge of the facility’s operations,a position commonly held by the LEED NC facility manager.
After establishing contact, efforts were extended to locate,collect and centralize all final LEED credit checklists. Efforts werefurther extended to distribute, monitor and collect a survey target-ing one year of utility data, and several operations and facility usagequestions. The majority of credit scorecards were downloaded fromthe USGBC website, with the remainder coming from owners,managers, architects, engineers or LEED consultants. Comprisedof 53 structures at initiation of data collection efforts, Arizona’sLEED NC population yielded the following deliverables as apopulation percentage:• LEED NC scorecards for 91% of the population.• Complete energy performance data for 47% of the population.• Complete water data and credit submission templates from zero
buildings.• At least partial operations-related responses for 71% of the
population.LEED credit analysis was then performed to identify credit
and utilization trends, intra-credit correlations, consultant-relatedinfluence on certification strategy and utility correlations.
Literature Review
The literature review identified the USGBC’s LEED system as themost ubiquitous, holistic green building rating system. This sectiondiscusses studies related to the performance of the LEED NC sys-tem, which judges buildings at a holistic level prior to occupancy.
Required by a multitude of federal, state and municipal buildingpolicies, LEED continues to rapidly expand. As of August 2009,1,946 LEED NC projects had been certified and 15,000 more hadapplied for certification (Navarro 2009). As of October 2009,35,000 projects were participating in the LEED system as regis-tered projects, “comprising over 4.5 billion square feet of construc-tion space in all 50 states and 91 countries” (USGBC 2009).
Because the USGBC continually fine-tunes LEED in an attemptto create ever improving, sustainable structures, its 12 year journeyhas led to five LEED NC iterations. Until the new LEED 3.0 ratingsystem was released in April 2009, none of the first four LEED NCversions incorporated credits that specifically accounted for region-specific concerns and characteristics.
The LEED system awards credits based on review and success-ful acceptance of various project aspects, which are intended tominimize environmental impacts. A building can achieve up to69 credits or points by attempting to minimize the building’s eco-logical footprint through resource conservation and creation of ahealthy and user-friendly environment for occupants. A project tar-geting basic certification under LEED NC 2.0, 2.1 or 2.2 mustachieve at least 26 credits to qualify as a certified LEED structure.Once credit thresholds of 33, 39 and 52 points are met, a building isawarded a silver, gold or platinum designation. The 69 credits are
allocated in the follow manner: sustainable sites (SS), water effi-ciency (WE), energy and atmosphere (EA), materials and resources(MR), indoor environmental quality (EQ), and innovation anddesign (ID) credits account for 14, 5, 17, 13, 15, and 5 points,respectively (USGBC 2005).
As the largest credit category, EA is intended to minimize abuilding’s energy demands and encourage renewable energy use.EA allocates 10 of its 17 available credits to the optimizing energyperformance category of credits (EAc1) by harnessing various en-ergy demand reduction strategies. Although there are two optionsfor receiving EAc1 credits, the most common is based on thepercentage improvement of a building’s simulated design case per-formance relative to its simulated baseline code performance.
For the simulation option, the baseline code for LEED NC 2.0and 2.1 was American Society of Heating, Refrigerating, and AirConditioning Engineers (ASHRAE) 90.1–1999, whereas the base-line for LEED 2.2 was ASHRAE 90.1–2004. A credit is awardedfor incremental improvements of 3.5%, starting at a 3.5% improve-ment relative to the base case simulation and ending at 10 possiblepoints for demonstration of 35% improvement (USGBC 2005).Energy simulations rely on myriad building performance assump-tions, which can have substantial effects on modeled performance.Assumptions associated with variability include energy and utilityrates, operational hours, number of occupants, activities held withinthe building, interior temperatures and assumed plug load. Plugload, typically assumed to consume 25% of a building’s energywhen following ASHRAE defaults, is typically a highly variableassumption because it is a best guess as to how the occupant willutilize the building. Relying on assumptions may then create sce-narios in which slight operational or utilization deviations result inconsumption outside simulated values.
Studies referenced within this paper utilize a few descriptivemetrics that require additional explanation. A building’s energyuse can be measured with either site- or source-based consumptionmetrics. Although site energy consists of the measured energyconsumption at the building’s meter, source energy considers allenergy required to produce the unit of energy consumed at thebuilding’s meter. Because various energies demonstrate vastly dif-ferent generation, transmission, distribution and storage efficien-cies, ratios must be applied to each source fuel to standardizemeasurement of a building’s total source-based energy consump-tion. Understanding these concepts is critical when holisticallyevaluating a building’s energy performance and overall carbonfootprint. This paper will also reference energy use intensity(EUI), a standardized unit of energy utilization which can be usedto describe either site or source energy consumption. EUI consistsof the building’s total kilo British thermal units (kBtu) divided bythe building’s gross square footage (GSF), and facilitates energyefficiency comparisons across buildings of varying size.
LEED evaluates site energy consumption when determininga project’s deserved energy credits. Other systems, such as theDepartment of Energy’s Energy Star program, evaluate buildingsbased on approximations of actual source energy usage (EPA2009). When excluding renewable energy, a building that consumes100% electric power under the LEED system will receive thesame number of credits as one that incorporates more efficient formsof primary and secondary energies, such as natural gas and steam.
Energy Performance and LEED NC CreditCorrelations
A follow-up analysis to a 221 building study performed by theNew Buildings Institute (NBI) compared the performance of each
building against its energy and atmosphere optimize energy perfor-mance credits (EAc1). According to the Institute for Research inConstruction, which operates within the National Research CouncilCanada, neither the number of EAc1 credits nor the LEED certif-ication level demonstrated sufficient correlation to the building’sactual energy use (Newsham et al. 2009).
The NBI study also focused on four LEED credits outside ofEAc1 to determine if there were any indirect correlations withenergy performance. The analyzed credits were additional commis-sioning (EAc3), measurement and verification (EAc5), and day-lighting and views (EQc8.1 and 8.2). The study found nostatistically credible relationship between any of the four evaluatedcredits and building energy performance. The authors of the NBIstudy also found that the lack of a correlation with EQc8.1 mayhave resulted from an increase in sunlight exposure without effec-tively controlling interior lighting systems. The study’s authorsbelieved this unintended energy increase resulted from EQc8.1not requiring an automatic lighting control system to maximizethe energy savings associated with daylighting.
An LEED survey performed in 2006 returned similar findings,but reported no correlation between power consumption and totalenergy and atmosphere credits. “When we looked at the data wesaw no correlation between energy efficiency points and actualnormalized performance for the buildings, with similar findingsfor the total LEED energy points” (Diamond 2006).
Data Collection
Retrieval of the final LEED credit scorecard or checklist provedeasiest because of the myriad possible information attainmentroutes. The 91% success rate resulted from leveraging the USGBCproject directory, contacting construction consultants, contactingbuilding facility managers, calling the building’s business officeand e-mailing the local USGBC chapter. Failure to retrieve the finalfive credit scorecards was driven by a lack of response from twobuilding contacts and an inability to determine contacts for threeothers.
A 71% operational survey retrieval rate required great persist-ence. Barriers typically related to the intimidating survey length,which extended to five full pages of questions. Only a few sectionsof the survey are relevant to and presented by this paper.
Water consumption data collection proved disappointing.Although 25% of buildings provided some form of usage data,none provided LEED NC water templates and few were able todifferentiate between building and landscape consumption. Thesecomplexities eliminated any chance of a normalized analysis. Ingeneral, few buildings tracked water consumption. Furthermore,structures on larger campuses rarely included dedicated buildingmeters and most were unable to track landscape and building con-sumption separately. The lack of results was surprising, especiallysince water efficiency credits were some of the Arizona LEED NCpopulation’s most commonly awarded credits.
Power consumption data collection efforts returned completedata for 47% of the population. The remaining 53% consisted
of four buildings that returned partial energy use data, 10 buildingsthat either never responded to the barrage of utility data inquiries orthose for which no contact was established, seven that opted out ofparticipation, four that had no dedicated meter on the LEED certi-fied building and three that simply did not track energy use andpossessed no utility records. General explanations given for notparticipating in data collection efforts included not having enoughstaff to accommodate the request, not being able to compile theinformation within the research’s timeframe, not returning dataafter committing to participate and not responding to participationrequests.
Data Characteristics
The LEED NC population’s 53 structures represented over 5.4 mil-lion gross square feet. These 53 buildings were the only LEEDNC 2.0, 2.1 and 2.2 structures known in Arizona when the datacollection tool was distributed in September 2009. Because of thesmall population size, analysis of each LEED NC version to creditperformance resulted in statistically insignificant differences. Addi-tionally, this study did not explore the possible impact of version2.0 that utilizes an earlier ASHRAE code baseline. Several build-ings that gained certification during data collection efforts were notincluded in the population. The population did include one confi-dential project that was not published on the USGBC website.
The 53-building population that existed when the data collectiontool was distributed included three LEED NC 2.0 buildings, 37LEED NC 2.1 buildings and 13 LEED NC 2.2 buildings. Goldcertifications were the most frequent at 43% of the population, fol-lowed by silver, certified and platinum with respective associatedpercentages of 25, 23 and 9.
Data Analysis
Analysis of LEED Credits for the 53-BuildingPopulation
As stated previously, credit collection efforts were successful for91% of the population, equating to 48 LEED NC credit scorecards.This section presents analysis of the overall credit distribution,credits awarded at various stages of LEED certification, the mostcommon and least common credits, regional LEED consultantimpacts and innovation and design patterns.
Table 1 displays the average number of credits per LEED NCcategory that the 48 building data set achieved. As displayed in thetable, the actual credits achieved from water efficiency, environ-mental quality and innovation and design as a percentage of totalcredits achieved exceeded the system’s 69 point credit distribution,whereas energy and atmosphere and materials and resources bothreceived less interest. The sections that were most frequently lever-aged were innovation and design, followed by water efficiency.
The WE and ID trend was reinforced when evaluating the 20most common individual credits. Innovation and design and water
Table 1. Credit Distribution for Arizona’s 48 Energy and Environmental Design for New Construction Scorecards
Credits SS WE EA MR EQ II Total
Average credits earned 7.4 3.5 8.1 5.4 9.3 4.2 37.9Total available credits 14 5 17 13 15 5 69Percentage of possible credits earned 53 71 48 41 62 83 55Average credits earned as a percentage of total average credits earned 20 9 21 14 25 11 100Available credits as a percentage of 69 possible credits 20 7 25 19 22 7 100
efficiency represented the largest percentage of available credits byplacing four ID and four WE credits, equating to 80% and 60% ofthose possible, respectively, in the top 29% of total available cred-its. Furthermore, WE and ID credits combined to represent four ofthe five most common credits and six of the ten most common cred-its. Dramatic underperformers included the energy and atmosphereand sustainable sites categories, which represented 18 and 14% ofpossible categorical credits, respectively. Besides three EAc1 cred-its, no EA credits were represented in the top 20. Fig. 1 displays abreakout of the 20 most frequently achieved LEED credits.
Twenty-one of the least commonly earned credits were analyzedafter two credits tied for the 20th position. Materials and resourcesand EA credits dominated the bottom 21. Placing six credits in thebottom 21, MR accounted for the six least common credits anddemonstrated zero occurrences of credit MRc1.3, “building reuse:maintain 50% of interior nonstructural elements.” Despite MR’sunderutilization by placing 46% of available MR points in thebottom 21 credits, EA accounted for the highest percentage with47% of those available, equating to eight credits. Excluding the 10potential EAc1 credits, five of the remaining seven EA credits, or86%, were represented in the bottom 21. Fig. 2 displays the break-out of the 21 least common credits.
Reviewing credits by level of certification clarified and confusedvarious elements of the 20 most common and 21 least commonbreakout analysis. Fig. 3 displays the interval percentage of themaximum number of possible credits attained by level of certifica-tion for each credit category, whereas Table 2 ranks the individualcredits in the order they were targeted across the certification gra-dient. Since Fig. 3 displays the credits that were harnessed to reachthe threshold of each certification level, the credits attained by plati-num buildings above 52 credits were excluded from the analysis.
Fig. 3 demonstrates that most projects target SS, WE and IDcredits to achieve basic certification. Although this supports thetop 20 and bottom 21 results for WE and ID, it is a direct contra-diction for SS. After reviewing the data more closely, it simplyseems that the population’s certified buildings chose SS with muchgreater frequency than those of higher certification levels. Therewere also a small group of SS credits that were just outside thefringe of the top 20, representing four of the next 10 and sevenof the next 20 most commonly awarded credits.
Once a project begins to move towards silver designation, alltargeted credits came from the EA, EQ and ID categories. Of these,
60%
70%
80%
90%
100%
ID: 2
WE
: 1.1
WE
: 3.1
EA
: 1.1
ID: 1
.1
EA
: 1.2
EQ
: 4.1
ID: 1
.2
WE
: 3.2
MR
: 4.1
MR
: 5.1
EQ
: 4.3
EQ
: 4.2
SS
: 1
MR
: 2.1
EA
: 1.3
MR
: 4.2
EQ
: 7.1
SS
: 4.2
ID: 1
.3
% of 48 Bldgs
Fig. 1. Twenty most commonly earned credits
0%
5%
10%
15%
20%
25%
30%
35%
40%
EQ
: 2
EQ
: 8.1
EA
: 6
SS
: 6.2
EA
: 2.1
EA
: 5
EQ
: 6.2
WE
: 2
EA
: 1.8
SS
: 2
EA
: 1.9
EA
: 2.2
EA
: 1.1
0
SS
3
EA
: 2.3
MR
: 6
MR
: 1.1
MR
: 1.2
MR
: 3.1
MR
: 3.2
MR
: 1.3
Fig. 2. Twenty-one least commonly earned credits
Fig. 3. Percentage of possible categorical credits by each certificationlevel’s threshold
Table 2. Order of Credits Awarded to Achieve Each Certification Level’sThreshold
four, two, and one were awarded in the EA, EQ, and ID schemes,respectively.
The six credit jump to gold primarily involved EQ with threecredits, whereas single credits were added within the EA, ID andSS sections. A project that was intended to become LEED Platinumprimarily targeted the EA category in adding five of the 13 neces-sary credits. EQ and SS contribute three credits each, whereas MRand WE add single credits. Very little activity is typically seenacross ID and WE credits, as these have mostly been exhaustedin reaching a gold level of certification. Very few MR credits weretargeted in reaching platinum certification, leaving six of thecategory’s 13 possible points nonutilized and thereby reinforcingthe MR credit trend observed in Fig. 2.
Energy and Atmosphere–Optimized EnergyPerformance Credits
The distribution of EAc1 credits attained by the 48 building data setwas relatively even, with six credits representing the highest fre-quency and 5.5 representing the mean. Although these averagesare respectable, Fig. 3 demonstrates that few of Arizona’s LEEDNC structures prioritize EAc1 credits when the decision is madeto attain basic LEED certification.
Energy Correlations
The 25 building energy group’s performance was tested to deter-mine if certain credits and credit combinations correlated withenergy consumption. Tested performance metrics included siteand source EUI, GSF, several operational variables, total numberof awarded LEED credits, total number of credits within each cat-egory, total number of EAc1 credits and all individual credits.Excluding factors between which one might expect high correla-tions, such as total EAc1 credits to total EA credits, there wereonly a few weak, yet statistically significant, correlations. Creditsdemonstrating correlations with site energy use emerged fromthe SS and EQ categories, yet had no logical connection to energyconsumption. After further analysis, it became evident that creditsdemonstrating correlations were common amongst the heavydistribution of gold and platinum high-energy-intense buildings,thereby nullifying correlations to the total sample. Neither EA cred-its nor credit combinations correlated with energy performance.There were also no correlations to the credits of specific LEEDversions. Further analysis of medium-energy-intense structuresdemonstrated no credit-to-energy consumption correlations. Oatesand Sullivan (2011) discusses the study‘s energy correlations ingreater detail.
Common Innovation and Design Credits
Whereas Table 1 shows that 4.2 ID credits were achieved on aver-age for each of the 48 buildings with LEED scorecards, Table 3displays a detailed frequency distribution breakout by category
of IDc1 credits. The categorical distribution is very similar betweenthe 25 building energy group and that of the greater 48 buildingdata set. Because all 48 buildings achieved the IDc2 LEED accred-ited professional credit, it is not listed in Table 3.
Green education credits are the most common, with 62% of the48 building population. Surprisingly, during conversations with thepopulation’s various facility managers, few were aware if theirfacility actively sponsored a green educational component. Innova-tion credits relating to MR are the next most frequent with 29 cred-its, or 19% of the population’s 152 awarded credits. This is unusualbecause the MR category was the least frequently utilized categoryof all regular LEED credits. This either means that the establishedMR credits do not include credits that are relevant to Arizona’s builtenvironment or the flexible ID credits permit leveraging of MRcredits with lower thresholds. If the latter is true, then recycledcontent (MRc4) and local and regional materials (MRc5.1) arethe primary targets, as they accounted for 79% of all ID creditsassociated with MR credits. Fig. 4 demonstrates the breakdownof regular MR credits by certification level. The figure providesvisual evidence that certain credits are worth leveraging relativeto seeking the basic threshold of less popular credits.
Green housekeeping, the second most popular independent IDoption, was awarded to 35% of the 48 building data set. Sixteenpercent of the 152 IDc1 credits were either unknown or uniqueenough that they did not fall within one of the established LEEDcredit categories. More often than not, these credits were unknownbecause of a lack of detail on the final LEED scorecard. This lack ofdetail was unexpected for a rating system that executes great rigorwhen reviewing credit submissions and lists transparency as a guid-ing organizational principle. As shown in Table 3, the two LEEDcredit categories with the smallest IDc1 representation were energyand atmosphere with 7% and environmental quality representing2% of the total awarded credits. Green power was the least commonindependent ID option, representing only 1 of 152 awarded credits.
Similarly to WE credits, ID credits are highly leveraged when abuilding targets certification. Although many of these ID creditsmay provide an ecological benefit, they are either relatively easyto achieve when compared with the requirements associated withmost other credits or they are not audited for compliance. Perhapseither changing the most common ID credits into prerequisites orelevating related credit thresholds would serve to more evenly dis-tribute awarded credits. Green education and green housekeepingare two examples of simple, yet critical green credits that couldbecome prerequisites.
Consultant Impact
Multiple consultants, including architects, engineers and privatefirms, helped Arizona’s LEED building population navigate thecertification process. Although the projects were somewhat spreadamongst consultants, one firm seemed to process more buildingsthan others. The subject firm is highly regarded with respect toregional LEED and green building efforts. Consequently, buildingsmanaged by what will hereafter be termed the primary regional
Table 3. Innovation and Design Credit Distribution
Data setGreen
education MRUnknown/
other WEGreen
housekeeping SS EAGreenpower EQ
48-building data set number of credits 30 29 19 19 17 8 9 1 348-building data set percentage of total 22 21 14 14 13 6 7 1 225-building energy data set number of credits 17 15 15 12 7 7 3 1 125-building energy data set percentage of total 22 19 19 15 9 9 4 1 1
consultant (PRC) were separated from those managed by smaller orless specialized firms. Buildings associated with this latter group offirms, hereafter termed other consultants (OC), were evaluatedseparately from the PRC’s buildings to determine if there were ob-vious populational differences. With the exception of state fundedprojects, client distribution was similar for the two populations.Although state projects represented 18% of the OC population, theycomprised 43% of the PRC group. Although initial t-test analysisof the PRC and OC samples demonstrated significant differences,the uneven building distribution negated the results.
Fig. 5 suggests that the PRC provides LEED navigation forbuildings targeting higher certification levels, rendering the twobuilding populations across all certification levels too varied foroverall analysis. With the exception of two platinum buildings,Fig. 5 demonstrates that the PRC is quite adept with respect tooperation at credit level thresholds.
Although total populations were incomparable, the high distri-bution of gold certifications within both the PRC and the OC pop-ulations led to analysis of the gold subset. The PRC buildingsdemonstrated a statistically significant difference from the OCbuildings in total LEED credits attained and two individual creditsthat were again proven significant after normalizing each building’scredits to a percentage of the total awarded credits. OC structures
were 147% and 185% more likely to earn EQc3.2 (constructionIAQ management plan, before occupancy) and EAc3 (additionalcommissioning). Both EQc3.2 and EAc3 are linked to actions thatmaximize the quality of the final overall product and could beincorporated into to the specifications of every project. As the re-search did not cover a more detailed analysis of these two services,it will not comment on any resultant value to either the owner or theoccupant. The PRC sample exhibited dominance in 2 EA credits:EAc2.2 (10% renewable energy) and EAc4 (enhanced refrigerantmanagement, ozone depletion). Although EAc2.2 represents a com-mitment to generate onsite renewable power, sufficient manipula-tion of the design or proposed energy model helps facilitateminimal generation to achieve this credit. The PRC structuresearned this credit with 75% greater frequency than that of theOC structures. No OC buildings achieved the EAc4 credit, whereas25% of the PRC structures did earn the credit. The EAc4 creditmandates the use of either no refrigerants or selection of refriger-ants that have either minimal or no ozone-depleting or globalwarming compounds. This credit requires the usage of complexformulas which may act as a barrier to less experienced consultants.
The gold PRC buildings demonstrated a mean of 40 credits, onegreater than the 39 point gold threshold and 1.78 credits less thanthe average OC structures. This definitively exemplifies the PRC’s
Fig. 5. Certified building population by consultant
Fig. 4. Percentage of possible MR credits attained by certification level
skill in minimizes superfluous targeted credits when ensuringagainst possible negative USGBC credit rulings. This skill-set iscritical when trying to spend the least amount of money for aspecific certification level.
Two patterns observed during graphical analysis are worth not-ing. Whereas both PRC and OC populations targeted optimizedenergy credits, PRC building energy focus dropped dramaticallyafter EAc1.7. Whereas 43% and then 36% of the OC buildings at-tained EAc1.8 and EAc1.9, only 13% of the PRC group receivedthe same credits.
Practical Utilization of Credits
The survey also collected facility managers’ best guess responsesto several occupant behavior questions. The categories included sub-jects of recycling, health and utilization of alternative transportation.
The facility of every surveyed building, with one exception,stated their facility operated a recycling program. The exceptioninvolved a facility manager who gave a not sure response. EveryLEED NC building should have dedicated a certain amount ofspace to collection and storage of recyclables under the materialand resources sections’ recycling prerequisite.
The 38 building survey response group received 13 total inno-vation and design credits for operating green housekeeping prac-tices. Consideration for green housekeeping typically requires aholistic, green cleaning program rather than simply using a fewnontoxic cleaning products. Interestingly enough, only two ofthe buildings that received the green housekeeping ID creditclaimed to operate a green cleaning program, whereas many build-ings that did not receive the green cleaning credit reported usingsuch a program. In fact, 71% of survey respondents claimed theirrespective buildings used some form of green cleaning program,over double the number receiving the associated credit. Moreencouragingly, 89% of the 38 survey respondents stated their fa-cility housekeeping staff utilized at least some green products. Thisdemonstrates that although buildings may not operate an officialLEED green housekeeping program, building owners and operatorsvalue high quality interior air enough to choose green cleaningproducts regardless of the LEED credit.
Seventy-two percent of 36 survey respondents stated their fa-cility operated an alternative transportation incentive program.These 26 respondents reported that 18.2% of all occupants wereusing some form of alternative transportation. Those structures run-ning alternative transportation incentive programs stated that 20.1%of occupants utilized alternative means of transportation, as op-posed to only 10.4% of occupants without such a program. Surveyrespondents of buildings that achieved SSc4.1 (public transporta-tion access) reported that 5% of the building’s occupants utilizedpublic transportation, as opposed to only 1.4% in buildings that didnot achieve credit SSc4.1. This demonstrated that occupants wouldtake advantage of public transportation options if afforded to themby the building’s location. Of those that achieved SSc4.1, threebuildings reported that no occupants utilized public transportation,and eight buildings were not aware of people using public trans-portation. Many of the latter were on campuses in which the build-ing’s facility manager was not able to discern occupant travelpatterns. LEED NC structures that achieved SSc4.2 (bicycle stor-age and changing rooms) averaged 2.7% occupant utilization, ver-sus 1.3% utilization by those that did not received credit SSc4.2.Of those that received SSc4.2, seven buildings did not report anyusage. With respect to SSc4.3 (low emission and fuel efficientvehicles), there was no statistically significant utilization differencebetween those buildings that either did or did not achieve the credit.
The average for both samples was approximately 3%. No statisti-cally significant difference emerged from the comparison of thecarpool percentage in buildings that had achieved SSC4.4 (parkingcapacity) versus those that had not. The averages for both sampleswere approximately 4%. These results demonstrate that althoughcredits SSc1 and SSc2 correlate with increased alternative transpor-tation utilization, SSc3 and SSc4 do not. For the latter two credits,perhaps the credits should be given to buildings pledging to operatean alternative transportation incentive program, as opposed to thosesimply allocating parking spaces to certain vehicle types.
Analysis Summary
Minimal water management within the population resulted in weakdata collection, thereby leaving the water performance of Arizona’sLEED buildings uncertain. This lack of active water managementwas surprising after determining that water efficiency credits were aheavily weighted priority within Arizona’s LEED NC population.This disconnect is interesting, especially amongst buildings pur-porting to be green within a desert setting.
Analysis of credits achieved by 91% of the Arizona LEED NCpopulation identified several trends. It was apparent that water ef-ficiency, innovation and design, and indoor environmental qualitywere early credit targets, whereas energy and atmosphere only be-came a priority at higher levels of certification. The underutilizationof materials and resources within the Arizona population was high-lighted when 46% of MR credits appeared within the ranks of the21 least frequently achieved credits. Underutilized credits associ-ated with energy performance, such as energy and atmosphere, mayrequire heavier weighting to incentivize attainment. Credits leastfrequently utilized in Arizona should either be removed or alteredto render them more relevant or more appealing to developers.
The analysis returned few correlations between credit and en-ergy consumption. The lack of statistical significance linking allforms of energy and atmosphere credits, especially total optimizedenergy performance credits, to energy consumption was surprisingconsidering efficiency is their primary purpose. Attempts to corre-late energy performance with other credits also returned nullresults.
Analysis revealed the impact imparted by LEED consultants,highlighting how experience and deep system understanding resultsin a highly efficient and successful credit attainment strategy.
The research also demonstrated that the building’s occupantswere utilizing many of the features associated with LEED NC cred-its. Those features that did not appear to catalyze significant utiliza-tion included dedication of parking spaces for hybrid vehicles andcarpools. Therefore, SSc4.3 and SSc4.4 features might experiencehigher levels of utilization if they were linked to management of analternative transportation incentive program rather than simplededication of parking spaces. Several buildings that received greencleaning credits did not employ green cleaning programs, yet twiceas many buildings as those that received the green cleaning creditclaimed to operate green cleaning programs. This result introducesthe concept that most operators and owners are cognizant of indoorair quality.
Conclusion
The concept of green building has both its fervent supporters anddiehard detractors. If there were truth to both parties’ beliefs, greenbuilding would create value at an uncertain cost while potentiallyresulting in uncertain drawbacks. Although countless peoplebelieve that green buildings are unwaveringly positive for the
environment, owners, operators and occupants, data has yet to showthat all green building strategies catalyze benefits. This analysisreturned a broad range of results that only reinforce the debateby both supporting and criticizing components of the LEED ratingsystem’s methodology.
The study’s results demonstrate to industry practitioners andresearchers that the 69 point LEED NC rating system fails to dem-onstrate substantial correlations between energy use and credits,thereby discounting energy conservation strategies inherent inLEED NC versions 2.0, 2.1 and 2.2. The results also highlightthe need to incentivize those credits which produce the greatestenvironmental benefit across the building’s full life cycle.
Unfortunately, future study of LEED credits will prove moredifficult as it will require collection from each project rather thanfrom the USGBC website. This hindrance was established in thefall of 2009 when the USGBC decided to no longer publish score-cards for all listed projects, effectively contradicting one of theirpublicized guiding principles (exhibit transparency), which in-cludes striving “for honesty, openness and transparency.” Althoughthe USGBC is open and democratic with respect to the creation andrevision of its various rating systems, opacity exists when relatingto particular buildings or clients. If achieving LEED was trulysomething about which to be proud, publicizing the detailed score-card is only logical, as publication enables the public to betterunderstand the quality aspects of each LEED project. Because prin-ciples inherent in LEED can be utilized to construct a holisticallysustainable structure without certification, the primary purpose forattaining LEED is to be recognized in the open market. Excludingbuildings that feature valid security or confidentiality constraints,the only logical cause for an owner to hide the scorecard frompublic scrutiny is failure to choose truly sustainable credits.
This paper was intended solely to evaluate Arizona LEED struc-tures at a broad level in the hope of identifying performing anddeficient aspects of green construction. Further study would bebeneficial to better understand holistic green building performance,especially within hot and arid climates. It is the authors’ hope thatthis paper may have a positive impact on development, constructionand operational strategies utilized by future green buildingsconstructed within the southwestern desert, thereby assisting thecontinued performance and reliability improvements of desert-dwelling facilities.
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