15_RecentProgressPassiveCoolingTechniques_Kostas

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Santamouris et al Recent Progress on Passive Cooling Techniques

PREA Workshop 2006 - 1 -

Recent Progress on Passive Cooling Techniques.Advanced Technological Developments to Improve Indoor Environmental Quality in Low

Income Households

M. Santamouris, C. Pavlou, A. Syneffa and K. Niachou

Group Building Environmental Studies, Physics Department, Univ. Athens, Athens, Greece,mail : [email protected]

Abstract

Low income households in developed and less developed countries suffer from serious indoorenvironmental problems like heat stress, lack of comfort and poor indoor air quality. This has avery serious impact on the quality of life and health of poor citizens. More than 2 million deathsper year are attributable to indoor air pollution from non adequate use of fuels, while thousandsof low income citizen dies because of high indoor temperatures.

Passive cooling of buildings and in particular solar and heat protection techniques, heatdissipation and heat amortisation techniques have reached a very high degree of maturity. Newtechnological developments have been proven extremely efficient to decrease the needs forcooling and improve indoor environmental conditions. Developments on the field of solar andheat protection like the high reflective coatings for the building envelope and new knowledgeand developments on the field of convective cooling and ventilation may help considerably lowincome citizens to improve their quality of life during the overheating period. New developmentsare characterised by low cost and are easy to apply.

The paper investigates the potential of cool reflective coatings to improve indoor conditions oflow income households in warm areas of the planet while it discusses the potential of newventilation techniques and systems to improve indoor comfort and air quality. Results show a

very high potential to improve indoor environmental conditions and contribute towards higherpassive survivability levels.

Introduction

Buildings is the major economic sector in the world and the quality of buildings shapes the lifeof citizens. Although there is an important increase of the budget devoted to construction,United Nations estimates, (1), that more than one billion of urban citizens, live in nonappropriate houses mostly in squatter and slum settlements, while in most of cities in lessdeveloped countries between one and two thirds of the population live in poor quality andovercrowded housing, (2), with insufficient water supply inadequate or no sanitation, nonappropriate rubbish collection, no electricity and energy networks and under the risk of flooding

and other environmental phenomena, (3).

In the developed world, the percentage of people living in low income households is quite high.The average percentage of low income households in EU is close to 15 %, while in somecountries it may go up to 21 %, like in Ireland, (4).

Non appropriate housing is characterised by poor indoor environmental conditions, likeextremely low or high temperatures, luck of ventilation, etc. In parallel, heat island conditions indense urban areas increase ambient temperatures and the thermal stress to buildings mainlyduring the summer period, (5). It is characteristic that in Athens, heat island increases thecooling load of buildings by about 100 per cent, (6), while heat island is mainly present in zonesof cities where low income people is living, (7).


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Non appropriate design of buildings, increase of the urban temperatures and improvement ofliving standards have contributed to a spectacular increase of the air conditioning penetration inthe residential sector. According to the IEA, (8), energy demand for residential space coolingaccounted for 6.4% of total electricity demand in the OECD in 2000 and there was a 13%growth from 1990 to 2000. As reported by Waide (9), almost 46% of OECD households have

some air conditioning, but this varies widely from continent to continent and country to country.In the US up to 80% of new homes have central a/c systems, while the share of air conditionedhouses increased from 23% in 1978 to 77% in 2001. In Europe the penetration is quite low,around .02 per household on average, but there was a 7-fold increase over the 1990s and now

AC saturation could be around 5-7% of households.

Increased use of air conditioning, creates a serious peak electricity load problem to utilities andincreases the cost of electricity. According to OFFER and National Audit Office, (10), the meanEuropean cost of a kWh out of peak is close to 3,9 cents, while the mean cost during peak is10,2 cents. In parallel, the average cost of a saved kWh is 2.6 cents. In parallel, strengthincreases highly during heat weaves. As reported, during the July 2006 heat wave in California,

the average homeowner used about 28 percent more electricity, (11).Increase of the necessary energy load to satisfy appropriate indoor environmental conditions inpoor households, combined with increased energy prices, put a serious strength to low incomepeople. When more than 10 % of the family income is spend for energy, the family ischaracterized as energy poor, while when expenditures exceeds 20 per cent of the income,the family is under severe energy poverty. It is characteristic that only in UK almost 5.2 millionpeople are considered as energy poor, (12). In Ireland, estimations show that 17,6 % of thehouseholds are energy poor, (13), around 226000 houses. About 27 % of the fuel poor houses,around 4.7 % of the total housing stock, is suffering from chronic fuel poverty. Also, 12,7 % ofthe households suffer from intermittent levels of fuel poverty, i.e. occupants are occasionallyunable to condition their homes. In USA, a report published recently by the National Fuel Funds

Network (14), found that at the end of the 2000/2001 heating season, at least 4.3 million low-income households were at risk of having their utility service cut off because of an inability topay their home energy bills.

The situation regarding the environmental condition of households in less developed countriesis far to be acceptable. As reported by the United Nations, (15), in cities of the less developedworld, one out of every four households lives in poverty; 40 per cent of African urbanhouseholds and 25 per cent of Latin American urban households are living below locallydefined poverty lines.

Buildings in less developed countries are the major energy consumption sector. The share of atleast the residential sector has increased from 22.2 % to 34.4 % during the decade 1987-1997,(2). The amount of energy spent as well as the type of fuels used in the less developedcountries, is a strong function of their economic status. Low income people consume les costlyand less convenient fuels while as income rise more expensive and highly convenient types ofenergy are used. As reported by Waddams Price, (16), households are able to switch over tomodern fuels when their incomes reach $1000-1500, while a recent study, (17), carried outstudy in forty five cities of some less developed countries has shown that the lower incomepeople consumes less energy while they make use of less convenient energy sources likewood and charcoal. The situation has a serious impact on the household expenditures andincome, quality of life and health. It is estimated that the necessary investments to bring cleanenergy technologies in the urban areas of less developed countries are close to $40 billion

annually (1992 values), (18).


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It is evident that alternative energy and environmental solutions have to be adopted to improvethe environmental conditions of low income households. The idea is not to maintaintemperatures within the ASHRAE-defined comfort zone of (2027C) using energy drivensystems, but to create buildings that will not threaten the lives of their occupants under adverseambient conditions and even when if power is lost or citizens can not afford to pay for it, (19)..

Passive cooling relies to the use of solar and heat control techniques, heat amortisation andheat dissipation techniques. Intensive research carried out the last years on the topic, haspermitted to develop advanced and low cost systems and techniques that when appliedcontribute highly to decrease the cooling needs of buildings and improve indoor environmentalquality, (20).

In particular the development of high reflectivity coatings for the building envelope candecrease considerable the solar input to the buildings, while new developments on ventilationtechnology permits to dissipate successfully the excess heat to the ambient air, improve indoorcomfort and decrease indoor pollutants concentration. Both techniques are of low cost andsimple in their use.

The present paper discusses the applicability and investigates the potential contribution of bothtechniques for low income households facing problems of overheating and poor indoorenvironmental quality.

Indoor Environmental Quality of Low Income Households

Poor indoor environmental quality in low income households cause heat strokes, heart attacks,bronchitis, pneumonia and other heat related illnesses and respiratory diseases. Only in UKthere are around 40,000 excess winter deaths a year because of inappropriate indoortemperatures, (12, 21).

During the summer period, high ambient temperatures and heat waves cause dramatic

problems to vulnerable population living in overheated households. In France the estimateddeath toll of the 2003 heat wave was about 15000 deaths. According to the Eurosurvellance(22), an estimated 22 080 excess deaths occur in England and Wales, France, Italy andPortugal during and immediately after the heat waves of the summer of 2003. Additionally6595-8648 excess deaths have been registered in Spain, of which approximately 54% occurredin August, and 1400-2200 in the Netherlands, of which an estimated 500 occurred during theheat wave of 31 July-13 August. In parallel, it is reported that approximately 1 250 heat-relateddeaths occurred in Belgium during the summer of 2003, almost 975 excess deaths duringJune-August in Switzerland and 1 410 during the period August 1-24 in Baden-Wrttemberg,Germany. Studies in Europe and US, [22-25].show that the greatest excess in mortality wasregistered in those with low socioeconomic status leaving in buildings with improper heat

protection and ventilation..

During summer, high indoor temperatures and lack of proper ventilation are the sources ofimportant health problems. An important increase of mortality rates is observed in SouthernEuropean countries during the recent heat waves. The heat wave of August 2003 in Europehas been an extreme meteorological event with dramatic consequences. In France theestimated death toll of the event was about 15000 deaths. In Rome, excess mortality wasobserved throughout the summer, but predominantly during the three heat waves observed[23,24]. It has to be pointed out that the greatest excess in mortality was registered in thosewith low socioeconomic status in Rome (+17.8%), living in poor households.

Klinenberg (25) has focused on a July 1995 heat wave in Chicago, USA, that killed between

485 and 740 citizens. A large proportion of the victims used to live in Single Room Occupancy(SRO) buildings. It is reported that only about half of the residents had fans, and many lived in


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rooms with sealed windows they could not open. It is also reported that even if some of theelderly victims had had air conditioners in their homes, many would not have used thembecause they were not able to pay for their utility bills.

Non proper indoor environment and non adequate ventilation may be the source of importantsocial cost for additional health treatment. In a recent study, (26), the healthcare cost of peopleliving in 107 homes on a poor estate in East London were compared against those of peopleliving in homes in a similar improved estate. It is found that the average annual health costs ofa person living in the poor estate were 512, against 72 for a person in the improved estate.

Indoor environmental problems in less developed countries is a very serious problem. Asreported by the World Bank, (27), today about half the population of the world continues to relyfor cooking and associated space heating on simple household stoves using unprocessed solidfuels that have high emission factors for a range of health-damaging air pollutants. The use ofsuch fuels, produce 10-100 times more respirable particulate matter per meal, (27), whilemonitoring of indoor pollutants made in homes in India showed particulate levels 35 times theone hour standard and nearly 100 times the 24 hour standard recommended in industrialised

countries, (28).

As reported by Birol, (29), high indoor concentration of pollutants poses a tremendous healththreat to the population. Worldwide, close to 2 million deaths per year are attributable to indoorair pollution from cooking fires. Studies of the WHO have shown that 30 to 40 per cent of 760million cases of respiratory diseases world-wide are caused by particulate air pollution alone.Mostly, these health effects are caused by indoor air pollution due to open stove cooking andheating in developing countries (30). In particular in India, it is estimated that 500000 womenand children die each year due to Indoor Air Pollution related causes as almost 75 % of thepopulation relies to traditional biomass fuels, (31). This is close to 25 % of the deathsworldwide attributed to indoor air pollution problems. Other studies in Latin America, Asia, and

Africa have shown that indoor air pollution is also responsible for pregnancy-related problemssuch as stillbirths and low birth weight. It has also been associated with blindness (attributed to18 percent of cases in India) and immune system depression.(31).

Cool Materials to Protect the Thermal Envelope.

Solar absorption and transmission of heat through the building envelope increases thetemperature of the fabric as well as indoor ambient temperature. Thus, the cooling needs areincreasing, while the comfort levels are deteriorated. Use of coatings at the exterior faade ofbuildings presenting a high reflectivity to solar radiation and a high emissivity coefficientdecreases the absorption of solar radiation and increases the radiation losses. Coatingspresenting such a performance are known as cool materials, (32)

Two main types of cool coatings for roofs and exterior facades of buildings have beendeveloped. A) white coatings presenting a very high reflectivity to visible part of the solarradiation, (33), and colored coatings presenting a high reflectivity to the infrared part of thesolar radiation, (34,35).

Extensive outdoor testing of cool white coatings during the summer period has shown thatpresent almost 12 C lower surface temperatures than reflective aluminum paints, and morethan 16 C than silver gray reflective coatings, (33). In parallel, colored cool coatings testedoutdoors against conventional coatings of the same color, presented a reduction of the surfacetemperature up to 10 C, (35).

In order to evaluate the possible environmental benefits of the use of cool white coatingsapplied on the roof of low income households, simulations have been performed for 29 placesin Middle East, Africa and South America, Table 1. Positive values of the latitude indicate that


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the station is in the North hemisphere and negative values to the South hemisphere. Positivelongitude values means that the station is West of Greenwich and negative that it is East ofGreenwich.

Calculations have been performed for a whole meteorological year with an hourly time stepusing the precise thermal simulation software TRNSYS, (36). Meteorological data have beentaken from the METEONORM base, (37).

The simulated building is a single store building of 80 m2, having openings at its four facades.The surface of the considered building is for sure much higher than the typical low incomehouse. Given that, the lower the surface of the building, the higher the expected coolingcontribution because of the decreased heat transmission through the envelope, a much highersurface has been selected to avoid overstatement of the expected results.

Buildings have been considered as single glazed, well shaded, and non insulated presenting aU value equal to 4.3 W/m2/K for the roof and 2.3 W/m2/K for the walls. The exterior faade ofthe roofs was considered as covered with a high reflective white coating presenting an totalreflectivity to solar radiation equal to 0.9 and an emissivity coefficient close to 0.91.

Ventilation and infiltration rates have been set close to 1.6 ach. As it concerns internal gains,heat input per person has been considered according to ISO 7730, while for the artificiallighting and any other equipment it has been assumed that the 50% of the input is contributedto the pace as convective heat and the rest 50% as radiative.

Two types of calculations have been performed. Buildings are considered either at a constantindoor temperature, (26 C), or running under free floating conditions. For the first case thereduction of the considered cooling load has been calculated, while in the second case, theachieved reduction of the peak indoor temperature, as well as the reduction of thecorresponding number of hours above a certain indoor temperature have been estimated.

Table 2 gives the calculated cooling load per square meter for the conventional as well as forthe building with the reflective roof, for each place. As shown the expected absolute reductionof the cooling load varies between 5 to 70 kWh/m2, as a function of the local climatecharacteristics. Lower absolute contributions correspond to small cooling loads but represent ahigh percentage of the load, up to 70 %, while high absolute contributions correspond to highcooling loads and a lower relative reduction of the load, (> 20 %). As a mean value, the use ofreflective coatings in the roof of this type of buildings in the selected areas may decrease theircooling load up to 30-35 %. The cumulative frequency distributions of the cooling load ascalculated for both cases and for all the places are given in Figure 1. As shown, while for theconventional buildings, the 50 % of the distribution corresponds to a value close to 140kWh/m2/y, for the case of the building with the reflective roof this is reduced to 85 kWh/m2/y.

Table 3 gives the calculated number of hours with an indoor temperature above 30 C, 27.5 Cand 26 C. Data are given for the conventional and the reflective roof buildings. Results showthat for all temperature bases, a very important improvement of indoor comfort may beachieved by using reflective roofs. The specific reduction of the hours above a thresholdtemperature depends highly on the distribution of the ambient temperature during the day, andthe overall climatic conditions. Figure 2, gives the cumulative frequency distribution of the hoursabove the selected temperature base for both cases. As expected the higher the temperaturebase the higher the benefits. For the temperature base of 30 C, the 50 % of the distributioncorresponds to 3400 h and 1700 for the conventional and the reflective roof buildingrespectively. The corresponding values for the temperature base of 27.5 C are 6400 and 4400,

while for the base of 26 C the corresponding values are 7400 and 5800 respectively.


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Table 4, shows the calculated maximum indoor temperatures for both cases. As shown theexpected decrease of the maximum indoor temperature varies between 2.2 to 3.7 C. Figure 3,shows the cumulative frequency distribution of the maximum indoor temperatures for bothcases. The 50 % of the distribution for the conventional case corresponds to a temperatureclose to 39 C while for the building with a reflective roof the corresponding value is close to

36.1 C.It is evident that all above figures are indicative and may vary as a function of the buildingcharacteristics. However, the whole analysis permits to conclude that low cost reflective paintswhen used in the roof of low income households in hot climates, can contribute highly toimprove indoor environmental conditions and decrease the needs for cooling. Such a policyhas been already applied by the City of Philadelphia's, USA, under the frame of the "CoolHomes Program" for elderly low-income residents. The program provides non-mechanicalcooling measures that save energy and lower costs. The aims of the program involve thereduction of the indoor temperatures to a comfortable level, minimisation of health risks,stabilisation of the energy consumption and provision of social interaction. The program has

provided to all houses, a window mounted whole house fan, interior air sealing, and anelastomeric roof coating to decrease the roof temperature. It has been found that the employedmeasures lower the solar gains by 80 % and reduces the bedroom indoor temperatures by 2.5C. The estimated energy offer was equivalent to the energy delivered by a conventional airconditioner of 8 Kbtu/h, running for four hours per day,

Effective Ventilation for Heat Dissipation and Indoor A ir Quality

Important research has been carried out recently on appropriate and advanced ventilationtechniques, (38). The main achievement may be summarized in two main axes :

- Better understanding of the air flow phenomena and of the expected comfort benefits, inparticular in the dense urban environment, and development of efficient and practical

procedures to design natural and hybrid ventilation systems and configurations, (39,40),

- Technological developments mainly on the field of hybrid and mechanical ventilation thatcontribute highly to a more comfortable and healthy indoor environment, (41)

Understanding the air flow phenomena in the dense urban environment is of vital importance.The very rapid urbanization at the end of the century has increased the total number of urbancitizens up to 3 billions and it is expected to increase to about 5 billion by 2025, (42). However,according to the estimations of the World Bank, (43), almost 60 % of them will live below thepoverty line and most of them without access to electricity. Most of these people is living inpoorly designed buildings suffering from high indoor temperatures during summer. Thus,proper design of openings to achieve natural and night ventilation and decrease indoor

pollution is of extreme importance for this part of the population.

Extensive experimental and theoretical research to understand better the air flow phenomenain dense urban environments, (44), has permitted to develop simple and accurate models tocalculate the wind field in the canopy layer, (42, 45), and based on this to develop simple andaccurate sizing techniques for windows and other natural ventilation systems, (46)

Proper design of windows permits to increase air speed in households and improve comfort bycooling down the human body through the mechanisms of convection, radiation andperspiration. In parallel to increase air flow rates to achieve lower indoor temperatures, improveindoor air quality and health conditions. In particular,

Although the appropriate levels of air velocity to achieve comfort is a discussion topic for thescientific community, (47-49), recent studies performed in tropical climates, (50-52), confirm


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that increased air speed, especially at higher temperature enhances the thermal comfortconditions. According to Kukreja, (53), indoor air velocity, in warm climates, should be set at1.001.50 m/s. Hardiman, (54), proposes an air speed between 0.21.5 m/s for light activity.Hien and Tanamas, (52), report that undesirable effects of high air movements of above 3m/sec have been observed.

Night ventilation is one of the more efficient passive cooling techniques for low incomehouseholds. Golneshan and Yaghoubi, (55,56), report that the use of 12 ach per hour duringnight, with one ach during the day, may provide comfortable indoor conditions. Given that theurban environment decreases considerably the cooling potential of night ventilation, (57, 58),appropriate design of openings is very important.

Use of solar chimneys to enhance air flow in buildings is a well known technique that can beeasily integrated in low income households. Solar chimneys are natural draft components,using solar energy to build up stack pressure and thus a driving airflow through the chimneychannel. Solar chimneys can improve the ventilation rate in naturally ventilated buildings in hotclimates, (59,60). It is found that the impact of solar chimneys is substantial in inducing natural

ventilation for low wind speeds. Recent research has permitted to optimize the design andoperation of solar chimneys, (61-63), and thus to improve indoor environmental conditions inoverheated houses.

High outdoor air pollution and noise may be major drawbacks for natural ventilation systems.According to the United Nations Global Environmental monitoring system an annual average of1.25 billion of urban inhabitants are exposed to very high concentrations of suspended particlesand smoke, (64), while an other 625 million of urban citizens are exposed to non acceptableSO2 levels. It is characteristic than in Europe 70 to 80 percent of cities with more than 500000inhabitants, the levels of air pollution, regarding one or more pollutants exceeds the WHOstandards at least once in a typical year, (65) Noise is a second serious limitation for natural

ventilation in the urban environment. OECD, (66), has calculated that 130 millions of people inOECD countries are exposed to noise levels that are unacceptable.

New efficient design of box fans, oscillating or ceiling fans when used can increase the interiorair speed and improve comfort at very low cost. Wu et al, (67), have demonstrated the potentialof oscillating fans to extend the comfort zone. It is found that for an air speed of 1.52 m/sec,comfort is achieved at 31 C at 50 % relative humidity, or at 32 C at 39 %, or finally at 33 C at 30% relative humidity.

Rohles et al, (68) and Scheatzle et al, (69), have proven that ceiling fans can extend thecomfort zone outside the typical ASHRAE comfort zone. In particular at an air velocity of 1.02m/sec, comfort may be achieved at 27.7 C, for 73 % relative humidity, 29.6 C for 50 % humidity

and 31 C for 39 % relative humidity. Recent research has permitted to develop more efficientceiling fans. Schmidt and. Patterson, (70), have designed a new high efficiency ceiling fan thatcan decrease the power consumption and therefore electricity charges by a factor between twoand three, while Parker et al, (71) have designed a new very efficient ceiling fan of improvedaerodynamics blades that presents a much higher airflow performance.

As previously mentioned, indoor air quality because of inadequate use of fuel as well asbecause of other indoor and outdoor sources is a major problem for low income households. Indeveloped countries, the concentrations of indoor pollutants is very similar to those outdoors,with the ratio of indoor to outdoor concentration falling in the range 0.7-1.3. However,concentration of indoor pollutants may be two to five times higher that the outdoor one, (72).

According to United Nations Center for Human Settlements, indoor air quality is inadequate in30 % of the buildings around the world, (64).


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Searching for solutions, it seems that the use of appropriate and low cost hybrid ventilationsystems may be a very advantageous and can seriously help to improve indoor air quality andthermal comfort. Hybrid ventilation systems use both natural ventilation and mechanicalsystems, but employing different features of these systems at different times of the day orseason. (73).

Various hybrid ventilation systems for residential buildings, have been developed andproposed, (73). Testing of the systems has shown that in urban areas may be more effectivethan single side natural ventilation techniques, (74), while studies on indoor air quality haveshown that hybrid systems may be very effective to remove indoor pollution, (75).

A comparative analysis of the concentration of indoor pollutants in residences located in fivedeep canyons in Athens, when natural and hybrid ventilation systems are considered, hasshown that the levels of indoor TVOCs and CO2 concentrations are always lower when hybridsystems are used. The analysis has consider five different control strategies involving, simpleCO2 and TVOC;s control, combined CO2 and TVOCs control, control of the indoortemperature, (passive cooling), and combined control of the indoor temperature and the CO2

levels or control of the indoor temperature and TVOCs levels, (Figures 4-5).

Appropriate application of hybrid ventilation principles may be an efficient solution forhouseholds in developing countries experiencing a high indoor smoke concentration becauseof the use of inappropriate fuels. In this case the the main aim is simple : Remove the airpollution from homes. This can be achieved by a combination of appropriate openings andsimple fan assisted systems to remove smoke

Important applications aiming to improve indoor air quality in poor households have beendesigned and implemented by International Help Associations in Sudan, West Kenya andNepal. (76,77) In most of the places, windows were small or not adequately positioned toremove smoke and many times were closed off for security reasons and exclusion of animals.

Interventions involved among others, new hoods with flues as well larger and better positionedwindows and improved stoves.

Monitoring of the interventions has shown important reductions to smoke exposure. In Kenyathe reduction of the particulates and carbon monoxide was close to 80 %, and the exposure ofwomen was reduced by a quarter. The total time for which the women were exposed to levelsof CO greater than 9 ppm was reduced by around 60 % from around 2.5 hours to around 1hour. In parallel, it is found that the enlarged windows did have benefits, such as improvinglighting in the houses but did not add significantly to reduce indoor smoke.

Conclusions

Recent development on passive cooling technologies permit to improve the indoorenvironmental quality of low income households. High reflective coatings for buildings, presentlow cost, are easily accessible and when used may reduce substantially indoor temperaturesand enhance comfort in most of the warm zones of the planet. In parallel, recent knowledgeand developments on ventilation technologies permit to better design and position openings inurban buildings, enhance indoor air speed, improve indoor comfort and decrease indoorpollutants concentration.

It has to be clear that there is no unique solution for all people leaving in poor households. Thesuccessful implementation of the proposed new techniques and technologies depends uponthe active participation of the concerned population. As mentioned by the UNDP SL buildingpoor people's capacity to make technology choices is not just "bringing" new technologies to

their doorstep, but addressing their organisational, management and marketing skills; openingnew channels of information and knowledge and making credit and markets more accessible.


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It is important that any proposed technical interventions should involve a high capability of theinvolved population to continue to use new products, techniques and systems in continuouslychanging circumstances. Thus, in reality, technological capabilities rather than technologicaloptions must be the focus of attention

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Tables

PN Station Latitude Longitude

1 Abu Dhabi 24.35 -54.58

2 Aden 11.36 -43.093 Alexandria (Nouzha) 31.12 -29.57

4 Bagdad 33.14 -44.31

5 Baku 40.20 -49.41

6 Bamaco 12.45 7.48

7 Bangui 4.24 -18.31

8 Basrah 29.13 -47.59

9 Belem -1.28 48.27

10 Belo Horizonte -19.56 43.56

11 Brazzaville -4.15 -15.14

12 Cairo 30.05 -31.17

13 Casablanca 33.34 7.40

14 Dakar 14.48 17.01

15 Damascus (Kharabo) 33.3 -36.28

16 Khartoom 15.36 -32.33

17 Mogadiscio 1.58 -45.26

18 Monrovia 6.32 10.36

19 Muscat 23.25 -58.48

20 Ndjamena (Fort Lamy) 12.08 -15.02

21 Paramaribo 5.58 55.2722 Port Soudan 19.35 -37.13

23 Pretoria -25.45 -28.14

24 Rabat 33.51 6.40

25 Sanaa 15.18 -44.29

26 Sao Paulo -23.3 46.37

27 Tabriz 37.52 -46.08

28 Teheran 35.41 -51.12

29 Walvis Bay -23.08 -14.42

Table 1. The places where simu lations have been performed.


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Cooling load (kWh/m2)SN Station

conventional high refl.Roof

difference(B A)

Percentage(B A) / A

1 Abu Dhabi 265.4 212.0 -53.4 -20.1%2 Aden 287.1 222.3 -64.9 -22.6%

3 Alexandria (Nouzha) 69.4 34.5 -34.9 -50.3%

4 Bagdad 142.3 105.3 -37.0 -26.0%

5 Baku 44.4 23.6 -20.9 -46.9%

6 Bamaco 211.5 145.4 -66.1 -31.3%

7 Bangui 141.9 87.3 -54.6 -38.5%

8 Basrah 193.5 151.8 -41.8 -21.6%

9 Belem 146.0 92.4 -53.6 -36.7%

10 Belo Horizonte 26.1 6.1 -20.0 -76.7%

11 Brazzaville 117.0 69.1 -47.9 -40.9%

12 Cairo 106.2 63.0 -43.2 -40.7%

13 Casablanca 30.4 8.7 -21.6 -71.2%

14 Dakar 122.6 62.8 -59.7 -48.7%

15 Damascus (Kharabo) 65.3 32.7 -32.6 -49.9%

16 Khartoom 285.3 212.8 -72.5 -25.4%

17 Mogadiscio 256.5 194.8 -61.8 -24.1%

18 Monrovia 160.0 103.5 -56.6 -35.3%

19 Muscat 198.4 145.8 -52.6 -26.5%

20 Ndjamena (Fort Lamy) 258.4 187.9 -70.5 -27.3%

21 Paramaribo 148.3 94.0 -54.3 -36.6%

22 Port Soudan 263.6 198.0 -65.6 -24.9%

23 Pretoria 24.0 4.9 -19.1 -79.5%

24 Rabat 29.4 9.5 -19.9 -67.7%

25 Sanaa 26.8 7.6 -19.2 -71.7%

26 Sao Paulo 6.1 0.8 -5.3 -86.2%

27 Tabriz 34.7 15.8 -18.8 -54.4%

28 Teheran 85.3 54.8 -30.5 -35.7%

29 Walvis Bay 256.6 190.5 -66.1 -25.8%

Table 2. The calculated cooling load for both scenarios and the expected energy savings.


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Table 3. Reduction of the hours with indoor temperature above 30, 27.5 and 26 C, for theconventional and the building with the reflective roof

Hours Above the following Indoor Temperature

30C 27.5C 26C

SN Place

Conventional

ReflectiveRoof

Reductionof

discomforthours

Conventional

ReflectiveRoof

Reductionof

discomforthours

Conventional

ReflectiveRoof

Reduction ofdiscomfort hours

1 Abu Dhabi 5987 5349 10,7% 6968 6255 10,2% 7516 6849 8,9%

2 Aden 7818 6778 13,3% 8521 8006 6,0% 8661 8456 2,4%

3Alexandria(Nouzha) 1996 691 65,4% 3295 1970 40,2% 4003 2789 30,3%

4 Bagdad 3467 2822 18,6% 4041 3544 12,3% 4384 3913 10,7%

5 Baku 1222 513 58,0% 2061 1275 38,1% 2540 1829 28,0%

6 Bamaco 6452 4310 33,2% 8058 6952 13,7% 8496 7935 6,6%

7 Bangui 4393 1575 64,1% 7594 5561 26,8% 8373 7513 10,3%

8 Basrah 4251 3765 11,4% 4906 4407 10,2% 5221 4832 7,5%

9 Belem 4536 2022 55,4% 7287 5412 25,7% 8230 7303 11,3%

10 Belo Horizonte 196 0 100,0% 1342 245 81,7% 2776 923 66,8%

11 Brazzaville 3314 1037 68,7% 6450 4414 31,6% 7602 6497 14,5%

12 Cairo 3190 1688 47,1% 4279 3207 25,1% 4753 3979 16,3%

13 Casablanca 462 34 92,6% 1501 402 73,2% 2362 996 57,8%

14 Dakar 3210 764 76,2% 6487 3603 44,5% 7749 5744 25,9%

15Damascus(Kharabo) 1847 740 59,9% 2735 1743 36,3% 3218 2296 28,7%

16 Khartoom 7228 6167 14,7% 8089 7308 9,7% 8467 7885 6,9%

17 Mogadiscio 8201 6981 14,9% 8732 8623 1,2% 8750 8747 0,0%

18 Monrovia 5312 2816 47,0% 7666 6271 18,2% 8267 7655 7,4%19 Muscat 5583 4617 17,3% 6749 5896 12,6% 7460 6653 10,8%

20Ndjamena (FortLamy) 7269 5822 19,9% 8214 7454 9,3% 8539 8049 5,7%

21 Paramaribo 4724 2429 48,6% 7228 5569 23,0% 8232 7312 11,2%

22 Port Soudan 6769 5592 17,4% 7883 6956 11,8% 8340 7704 7,6%

23 Pretoria 239 6 97,5% 1162 176 84,9% 2060 620 69,9%

24 Rabat 518 25 95,2% 1511 431 71,5% 2299 1035 55,0%

25 Sanaa 327 7 97,9% 1474 343 76,7% 2469 1012 59,0%

26 Sao Paulo 19 0 100,0% 280 24 91,4% 733 140 80,9%

27 Tabriz 874 239 72,7% 1670 881 47,2% 2173 1354 37,7%

28 Teheran 2417 1638 32,2% 3071 2453 20,1% 3388 2843 16,1%


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Table 4. Maximum calculated indoor temperatures for the conventional and the building withthe reflective roof.

.

Temperatures (C)SN Place

Conventional High refl.paint

difference(B A)

Percentage(B A) / A

1 Abu Dhabi 46.8 44.1 -2.7 -5.7%

2 Aden 46.3 43.4 -2.9 -6.2%

3 Alexandria (Nouzha) 38.1 35.1 -3.1 -8.0%

4 Bagdad 45.6 42.4 -3.2 -7.0%

5 Baku 37.4 34.2 -3.1 -8.4%

6 Bamaco 40.4 37.7 -2.7 -6.7%

7 Bangui 36.1 33.5 -2.6 -7.3%

8 Basrah 47.0 43.7 -3.3 -7.0%

9 Belem 39.0 36.8 -2.2 -5.7%

10 Belo Horizonte 32.6 29.9 -2.7 -8.3%

11 Brazzaville 36.3 33.3 -3.1 -8.5%

12 Cairo 39.4 36.1 -3.3 -8.5%

13 Casablanca 35.2 31.9 -3.3 -9.3%

14 Dakar 37.6 35.0 -2.6 -6.9%

15 Damascus (Kharabo) 37.7 34.1 -3.7 -9.7%

16 Khartoom 44.2 41.1 -3.1 -7.0%

17 Mogadiscio 41.3 38.8 -2.5 -6.0%

18 Monrovia 39.1 36.2 -2.9 -7.3%

19 Muscat 43.4 40.6 -2.8 -6.5%

20 Ndjamena (Fort Lamy) 42.9 40.0 -3.0 -6.9%21 Paramaribo 39.4 36.6 -2.8 -7.2%

22 Port Soudan 45.2 42.7 -2.5 -5.5%

23 Pretoria 34.1 31.2 -2.9 -8.6%

24 Rabat 34.2 31.3 -2.9 -8.4%

25 Sanaa 33.4 30.7 -2.7 -8.1%

26 Sao Paulo 31.0 28.6 -2.4 -7.8%

27 Tabriz 36.1 32.7 -3.4 -9.5%

28 Teheran 41.9 38.6 -3.3 -7.8%

29 Walvis Bay 47.0 43.8 -3.2 -6.8%


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Figures

Figure 1. Cumulative Frequency Distribution of the cooling load for the conventional and for thebuilding with the reflecting roof.

0 50 100 150 200 250 3000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Cooling Load (kWh/m2/y)

F(x)

ConventionalBuilding

BuildingWith Reflective Roof

0 50 100 150 200 250 3000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Cooling Load (kWh/m2/y)

F(x)




19/22



Figure 2. Cumulative Frequency Distribution of the hours with indoor temperature above 30,27.5 and 26 C, for the conventional and the building with the reflective roof.


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Figure 3. Cumulative Frequency Distribution of the maximum calculated indoor temperaturesfor the conventional and the building for the building with the reflecting roof.

28 30 32 34 36 38 40 42 44 46 480

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

F(x)

Max Indoor Temperature (C)



28 30 32 34 36 38 40 42 44 46 480

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

F(x)

Max Indoor Temperature (C)




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Figure 4: Estimated Indoor TVOCs Concentrations (mgr/m3) Considering Two Indoor TVOCsEmission Factors For 5 Canyon Configurations For a) Natural and b) Hybrid VentilationExhaust systems, For Athens Reference Year

0

5

10

15

20

1 2 3 4 5 1 2 3 4 5

TVOC's(m

gr/m

3)

1.1 mgh-1

m-2

2.2 mgh-1

m-2

a0

5

10

15

20

1 2 3 4 5 1 2 3 4 5

TVOC's(m

gr/m

3)

1.1 mgh-1

m-2

2.2 mgh-1

m-2

b


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Figure 5: Estimated % Of Hours, When Indoor Air Quality Is Perceived With Different ControlStrategies With Natural And Hybrid Ventilation Exhaust Systems, For Athens Reference Year

0

20

40

60

80

100

Percentageofhours(%)

Natural Hybrid

CO2 TVOC'sCO2&

TVOC's

Passive

Cooling

&TVOC's

Passive

Cooling

&CO2

Passive

Cooling

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