Category Archives: EuroSun2008-4

Solar air conditioning of office rooms, seminar rooms and server room

Due to the high electrical coefficient of performance of conventional compression chillers, the primary energy consumption is despite the use of electricity still reasonable. In order to save primary energy with replacing these systems with a solar thermal driven air conditioning system and a thermal back-up system using fossil fuels, high solar fractions and high coefficients of performance of the cold production are necessary. The coefficient of performance depends mainly on the chiller technology and on the temperatures in the heating, cooling and re-cooling circuits.

For temperatures delivered by typical solar collectors and for typical absorption chillers, this value does not vary much and is in the range of 0.6-0.8. Based on such a thermal coefficient of performance and compared to typical compression chillers with electrical coefficients of performance of about 3.5, only solar air conditioning systems with solar fractions of more than 60% are leading to primary energy savings [2].

However, the solar fraction of a solar air conditioning system depends on many factors of which the most important are:

■ Time dependent matching of available heat from the solar thermal system and cooling demand

■ size of the solar collector field

■ efficiency of all system components

■ storage capacity

■ control strategy

For the reference case in the simulation studies, a flat plate collector field with an area of 150 m2, which would be appropriate for typical solar air conditioning applications using absorption chillers with a cooling capacity of 50 kW, and a hot water store volume of about 16 m3 was chosen. With this configuration, a significant contribution of the solar thermal system to the cold production was determined. However, the solar fraction for cooling of the office rooms, seminar rooms and the server room determined for the the building described was less than 50 %. Regarding this, Fig. 5 shows the back-up heater operation depending on ambient temperature and actual irradiation for a period in August. It can be seen that back-up heating is mainly required during times of high ambient temperatures but comparable low irradiance.

Подпись: 1st International Congress on Heating, Cooling, and Buildings " ' 7th to 10th October, Lisbon - Portugal * її • 11 ■ Ie ■ |И и 11 |И 19.Aug 20.Aug 21.Aug 22.Aug 23.Aug 24.Aug 25.Aug Fig. 5: Time of back-up heating depending on ambient temperature and global radiation.

Thus, it can be expected that a change in the system configuration of the solar thermal system can increase the solar fraction. Regarding this, three different approaches have been investigated:

a) Collector area:

Increasing the collector has a significant effect on the solar fraction. It could be shown that doubling the collector area can increase the solar fraction up to 70 %

b) Collector type:

Changing the collector type to 150 m2 vacuum tube collectors can increase the solar fraction up to 75 %

c) Storage volume:

Doubling the storage tank volume can increase the solar fraction only up to around 65 %

Based on these investigations, it could be shown that with an adjusted system design, high solar fractions for cooling are possible. However, all these adjustments are leading to high investments. Due to this, alternative concepts need to be investigated. Some of these are discussed as follows:

Alternative storage concepts

Because of the small temperature step of supply and return flows during the operating of absorption chillers, the effective storage capacity of water tanks is limited, especially since temperatures of more than 80°C are required to drive the chillers. Thus, due to a high storage density at small temperature steps, a replacement of water storage tanks by storage tanks using phase change materials seems to be promising. Herewith, a reduction of the storage volume of down to 1/5 seems possible.

Alternative cooling technologies

Since mostly summer days with low radiation are responsible for the relatively low solar fraction, alternative solar cooling technologies which require lower driving temperatures could overcome

this problem. Since server rooms are usually cooled with ventilated air, open cycle systems using liquid dessicants, e. g. [7], can lead to efficient system designs. These systems require temperatures of only 60-70°C, which can be supplied even on days with lower radiation.

Different server room temperatures

One approach to further decrease the energy demand for cooling of server rooms is the increase of the room temperature in the server room itself. Investigations in [8] on the tolerable temperature of data processing equipment are recommending temperatures of up to 26°C. With such an increase, the proportion of free cooling would be, especially for Germany, increased by a large extend. However, the solar fraction of the remaining cooling demand would not necessarily increase, too.

Integrated system for heating and cooling

To increase the overall efficiency of the system for heating and cooling, the use of waste heat from the server room for heating the building in winter times should be applied. For this, the amount of energy reduction depends on the efficiency of the ventilation strategy and its heat recovery system as well as on the temperature in the server room. In addition, heating can be supplied by the solar thermal system at times when the energy is not used for the cooling process. In that case, the yearly gain of the collector field would be increased. However, the amount of primary energy reduction depends on the building design, too.

Bivalent cooling strategy

If the solar fraction cannot be increased with one of the measures mentioned above, a bivalent cooling strategy would still lead to significant primary energy reductions. In that case, both thermal driven chillers and vapour compression chillers would be used for the cooling of the building and the server room. As long as thermal energy would be available from the solar thermal system, the thermal chiller would supply the cold. As back-up during times of low radiation, the conventional electrical chiller would be operated. A draw-back of this approach is that the investment would increase due to the requirement of two different cooling technologies. Furthermore, the complexity of the design and operation of the system itself would increase, too. However, both issues would be eliminated if an emergency back-up system would be required anyway and if such a system could be used as a normal operational back-up, too.

3. Conclusion

In the present paper, investigations on using solar thermal energy to cool a passive office building with seminar rooms, office rooms and especially a server room are presented. It could be shown that even if the cooling demand for the seminar and office rooms of the investigated building is quite small, the peak cooling load can be significant even if appropriate shading devices are used. Due to the good coincidence of solar radiation and cooling demand, solar air conditioning systems can lead to significant improvements of the user comfort. Due to the relatively constant cooling demand of a server room, special measures have to be implemented in order to use the solar thermal systems to cool the server room, too. It was shown that the use of ambient air during cold or mild periods can reduce the cooling demand of the server room by almost a factor of 3. Thus, ambient cold represents the most efficient way to reduce the energy demand for cooling of server rooms. In addition, it was shown that with this reduced cooling demand, which almost matches the solar radiation available, the use of solar air conditioning system can reduce the primary energy demand for cooling even more. However, for a significant primary energy reduction compared to the use of conventional compression chillers, high solar fractions are necessary. Thus, for a special

application, it needs to be proven whether additional measures like the use of compression chillers as back-up, or the use of the solar thermal system and the server waste heat for heating the building during winter time, can be applied.

5. Acknowledgment

The authors wish to thank the company Wagner& Co Solartechnik for supporting the investigations presented in this paper.

References

[1] European Commission, (2007). Green Paper — Adapting to climate change in Europe — options for EU action, Brussels

[2] Henning H.-M., (2004). Solar-Assisted Air-Conditioning in Building — A Handbook for Planners. Springer-Verlag Wien

[3] Mines Paris ParisTech — Center for Energy and Processes, (2008). High efficiency and low environmental impact air-conditioning systems Air-conditioning key figures in the world, in Europe and in France, http://www. cenerg. ensmp. fr/english/themes/syst/index. html.

[4] EnergieAgentur. NRW (2008). Ohne Energie keine Information — Rationelle Energieverwendung in Rechenzentren und EDV-Raumen. Wuppertal.

[5] Afonso, C. F.A. (2006). Recent advances in building air conditioning systems, Applied Thermal Engineering, Vol 26.

[6] H.-M. Hellmann, C. Schweigler, F. Ziegler, (1999). The characteristic equation of sorption chillers. Proc. Int. Sorption Heat Pump Conf., Munich, 24.-26. March 1999; pp. 169-172.

[7] Lavemann, E., Peltzer, M. (2003): Solar Liquid Desiccant cooling System Demonstration Plant, ISES Solar World Congress, Goeteborg, 14.-19.6.2003.

[8] American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) (2003). Thermal Guidelines for Data Center and Other Data Processing Environments. Atlanta, U. S..

Function as a solar collector

Подпись:
First of all, the collector can be regarded as a fa? ade collector with its typical advantages, disadvantages and special aspects to be considered in order to be designed properly. One of these important aspects is the minimum backside insulation [3, 4] to prevent the room from overheating. In the case of the semi-transparent collector these minimum insulation requirements have to be fulfilled by the inner glass pane(s). Depending on the efficiency of the collector and thus its temperature level, it will be necessary to use a double glazing with Low-E coating as “backside insulation” or multi­layers of transparent foils [7]. Another important topic will be the effect of the openings and the position of the absorber on the natural convection within the collector and thus on its efficiency. In order to have a high flexibility concerning the absorber channel design as well as an aesthetic appearance, roll-bond absorbers (Fig. 4) seem to be a good choice for this type of collector. In conventional absorbers, the heat transfer direction from the absorber surface to the next channel is basically perpendicular to the channel direction. In the case of an absorber with a three-dimensional structure it has to be considered that the heat transfer distance to the fluid is increased and the cross section is reduced: The sides of the lamellae (bent to outside) are not in contact with the channel; therefore the heat transfer is only possible via the remaining flat areas of the absorber which are connected to the channels. The advantage of roll-bond absorbers is the fact that their channel distance can be reduced without additional costs. It can be expected that smaller channel distances will compensate for the lower heat transfer of the three-dimensional structure mentioned above and thus lead to high collector efficiency factors F’ anyway. Moreover, for large sun elevation angles the incidence angle modifier (IAM) of the lamellae should be higher than for a flat vertical absorber. This could be beneficial for solar gains in summer in order to drive a solar cooling system. Roll-bond technology also offers the possibility to realize optimized channel arrangements such as fractal-like, multiply branched FracTherm® structures which lead to a low pressure drop as well as a uniform flow distribution [5, 6]. Even non-rectangular shapes can be used, which might be interesting for architectural reasons.

Regarded as a window-like building component, the three-dimensional structure of the absorber leads to an angular-selective behaviour. Depending on the geometry of the openings and their coating the properties concerning absorption, transparency, daylighting, solar control and glare protection can be adjusted according to the specifications of the particular application. Fig. 5 shows some principal variations of geometry and coating. Variant a) mainly focuses on absorption, transparency, solar control and glare protection, but it will have a poor performance with respect to daylighting since there are no reflecting surfaces leading the sunlight to the inside. In contrast to a), the diffuse reflector of

image441

Variant b) features better daylighting behaviour, but poor absorption, solar control and glare protection. Variants c) and d) can be regarded as compromises of a) and b) with different focuses.

image442

image443

In Fig. 6 different views of a detail of a possible semi-transparent absorber with lamellae and fluid channel are shown. The size of this small part is only about 128 mm x 150 mm. The exterior view in a) gives an impression of the absorber seen from outside, whereas the internal view in b) shows the appearance from inside. It can be seen that for the assumed sun elevation angle a homogeneous shadow is formed (without light stripes from the openings). View c) and d) show how the effective transparency changes with the angle: only small slits appear if one looks through the absorber horizontally, but they seem to become bigger if one looks downwards. This effect is especially interesting for multi-storey buildings.

Fig. 7 shows the absorber detail at different incidence angles of the sun. In the raytracing simulations the absorber was oriented towards south and the solar azimuth angle was always 0. It can be seen that even for small incidence angles the shadow is homogeneous.

Fig. 8 gives an impression of the appearance of an absorber with an area of 1 m x 2 m and its shadow. In this case parallel, vertically oriented channels were assumed. However, other channel designs are also possible.

The typical room

The typical room used for the studies is a standard cross ventilated classroom, 7 x 7 x 2.7 m. The external concrete wall are 16cm thick with three windows for each facades (see Figure 3). Different values of porosity (percentage of openings with regard to the facade) to quantify the

impact on the autonomy in natural lighting. Two azimuths have been considered for the main facades : North and South then East and West

Only a overhang solar shading type has been considered. The TMY weather file used is the one from Saint Pierre, a town located in the south of La Reunion.

The classroom has been divided into three equal strips. The daylight factor and the illuminance level have been calculated for each strip.

image469

Heating and Cooling Degree-Day’s distribution on Mendoza’s Metropolitan Area

The differences between the values of HDD and CDD obtained from the different of measurement sites (urban and rural stations within MMA and the local weather station at the airport) were calculated. These differences were expressed as percentages in order to quantify the error’s magnitude incurred in the calculation of the studied variables when not considering the effect of the city on the local climate.

Table 3. Monthly values of HDD y CDD corresponding to the north transect. Stations 50 vs. 59 and the

Airport’s station are compared. (See figure 1)

Urban Area

Rural Area

Airport

Difference %

CDD

HDD

CDD

HDD

CDD

HDD

U-R

U-A

R-A

January

247

212

226

17%

9%

-6%

February

191

143

178

34%

7%

-20%

March

82

49

76

68%

9%

-35%

April

50

127

100

-61%

-50%

27%

May

142

235

183

-40%

-22%

28%

June

178

310

267

-43%

-33%

15%

July

225

331

282

-32%

-20%

17%

August

200

279

248

-28%

-19%

12%

September

80

178

162

-55%

-50%

10%

October

54

26

0

107%

November

185

146

174

26%

6%

-15%

December

315

228

220

38%

43%

4%

Table 4. Monthly values of HDD y CDD corresponding to the south transect. Stations 50 vs. 40 and the

Airport’s station are compared. (See figure 1)

Urban Area

Rural Area

Airport

Difference %

CDD

HDD

CDD

HDD

CDD

HDD

U-R

U-A

R-A

January

247

180

226

37%

9%

-20%

February

191

127

178

50%

7%

-28%

March

82

40

76

86%

9%

-41%

April

50

131

100

-62%

-50%

31%

May

142

243

183

-42%

-22%

32%

June

178

236

267

-25%

-31%

8%

July

225

337

282

-41%

-20%

17%

August

200

291

248

-39%

-19%

17%

September

80

122

162

-34%

-50%

25%

October

54

23

0

134%

November

185

146

174

27%

6%

-16%

December

315

217

220

45%

43%

-1.5%

Table 5. Monthly values of HDD y CDD corresponding to the west transect. Stations 50 vs. 3 and the

Airport’s station are compared. (See figure 1)

Urban Area

Rural Area

Airport

Difference %

CDD

HDD

CDD

HDD

CDD

HDD

U-R

U-A

R-A

January

247

176

226

40%

9%

-22%

February

191

132

178

44%

7%

-26%

March

82

52

76

60%

9%

-31%

April

50

94

100

-47%

-50%

6%

May

142

219

183

-35%

-22%

19%

June

178

287

267

-38%

-33%

7%

July

225

301

282

-25%

-20%

6%

August

200

290

248

-31%

-19%

17%

1st International Congress on Heating, Cooling, and Buildings, 7th to 10th October, Lisbon — Portugal /

September

80

120

162

-33%

-50%

-26%

October

54

23

0

134%

November

185

142

174

30%

6%

-18%

December

315

195

220

61%

43%

-11%

Table 6. Monthly values of HDD y CDD corresponding to the east transect. Stations 50 vs. 15 and the

Airport’s station are compared. (See figure 1)

Urban Area

Rural Area

Airport

Difference %

CDD

HDD

CDD

HDD

CDD

HDD

U-R

U-A

R-A

January

247

217

226

14%

9%

-4%

February

191

170

178

12%

7%

-4%

March

82

60

76

37%

9%

-20%

April

50

89

100

-44%

-50%

11%

May

142

201

183

-29%

-22%

9%

June

178

263

267

-32%

-33%

2%

July

225

279

282

-19%

-20%

-1%

August

200

259

248

-23%

-19%

4%

September

80

96

162

-17%

-50%

-40%

October

54

23

0

134%

November

185

147

174

26%

6%

-15%

December

315

164

220

92%

43%

-25%

The results show that during summer time there exists an underestimation in the cooling demand calculated from the data obtained by local weather stations that oscillates between 6% and 43%. For the winter time, it happens oppositely, an overestimation of the heating load that represents an error from about 19% to 50%.

In the case of the air temperature behavior in downtown respect to its surroundings, it is observed that the demand for cooling in the downtown area is higher than 12% and up to a 130% respect to the surroundings demands, depending on the month of a year and the zone of the city analyzed.

The demand of heating for downtown area respect to the environs is smaller in the order of 25 to 62%.The energy requirements of the suburban and rural zones of the city respect to the values calculated from the local weather station show an overestimation of 4% to 41% of the cooling necessities, and an underestimation of 2% to 32% in the case of the heating demand.

Figure 3 shows the yearly distribution of HDD and CDD within the AMM. The degree day’s distribution responds clearly to the thermal behavior and to the climatic conditions that prevail in the city. During the summer the radiation levels are high, for this reason the materials that compose the ground of the city’s out-skirts, which are mainly rocky, accumulate heat during the day, homogenizing the distribution of temperatures between downtown area and the city’s out-skirts of the. This does not happen in winter due to the lesser amount of radiation during the day, increasing the temperature differences between downtown and the rural areas.

The greater demand in refrigeration during the month of December can be explained by the increase of the anthropogenic contribution in the city, because this is a festive month, whereas January and February are months of vacations. The maps that show the distribution of heating and cooling degrees-day within the AMM always display a hot zone of greater demand of refrigeration and minor demand of heating coincident with the administrative-commercial zone in the city.

PV system payback analysis

The financial analysis combines the impact of different system implementation costs (400€/m2 and 600€/m2) and sale prices of PV electricity to the grid, in a total of eight scenarios:

• 0.08€/kWh: the typical average cost of electricity bought to the grid

• 0.20€/kWh: an estimate of the corrected value of electricity bought to the grid, taking in account the rise of the oil barrel prices in the last years

• 0.40€/kWh: the typical value of renewable PV generated electricity sold to the grid in Portugal

If all PV produced electricity is sold to the grid, the simple payback periods of the PV systems are:
Figure 7 — Payback of the PV system if all electricity produced by the schools is sold to the grid

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Alternatively part of the PV generated electricity may be used in the school, leading to different payback periods. Considering that all the electricity produced during the week days will be consumed in the school (a saving of 0.08 €/kWh on the electricity bill of the schools, 45% of the days in a year), and that for the reminder of the days, including weekends and holidays (55% days of the year) the electricity produced is sold to the grid at the three prices previous addressed, a new payback periods is obtained (see figure 8).

Figure 8- Payback of the PV system if part of the electricity produced, 45% days of the year, is used in the

school (the rest will be sold).

image367

3. Conclusion

This study determined the following average values for the implementation of PV system in Portuguese high schools:

Table 2 — Summary table for this study

School Type

РУ Area m2

PV Capacity kW

Cost k€

Cost Є/m2 of floor area

Electrical demand reduction %

Energy

Class

P

1000

140

500

62

50

A, A+

NP

480

60

240

26

20

B, A

The total PV potential of the 172 schools is approximately 144 000m2 with a capacity of generation of 25GWh/year.

The implementation of this systems is more favorable for pavilion schools due to their higher PV to floor area ratio and easier installation and maintenance of panels (flat accessible roofs).

The electrical energy autonomy values obtained, based on the energy consumption for a typical school do not consider the effect of additional optimization measures (lighting, natural ventilation etc.). It can be expected that, for the best cases, after those optimization measures, to achieve values of autonomy close to 100% (on a net yearly base).

If the electricity produced is sold to the grid at a realistic price, unsubsidized price of 0.20€/kWh, the simple payback varies between 11 and 17 years, for both scenarios considered. The payback varies notably with the cost of PV per square meter and with the PV electricity sale price to grid.

References

[1] Study for Parque Escolar: Avaliagao do Potencial Solar Fotovoltaico, NaturalWorks,

2008.

[2] Decreto-Lei 80/2006, de 4 de Abril, Regulamento das Caracteristicas de Comportamento Termico dos Edificios (RCCTE)

[3] Decreto-Lei79/2006, Regulamento dos Sistemas Energeticos de Climatizaqao em Edificios (RSECE)

[4] Decreto-lei n° 78/2006 de 4 de Abril aprova o Sistema Nacional de Certificaqao Energetica e da Qualidade do Ar Interior nos Edificios (SCE)

[5] European Union directive 2002/91/CE

[6] Solterm Software, INETI, Portugal

[7] Portuguese Energy Agency (ADENE): http://www. adene. pt/

[8] International Energy Agency, Portugal, Energy Balance, 2005.

PV Park system results

Подпись: Month Fig. 5. PV park system - Monthly average of the daily energy produced, per installed peak power.
Fig. 5 presents the values of the monthly averages of the daily energy produced in the park, per installed peak power. This system produces more energy in summer periods with a maximum average daily production of 34.8 kWh at July 2006 and July 2007. The production minimum occurred at December 2007 with a daily average production of 11.1 kWh.

At Table 4 we present the yearly irradiation and energy produced by PV Park system. The yearly irradiation measured, in the 15° tilted surface, is about 1 790 kW/m2 each year and the energy production is about 1 400 kWh per kW of peak power installed. The low production in 2006 year, despite the bigger irradiation, is due to an inverter failure during two weeks in the month of May.

Table 4. Yearly energy produced by PV park system, per installed peak power

Year

Power

Irradiation

Production

(kW)

(kWh/m2)

(kWh/kW)

2006

6.00

1 799

1 366

2007

6.00

1 781

1 407

This results show that the energy production by installed peak power of the facade system is about

28.6 % lower than for the park system, this is due mainly to the lower incident irradiation on the facade surface.

Phase change materials

Systems that use Phase Change Materials (PCM) can be used to store energy. All substances store energy when their temperature changes, but when a phase change occurs in a substance, the energy stored is higher. Furthermore, heat storage and recovery occur isothermally, which makes them ideal for space heating /cooling applications.

3.8 Colour of exterior surfaces

A light colour of surfaces is an effective solution to reduce unwanted solar gains. The quantity of radiation that is absorbed by a surface depends on its colour. Light colours are effective in reducing cooling loads, whereas dark ones are more appropriate to absorb heat in thermal storage.

3. The Portuguese Passivhaus proposal

This section presents a prototype Passivhaus proposal for Portugal. Detailed results from parametric analysis as well as the other partner’s proposals for the UK, Spain, Italy and France are available in the technical guidelines produced in the project. [6]

3.1 Concept

Подпись: Fig. 1. Prototype of the Passivhaus in Portugal.

The Portuguese Passivhaus proposal is a two-bedroom house which complies with the national building thermal regulation 2006 (RCCTE, DL 80/2006). The prototype avoids imposing a specific layout allowing the architects the freedom of design. The strategies applicable to the Passivehaus proposal were adapted to the Portuguese context, in particular those regarding the cooling season. Special care was taken to adopt commonly-used building practices to avoid an increase of the overall cost and to ease the procurement and its implementation. The current proposal, with a total useful area of 110 m2, takes into account the local climate (case study for Lisbon). It relies initially on passive strategies complemented with simple active systems, if required. Three main aspects are explored in the proposed house: relation with the sun, ventilation for cooling and high thermal mass to control temperature swings.

Building Description

A typical small 3-storey office with a total floor area of 4200m2 was modelled in the Energy Efficiency Measure module of RETScreen [14] with the TMY weather data used in the TRNSYS simulations. This software is meant for pre-feasibility studies, but it was used in this case to easily compare the building space heating and cooling energy requirements of the different scenarios and avoid the complexity of multi-zone building simulation tools. The building lighting, equipment and appliances load, occupant density, natural air infiltration, ventilation rates and schedules were set to typical values for small office buildings [15]. The windows on all the non south-facing facades

were assumed to be fixed, low-e, triple-glazed and to have an overall U-value and SHGC of 1.57 W/m2oC and 0.27, respectively. The percentage of fenestration was set to 20% on the north wall and 40% on the east and west facades. The other building envelope properties for each city were selected to fulfil the minimum requirements of the Model National Energy Code for buildings (MNECB) [16] with oil selected as the principal heating source for Iqaluit and Yellowknife. The substitution of spandrel panels with multi-glazing BIPV systems was considered to have negligible effect on the lighting load.

User oriented energy assessment of classified facade systems

Подпись: Fig. 2. Comparison of three differents facades in terms of primary energy

A user of the evaluation system can find the stored energy data of any fa? ade system he is interested in by an EXCEL tool. Figure 2 shows an example with the the comparison of three different fa? ade systems in terms of primary energy for heating, cooling, ventilation, and lighting.

By the comparison of different facade systems the energetic advantages and disadvantages of morphological variations of the facades can be found easily. In order to combine the evaluation aspect of primary energy with other aspects, like e. g. embodied energy, in an overalll evaluation, the

Подпись:
transformation of energetical data into marks can be helpful. Another way of cumulation are life-cycle balances. Figure 3 shows an example for the comparison of three fa? ade systems in terms of grades / marks on a scale from 1 (low grading) and 5 (high grading). The evaluation system offers a special EXCEL tool for calculating the embodied energy, based on tables with specific values for the most common building materials.

Hourly thermal simulation

The hourly building thermal behaviour was simulated with the soft SIMEDIF for Windows, a code developed at INENCO and widely used in Argentina [3, 4]. SIMEDIF needs the building to be divided into thermal zones, that are represented by an air node with a single temperature, whose temporal evolution is determined by using the building data, materials, location, orientation, connections with other zones and climatic conditions. The zones can be connected to each other and with the outdoors by pre-defined elements, that can store and transfer heat by conduction and convection (radiation is linearized). An energy balance is performed at each node for which the temperature is to be determined. In this global balance equation, the air renewals in the room, inner

image421

heat gains, and heat transfer due to the different elements connecting the room with other zones in the building and with outdoors, are considered. More details can be found in [3].

Подпись: Fig. 3. Thermal zoning of Health and Development Sectors.

The thermal zones for Development and Health Sectors are shown in Fig. 3. The Health Sector was divided in eight thermal zones (access, South corridor, North corridor, doctors offices 1 to 3, bathrooms, doctors offices 4 and 5, laboratory and meeting room) and the Development Sector in six thermal zones (kindergarten, services, corridor, deposit, social assistant office, and classrooms). The building was simulated under a non occupancy schedule, for typical winter and summer days.

The meteorological data were obtained from Table 1 and the hourly temperature and solar irradiance was automatically calculated by SIMEDIF from mean daily values. The solar absortances were fixed in 0.3 for external wall surfaces (light colour painting) and 0.7 for external roof surfaces (dark red painting).