Category EuroSun2008-4

Contribution of Solar Thermal Systems to building energy. performance – comparison of Portuguese methodology with European

Standard EN 15316 (part 4-3)

Maria Joao Carvalho ^ and Ana Neves 1

1 INETI, Department of Renewable Energies, Campus do Lumiar do INETI, 1649-038 Lisbon, Portugal
* Corresponding Author, mioao. carvalho@ineti. pt


In the frame of European Directive for Energy Performance in Buildings, EU Directive 2002/91/CE, Portugal produced legislation transposing the EU Directive and imposing the usage of thermal solar systems for hot water preparation. The energy necessary for the preparation of hot water constitutes one of the terms for evaluation of energy performance of the building. The calculation methodology is incorporated in a software tool developed by INETI and called SolTerm...

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Advantages of the collector and possible applications

The described semi-transparent collector is a multifunctional architectural design element. This offers a new market potential for solar thermal energy use. At a certain distance the structure of the small openings appears as a homogeneous semi-transparent area with the silhouette of the channels. This offers interesting possibilities in design: straight vertical or horizontal channel arrangements as well as curved designs such as in a FracTherm® absorber [5] can be realized if roll-bonding or another production method with similar flexibility is used.

Подпись: Fig. 9: Semi-transparent absorber integrated into a balcony balustrade

Office buildings often feature large glazed fa? ade areas and need appropriate devices for solar control and glare protection. Moreover, cooling becomes more and more important...

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Calculation assumptions

The reflectivity of walls, ground and ceiling are respectively 0.75, 0.45 and 0.75.

The Lighting French Association recommands an illuminance level of 300 lux in a typical office

[4] . In this study, the value of acceptable illuminance level has been set to 300 lux. To quantify the mean daylight autonomy in the room, the room has been divided into three equal strips (see Figure 3). The illuminance level is supposed to be the worst in the middle strip. For this reason, we will focus on this specific zone.

3. Results and discussion

This section presents some preliminary results of the study to determine a combination between the solar shading and daylighting in buildings.

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Global Warming Impact

The results presented in the figure 3 support the idea that if we consider that all building design variables (orientation, materials, SOF, TOF, technology, etc) are maintained constant and only the location of buildings in the city are modify; the emissions related to the energy consumption vary

Подпись: Figure 2. (a) CDD yearly distribution 2005. (b) HDD yearly distribution 2005.

significantly too. It is especially during winter’s month. During winter the heat island effect results in minor energy consumption and, in consequence decreases the emissions generation. This could be thought as a beneficial effect, but it is important remember, that associated with this phenomena there are other environmental problems, as it was explained in the introduction.

4. Conclusions

Until now, in the study area, the values of HDD and CDD calculated for the bioclimatic zoning no...

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Fenestration-Shading, The Human Factor And Energy Efficient Buildings

Despina K. Serghides

Architect/Department of Civil Engineering, School of Engineering & Technology
Cyprus University of Technology
Tel: 357-25002542, 25002724, Fax: 357-25002769,

Email: D. K.Serghides@cytanet. com. cy

In previous research on energy efficiency in buildings has found that it is possible to achieve comfort conditions, for the Mediterranean climate, without the need for mechanical energy for heating and cooling in houses, through the use of compact shape and the optimization of insulation, internal mass and fenestration design.

However, it became clear in the work that a more sophisticated analysis of buildings and user behaviour was necessary and this forms the concern of this paper.

From building simulations and analysis of results in previous research on fenestration,...

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Global PV systems results

The energy production of both systems in 2006 is presented in Fig. 6, and for 2007 is presented in Fig. 7. For the year of 2006, the maximum daily average energy produced took place in August, 64.5 kWh, and the minimum occurred in November, 39.33 kWh. In 2007, the maximum was

65.7 kWh in October and the minimum was in 39.7 kWh in February.



Fig. 6. Solar XXI – 2006 – Monthly average of the daily PV energy produced.



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The yearly total energy produced by the PV systems, is depicted in Table 5 and Table 6, varying from 19.4 MWh in 2006 to 20.2 MWh in 2007.

Table 5. Yearly energy produced by Solar XXI PV systems, 2006




EcA PRec

Central PV





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The strategy

Solar availability is quite high in Portugal, even during the heating season. This makes the direct capture of solar radiation (windows), the indirect collection for domestic hot water and space heating (thermal solar system) and eventually energy production (photovoltaics) advised. Large windows are mainly oriented south, increasing the useful solar gain during winter. Smaller areas are oriented east and west and minimal areas to north. Overhangs on south windows and exterior venetian blinds on all provide solar protection during summer.

High thermal inertia allows control over the inside temperature and combined with night ventilation, prevents overheating. In the bedrooms ventilation should take place in the evenings to avoid drafts during the sleeping period...

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Effect on Building Space Heating and Cooling Loads and Electricity Production

Table 3 presents the electricity production obtained with TRNSYS for the three BIPV curtainwall constructions (scenarios 2, 3 and 4). As it can be observed, systems in Yellowknife and Iqaluit generate approximately the same amount of electricity, whereas the ones in Montreal produce between 4 and 7% less electricity. This can be explained by Yellowknife and Iqaluit greater annual south-facing vertical radiation and lower ambient temperature throughout the year. This table also indicates that scenario 4 is the worst in terms of electricity generation with a production reduced by more than 22% compared to scenarios 2 and 3. The building heating and cooling loads for each one of the 5 scenarios and 3 cities considered are shown in Fig. 6...

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