The application of the regulations minimal solar collector area

Following the new regulations, a three bedrooms autonomous zone must have a minimal collector area of 4 m2 independently of the climate zone were is located. From the simulations results mentioned in chapter 5.4 we took the maximum value for Esolar that was 2083kWh/year in Alandroal (I1V3). What happens if we would like to reach on the others localities the same energy achieved in this one? The results have showed that just one location can reach almost that value with the minimal required area (4 m2), the other need more area (Fig 2.). It was made also calculations to see what the maximal SCA without having significant energy dissipations (overheating). This means that adopting just the regulation minimal collector area we can be wasting solar energy in some climatic zones that could have more potential. Of course we could adopt more efficient collectors to reach a higher value but, as it usual, many designers are going to follow strictly the imposed area and even will try to reduce it to save in costs and to achieve an easily integration in roofs. Calculating the minimal collector area for the rest of the localities (maintaining the same collector efficiency) to reach the same Esolar of Alandroal, resulted, in most of them, panel area increments of 0,5 m2 to 2,5 m2. In face of this, it seems it would be more effective to evolve the requirements to a minimal Esolar value per household adapted to different climatic zones or groups of zones. This would permit a better energy efficient /cost collector selection with not less energy efficiency management.



■ maximum solar collector area


■ solar collector area to achieve the same Esolar value



Fig 2. – Maximum SCA / SCA to achieve the same Esolar in the nine different localities.

3. Conclusions

Without any doubts, the new Thermal Regulations brings new challenges for the building design and construction industry activities and represents a start point to further advances in building sustainability and energy efficiency. After analyse the critical aspects concerning the implementation of solar collectors in Portugal, it was noticed that collectors market has conditions nowadays to grow towards a solid and income-producing market. But other conclusions could be taken. Portuguese Civil Engineers project designers are still not sufficient prepared to deal with this new technology although they are struggling to adapt to regulations and looking for training. By other means, high education institutions should adapt their Civil Engineer courses to give more competencies in these matters. Also, an adequate selection of the equipment system turns out to be a very important procedure to meet the regulations requirements. The building water supply design project, principally for multi-residential buildings, is facing important conceptual changes. Also, a repair and maintenance building design project, so long discussed and requested, turns to be even more essential. Architects have also here a very important role on the integration of solar collector on buildings as they could, among other things, design roof tilt angles adapted to solar collector optimal angles. But we must not forget we need government polices to provide minimal guarantees to building sun exposure. Relatively to the minimal regulations collector area, it seems that adopting just this area we can be wasting solar energy in some climatic zones that have more potential. A minimal Esolar value per household adapted to different climatic zones could guide better the designers to get more project design quality. Finally, we realize that, much work must be done but the changes imposed by new regulations should be seen as an opportunity to take the initial steps to more effective energy efficient construction in buildings.


[1] European Union Directive 2002/91/CE of 4 of January 2003.

[2] Portuguese Government, Decree Law 80/2006 of 4th April.

[3] ADENE, INETI, SPES, APISOLAR, MEI, DGGE, Hot Water Program for Portugal (IP-AQSpP), www. aguaquentesolar. com.

[4] DGGE & Ministry of Economy and Innovation (MEI), (2008) Portugal Efficiency 2015 – National Plan for Energy Efficiency (PNAEE), DGGE & MEI, Lisbon.

[5] Weiss, W., Faninger, G, (2002) Solar Thermal Collector Market in IEA Member Countries, IEA Solar Heating & Cooling Programme, Austria.

[6] Portuguese Observatory for Solar Thermal, (2003, 2004, 2005, 2006) Characterization of Solar Thermal in Portugal, ADENE & IP-AQSpP, Lisbon.

[7] National Institution for Energy and Geology (DGGE), (2004) The Solar Collectors Use for Domestic Water Heating, DGGE & IP-AQSpP, Lisbon.

[8] NHBC (2007), Guide to Renewable Energy, NHBC Technical, Amersham, Bucks, UK.

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