Architecture, thermal design and energy performance of solar schools in Argentina

FILIPPÍN C.; FLORES LARSEN S.; ALICIA BEASCOCHEA,

Energy and Buildings: Efficiency, Air Quality and Conservation

NOVA Publishers

Lugar: New York; Año: 2008;

In Argentina the percentage of the heating energy consumption in buildings is around 30%. In the school buildings in the province of La Pampa (in the central region of Argentina, among 35 and 39º of south latitude) the percentage of heating energy is around 90% (10% = electricity consumption = lighting and appliances). The measured energy consumption is superior that the value estimated according the Volumetric Heat Loss Coefficients (G-value) and Base Temperature (18ºC), situation that indicates that the students and teachers work with superior temperatures to that value. The cost of the consumed energy corresponds to 17% of the total spent by student. In this context two solar schools (Promoter Entity: Ministry of Culture and Education) were built in different regions, one of great agricultural potential - cattleman (Catriló in the East); the other, semi-arid, with low population density (Algarrobo del Aguila West). Both buildings were designed with passive solar design strategies that exploits the building´s orientation, shape, materials, windows, and external landscaping, in combination with other energy efficiency measures: passive solar heating systems (direct solar gains through transparent areas and ventilated facade panels) and cooling (natural ventilation and earth-to-air heat exchange through buried pipes) , to create a pleasant environment which is less dependent on fossil fuels based energy. The schools were evaluated through the results of the thermal monitoring and the surveys (to analyse the behaviour of the occupants, who explicitly control and affect the internal environment). In the school located in the West of the province the occupants (in their majority with two or three garments - Tshirt, sweater and jacket –inside the classroom) were in comfort with temperatures stockings of 17ºC, the heating practically doesn´t light during the day and goes out at night. The energy saving in heating is of 90%. In the solar school located in the East of the province the daily temperature average in the classrooms is around 21ºC in the winter. The students only remain in the interior with two garments - Tshirt, sweater - or only with the pinafore. The heating remains lit during the night and the energy saving is of 50%. The results show that the area of comfort doesn´t have real limits, it is defined by those conditions in which a feeling of annoyance doesn´t take place. The implementation of passive solar design strategies allowed an energy saving in heating around 50 and 90%, what in turn means a reduction of CO2 emissions. In the case of non-residential buildings, through the technology applied to the envelope design in solar school buildings, the G value was reduced in 35 %, decreasing from 1.40 W/m3ºC (average for conventional school buildings in La Pampa) to 0.97 and 0.90 W/m3ºC at schools in Catriló (East) and Algarrobo del Aguila (West), respectively. The use of solar technology allowed for the noticeable reduction of natural gas consumption in heating, constituting a major contribution in areas of temperate to cold climate, where the greatest energy consumption in buildings corresponds to heating. In view of these G values and direct gain values oscillating between 11 and 14 % of the building´s useful area, a solar school building may consume at least 50 % less energy in heating to meet occupants´ comfort standards. In the case of the school built in the West,-average temperature 17ºC- consumption was equivalent to the 15% of the average of energy consumed by other schools located in different parts of the province. The qualitative and quantitative analyses carried out showed promising results related to the buildings energy behaviour, yet it cannot be denied that there are certain factors that have direct incidence on the optimal energy behaviour of buildings and their thermal comfort: a) exogenous factors (the high variability of the external physical environment), (b) endogenous factors (construction characteristics) and c) socioenvironmental factors ( life-styles and behaviour of dwellers, associated to the active energy contribution and use of heating ). The true challenge for solar energy architecture is to simplify technology and construction processes so that costs would not be more higher than those for conventional buildings, assuring users´ pro-active behaviour towards the building´s correct thermal management. To involve users in these improved practices is still another challenge.