Comparison of passive cooling techniques in improving thermal comfort of occupants of a pre-fabricated building

Abstract

Pre-fabricated composite buildings are proposed as sustainable sheltering and housing solutions for developing countries. This work compares different passive cooling techniques of shading, natural ventilation, cool painting and increase in thickness of interior gypsum plaster for these buildings to tackle overheating in hot climates. The studied techniques are measured and compared in terms of indoor air temperature by calculating four indicators of maximum, minimum, average of highest 5% and average of lowest 5% temperatures as well as thermal comfort of the occupants based on two acceptability rates of ASHRAE 55 and three acceptability limits of EN 15251 standards in three climates: Porto, Nairobi and Mumbai. The findings of this comparison bring insights into the effectiveness of passive cooling techniques, that can be highly beneficial at design level. Results point out improvements by all studied techniques, even if these quantitatively depend on the presence of the occupants and the choice of the performance indicators. Finally, further indicators such as stored heat, solar radiation heat gain and surface temperature are analyzed, to explain causes and effects associated with studied passive cooling techniques. Results of these comparisons pointed out that the combined implementation of all techniques combined is effective enough to provide thermal comfort of the occupants during almost all annual occupancy in Nairobi measured by acceptability rate of 80% of ASHRAE 55 and Category III of EN 15251.