Ventilative cooling potential in low-energy dwellings : the HoTT case study

Research indicates that low-energy dwellings are more sensitive to overheating than regular dwellings. In this research the ventilative cooling potential of low-energy dwellings is considered. A low-energy dwelling based on the Active House concept, “House of Tomorrow Today” (HoTT), has been investigated as representative for
low-energy dwellings in general. A computational model of the house was created with the software TRNSYS (in combination with CONTAM) and this model has been calibrated with actual (intervention) measurements in the HoTT. The potential of creating or maintaining thermal comfort in the house by applying ventilative cooling has been considered. The simulation results show that ventilative cooling in combination with other design requirements (sun shading and thermal mass) is able to significantly reduce the overheating potential for current typical Dutch summer climate conditions and provide with that a more robust solution for future climate developments with less need for active cooling. Lack of inclusion of these design
principles will affect the indoor conditions significantly. As HoTT applies a relative lightweight construction the advantage of thermal mass is less well exploited. However, in an overheating situation, the potential of ventilative cooling in the current HoTT-design can be increased, i.e. higher air change rates can be obtained, by enlarging the currently fixed limited atrium window opening areas. The results confirm that overheating mitigation is an integral design problem.