Comparative study of energy consumption for air conditioning between residential buildings with two different subflooring systems

Energy consumed by heating, ventilation and air conditioning account for about 40% of the total energy used in an average Australian home. The main feature that categorizes the construction systems is the thermal mass as it contributes directly to the thermal performance of the entire house. High thermal mass flooring and walls are most appropriate in climate with high diurnal (day-night) temperature ranges. High thermal mass construction system has higher embodied energy but this can offset by reducing heating and cooling energy consumption over the life span of the house. The optimum design, in terms of desirable heat gain or loss, can be achieved by considering the building orientation, thermal mass and careful design of the building envelope including roof, walls, windows and floor systems. To demonstrate relative advantage in terms of energy conservation between houses with different construction systems and thermal mass, two model houses which are detached dwelling with a floor area of 200 sqm and with two levels and four bedrooms were selected in this study. One of the model houses represented modern house with brick veneer walls and concrete slab-on-ground flooring (high thermal mass Model). The second model house represented old house with fibro walls and raised subfloor (low thermal mass Model). The analysis has been carried out using computer software (IDA ICE). The energy performance of the buildings were computed and compared. The results show that the modern house consumed 53% less energy compared to old house and hence the former is significantly cost effective over the long run