The importance of internal thermal mass to the thermal performance of housing

Housing which has good thermal performance provides a steady and comfortable internal environment and has less energy consumption regardless of the weather conditions. The contribution of thermal mass is well recognized, however the influence of heavy (masonry) internal partition walls and concrete floor slabs is often passed over when considering the enhancement of the overall thermal performance. The impact of the internal thermal mass of masonry components, in the form of internal partition walls and the interior leaf of multi-layered enclosure walls, on the overall temperature variations and energy consumption of housing is investigated in the paper. The results are based on a detailed study of the performance of several full scale housing test modules incorporating a range of typical Australian walling systems. The study confirmed the premise that the thermal resistance (R-value) alone (a steady-state parameter) cannot represent the actual dynamic thermal performance of a building. The relative performance of the walling systems varied with season, but in general, the thermal mass of the partition walls and the internal skins of the enclosure walling systems were effective in absorbing energy from solar ingress and dampening the effects of the external diurnal temperature swings. This influence improves the thermal performance and has the potential to minimise the need for artificial heating and cooling in both new dwellings and in the retrofitting of existing houses.