Optimum Facade Design for Minimization of Heating and Cooling Demand in Commercial Office Buildings in Australian Cities

The effectiveness of thermal mass and night ventilation in reducing cooling demand in commercial buildings has long been established. However, the appropriate configuration of facades has been determined for only a few locations without any clear design framework across different climate zones. Research on Australian climate zones is particularly limited, and in general, night ventilation has not often been incorporated in previous research, whereas for most new building designs, the use of economizer cycles is essentially a standard feature in HVAC design. A comprehensive energy analysis was completed in which the impact of external and internally insulated facades with and without thermal mass was investigated. The study considered varying internal loads and covered building locations in cold, mixed, warm, and hot climates around the world, with a particular focus on Australian locations. Although the focus was specifically on Australian cities, selected international climate zones were included for additional relevance. It was demonstrated that high-level comparisons between international climate zones are not sufficient to inform engineers and building designers of requirements for local conditions. Current international research on passive thermal mass, although informative, does not answer all required questions for Australian localities. It was demonstrated that thermal mass has little value in heating-dominated climates, but is more important than insulation in the facade in cooling-dominated climates. With higher internal loads, internally coupled thermal mass became more critical. In hot and warm climates, a composite structure with insulation sandwiched between layers of thermal mass achieved the lowest amount of heating and cooling required.