Combined use of phase change material and thermal insulation to improve energy efficiency of residential buildings

There is an increasing need to improve the energy efficiency of residential buildings all around the world. Providing thermal insulation to the external walls and ceilings is a common practice for this purpose. The combined use of phase change materials (PCM) and thermal insulation in building envelopes could potentially further promote the building energy efficiency while avoiding overheating. This is evaluated in this paper by combining the use of expanded polystyrene and PCM gypsum board in the building envelope of a typical standalone Australian house. The evaluation was conducted through numerical simulation by considering the location of the house in three different Australian cities (Darwin, Alice Springs, and Sydney), which represent three different climate zones (tropical savanna, hot semi-arid, and humid subtropical). The results show that in a life cycle of 10 years, the total cost savings from the optimal combination of PCM board and insulation in Darwin, Alice Springs and Sydney are AU$167.0, $162.3 and $39.7/m2, respectively. Meanwhile, the energy ratings of the house are increased by 3.5, 3.8 and 4.3 stars in the three cities, respectively. The payback periods of the renovation range between 2.2 and 7.5 years, depending on the climate conditions.