Future issues due to overheating in New Zealand houses

Abstract

Analysis of heating and cooling loads taken from a sample of 110 award-winning New Zealand houses has revealed that cooling loads are increasing at a rate 12 times faster than heating loads. In addition to this, further research showed that a house with 100% glazing could comply with the New Zealand Building Code in certain areas of the country when the Building Research Association of New Zealand Annual Loss Factor (BRANZ ALF) tool was used. This research showed that 10- 30% glazing is optimal in New Zealand, so these findings have significant implications on building performance. The houses in the research sample may not have a huge impact on New Zealand’s energy consumption themselves, but the publicity of these houses has a trickledown effect, with these celebrated architectural styles then influencing design trends. Architectural style has a direct effect on the energy use of the building. Large areas of glazing, inadequate solar protection, poor ventilation and lightweight construction all increase the energy use in houses, in both summer and winter. Summertime overheating is especially relevant with climate change predicted to increase summertime temperatures and lead to more days over 25°C, which is perceived as uncomfortable inside a house. Overheating also needs to be considered because it has never been strongly addressed in New Zealand, with the focus traditionally on heating, not cooling, New Zealand houses. With trends that lead to an increase in overheating and the uptake of mechanical ventilation, such as heat pumps, the consequential cooling cools will likely result in extreme summertime peak electricity use, placing a new demand on an already strained national grid.