The impact of climate change on indoor climate and energy use in passive houses

Purpose: The purpose of this study is to contribute with knowledge about how the warming effects of climate change may affect indoor living standards, considering that we are already living with some over-temperatures during the summer time. The specific aim is therefore to show how thermal climate in warm passive houses will be perceived, and how specific energy consumption will be affected, within the near future in southern Sweden. Method: To order to achieve the aim, a specific scenario of future temperatures had to be defined. Official climate data for the year 2050 in Gothenburg was collected and compiled. A certified passive house was theoretically exposed to the expected future climate and indoor temperature as well as energy consumption was calculated. Calculations were made using the energy calculation software BV2 for reference conditions and adaptions of both climate as well as technical solutions for greater thermal comfort. Findings: A climate scenario for Gothenburg during year 2050 illustrates that the average year-temperature increases from +7.7°C to +9.9°C. The largest change can be observed during the winter, with an increase peaking at +2.5 ºC. The results show an increase from 65 to 107 number of days during the year in which the studied passive house has an inadequate indoor temperature, as a consequence of over-temperatures. One method for thermal climate enhancing, using a combination of sun screening and air conditioning powered by solar cells, showed having good impact without considerably affecting the specific energy consumption. Implications: In a passive house without air conditioning, the thermal indoor climate will reach an unacceptable level for the tenants, more often in the year 2050, than during the reference period, due to warmer outside temperatures. The method which has the smallest impact upon the energy consumption is sun screening, while air conditioning is the most effective, but also very energy consuming. In order to optimally conserve the thermal indoor climate without decreasing the free energy during the winter, one should install both sun screening and air conditioning in their passive house. Limitations: The result is applicable on passive houses within climate zone III, but the general conclusions made applies for all passive houses in Sweden. Using different methods of calculating the indoor temperature may result in variable results. Keywords: Climate change, Passive house, Indoor climate, Thermal comfort, Energy consumptio