Evaluating indoor environment of a retrofitted multi-family building with improved energy performance in Sweden

• Three methods: measurements, simulation and a survey have been combined and used in the current study.
• The retrofitted building's space heating demand was reduced by 39%.
• The study shows that the retrofit has positive effects on the indoor environment.
• By adding external blinds during a special time period seems to be the best option for improving the indoor climate.

The building sector within both the EU and Sweden accounts for about 40% of total energy use. It is therefore important to introduce energy efficiency measures in this sector in order to meet the national implementation of the Building Performance Directive. Retrofits that result in improved energy performance are important in order to meet national energy targets, but the impact on the indoor environment has to be considered. Properly chosen energy efficiency measures may affect the indoor environment positively. One retrofitted multi-family building, located in the city of Linköping, Sweden, was chosen as the study object. The building represents a common type of construction in Sweden. This study presents an evaluation of both the indoor environment and energy use of the retrofitted building in comparison with a similar non-retrofitted building from the same area. The results show that the building has potential to reach a 39% reduction of space heating demand. The indoor environment has been improved compared to the non-retrofitted building. Adding external blinds from 15 May to 15 September between 10am–12pm on the east side and 12pm–3pm on the west side seems to be the best option for improving the indoor climate during summer.