Occupant satisfaction with indoor environmental quality and health after energy retrofits of multi-family buildings: Results from INSULAtE-project

Background: Driven by climate change mitigation, EU countries are committed to improve energy efficiency of their building stock by implementing the energy performance of buildings directive (EPBD). Should higher energy efficiency result in better indoor environmental quality (IEQ), this policy could also be seen as an opportunity to improve public health across Europe. Objectives: This paper focuses on the assessment of the effects of energy retrofits on occupant satisfaction with IEQ and health in multifamily buildings. Methods: Data on occupant satisfaction with IEQ and health were collected from the occupants of 39 Finnish and 15 Lithuanian multifamily buildings (an average of five apartments per building, one adult per apartment) both before and after energy retrofits (such as improving thermal insulation, windows, heating and/or ventilation systems). Parallel to the data collected from the occupants, data on several IEQ parameters, including temperature, temperature factor, and air change rate, were collected from their apartments. Moreover, data from seven Finnish and five Lithuanian non-retrofitted control buildings were collected according to the same protocol. Results: Occupant satisfaction regarding indoor temperature was associated with both retrofit status (OR 5.3, 95% CI 2.6-11.0) and measured IEQ parameters (indoor temperature OR 1.4 per 1 degrees C increase, temperature factor OR 1.1 per 1% increase, and air change rate OR 5.6 per 1/h increase). Additional positive associations were found between retrofit status and occupants reporting absence of upper respiratory symptoms (OR 1.8, 95% CI 1.1-2.9) as well as not missing work or school due to respiratory infections (OR 4.1, 95% CI 1.2-13.8), however, these associations were independent of the measured IEQ parameters. Conclusions: There seems to be a strong subjective component related to the observed changes in occupant satisfaction with IEQ and health as a result of energy retrofitting in buildings. Further studies are needed to verify the actual mechanisms, as well as possible long term effects.