Preliminary results of the WHO Frankfurt housing intervention project

Abstract
Thermal insulation of buildings is widely recognized for its economic benefits due to decreased energy costs and since residences are major consumers of energy, it is also considered an appropriate tool for reducing greenhouse emissions and mitigating climate change. Yet, little information exists on the potential health effects of thermal insulation, which is often accompanied by a decrease of air exchange rates in air-tight and highly insulated buildings.

The WHO housing and health programme therefore implemented a health-monitoring project in cooperation with a large housing agency based in Germany. The project collected data in spring 2006 before renovation work, and re-contacted all households in spring 2007 after renovation was carried out. In parallel, a control group of dwellings without interventions was used to collect additional data to identify changes caused by building rehabilitation in the intervention group. The main objective was to assess the impact of thermal insulation changes on indoor environments, and evaluate potential effects on residents’ health.

Drawing from 131 insulated and 104 non-insulated dwellings (with data for 220 and 155 residents, respectively), the project’s preliminary results indicate that thermal insulation had a strongly positive impact on thermal conditions and thermal comfort as perceived by the residents, and decreased relative humidity in renovated dwellings. Results for direct effects on the occurrence of mould in renovated dwellings were weak, but indicated the major role of humidity levels and air exchange for adequate indoor climate. Direct associations of thermal insulation with health effects were also weak and limited to smaller prevalence differences of respiratory diseases and cold. Additional effects of the refurbishment were increased satisfaction and living conditions as perceived by residents, and a clear reduction of noise exposure.

In conclusion, the first results indicate that renovation activities and insulation are not in conflict with the health of residents and have the potential to improve health-related living conditions and thermal comfort if the rehabilitation work is done professionally and considers the need for adequate air exchange.