First-phase occupant reaction to well-sealed indoor environments.

Possible health effects and changes in sensation of comfort among tenants after replacement of single glass windows in leaky frames with double glass windows in airtight frames have been studied. The study design was observational, and included a study group and a corresponding control group. The results indicate essential improvements of the indoor climate and of the health status of the tenants after replacement of the windows (i.e. positive effects on temperature conditions, lowering of noise, fewer symptoms related to mucosal surfaces, fewer rheumatic symptoms, and possibly fewer headaches). Significant changes in complaints or health effects which could be related to reduced air quality caused by the airtightening were not found. This study cannot give any evidence of inconveniences that may occur later if the apartments become too airtight.