Ventilation with outdoor air has been the accepted method for controlling moisture and overheating in residential attics. This is recognized in the Building Code which requires that the total vent area must be l/300th of the attic floor area. However, how much ventilation is provided and how this ventilation affects moisture accumulation in an attic are not well understood. The present study attempts to provide some answers to these questions. The study consists of two parts. First, detailed measurements were carried out in two separate attics located at a field test site.

Many occupants in modern buildings complain about the indoor climate and report medical symptoms which they ascribe to the indoor environment. These symptoms are common in the general population. Technical measurements in the buildings  mostly show concentrations and levels within accepted limits. A strategy is needed to handle these problems. One important part of this strategy is to use standardized questionnaires for structuring the information from the occupants.