humidity

As part of the energy and indoor climate survey recently carried out in Sweden (the ELIE study) a simple, inexpensive but reliable passive sampler for estimating monthly averages of relative humidity has been developed. The diffusion sampler consists of a 5 ml plastic tube prepared with lithium chloride monohydrate as trapping medium. After necessary calibration of this particular design of sampler the relative humidity can be calculated from the weight change of the sampler, the time of sampling and the average temperature during this period.

Questionnaire reports on symptoms and sensations from 4943 office workers, measurements of indoor climate from 540 office rooms in 160 buildings, and measurements of TVOC in 85 rooms were used in an analysis of the role of indoor air humidity and the sensation of dryness as risk indicators of SES (Sick Building Syndrome) symptoms. The sensation of dryness was strongly associated with the prevalence of SBS symptom reports. There were no associations between measured indoor air humidity and the prevalence of SBS symptoms or the sensation of dryness.

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.