Summary

The need for adequate ventilation of buildings is recognised as part of UK Building Regulations and guidance on meeting requirements is given in Approved Document F (ADF).

The current provisions have been developed to allow the occupants to achieve a whole-house air exchange rate of about 0.5 air changes per hour (ach). The current project investigated ventilation and indoor air quality (IAQ) in homes in England built since 1995, which is the date of the last revision of Approved Document F (ADF). The main part of the project involved a winter (January–March 2002) and summer (July–September 2002) period of monitoring of nitrogen dioxide (NO2), carbon monoxide (CO), formaldehyde (HCHO), volatile organic compounds (VOCs), particulates (PM10), temperature and humidity in a sample of 37 homes in England. The study group includes different types of dwelling in various locations. All homes were naturally ventilated but, in bathrooms and kitchens, 34 homes had extract fans and three had passive stack ventilators. All homes in the study had central heating with radiators. Three homes used only electricity for cooking, 11 homes used only gas as cooking fuel and 23 homes used both electricity and gas for cooking. No homes used bottled gas for heating or cooking.

Indoor air pollutant measurements were taken simultaneously with measurements of the air exchange rate of the indoor air with the outdoors using a perfluorocarbon tracer (PFT) technique. The airtightness of the structure was also determined for each home using a pressurisation test. Subsequently more detailed measurements of pollutants and ventilation were undertaken during the peak levels study. This involved a winter (January–March 2003) and summer (June–August 2003) period of sampling in five homes selected on the basis of high relative humidity, high indoor air pollutant concentrations and low ventilation rates.

The results from the measurements were statistically analysed, based on data from questionnaires, including house characteristics and occupant activity diaries. The statistical analysis includes two stages: simple descriptive statistics of the indoor air quality parameters and ventilation rates measured under different conditions (location, dwelling type etc) and bivariate analysis to identify associations between these and possible determinants (e.g. NO2 and the presence of a gas cooker). It should be noted that a wide range of variables may influence air quality and ventilation including household characteristics, occupancy, location, meteorological conditions and indoor sources. Therefore a larger study may find additional statistically significant relationships between such factors and air quality and ventilation that are not depicted in a study of 37 homes.

Results from the measurements and statistical analysis may be summarised as follows: