BSRIA Technical Note TN 5/86: Building Airtightness and Ventilation - An Overview of International Practice

Fresh air is required in buildings both to satisfy the respiratory needs of occupants and to dilute and disperse internally generated pollution. Although an inexhaustible supply of fresh air is almost always available, excessive rates of air exchange can add substantially to a building's space heating, cooling and humidification load. It may also create an uncomfortable, draughty environment. Thus, in general, it is desirable to match the supply of outside air to internal needs. The minimum fresh air supply necessary to meet metabolic needs is estimated to vary between 1.0 and 9.0 1/s/person according to the intensity of activity. On the other hand much higher rates are required to maintain adequate indoor air quality and it is this problem that normally dictates overall ventilation requirements.

Principally for reasons of health and safety, many countries have introduced legislation, codes and standards aimed at ensuring the adequate ventilation of occupied premises. More recently, a number of standards have also been introduced in an attempt to minimise unnecessary energy waste through excessive ventilation. In some countries airtightness requirements governing the entire building structure have been introduced. This report compares and contrasts the background behind some of these standards and practices for the purpose of evaluating their suitability and impact on conditions in the United Kingdom . Although not intended as an exhaustive document on standards, a set of appendices containing a summary of standards from many countries is included for reference purposes.