Proposal for airtightness requirements. Rakennusten tiiviysvaatimusten maarittely.

The share of ventilation in the energy demand in Finnish building stock is about 50 per cent. An essential part of the ventilation heat losses is uncontrolled due to air infiltration, which only partly serves the demand of ventilation. The aim of improving the airtightness of windows and other leakpoints is to prevent the infiltration. But then, if the supply air intake is not mechanical, certain risks of insufficient ventilation occur. In thereport, the interconnection between the building envelope and ventilation system is studied. As a result of the study, a preliminary suggestion for airtightness requirements is presented, both for new and existing buildings. In developing the suggestion, the performance and costs of the constructions and ventilation systems, to achieve good airtightness and sufficient controlled ventilation, are taken into account. If requirements for airtightness are given, also methods for measuring the airtightness and air change rates are necessary. The measurement methodics for different types of buildings, also existing, is presented. Detailed instructions for measuring are, however, written in a separate report, The need and costs of controlling the workmanship are briefly described. Finally, the whole Air Infiltration Research is summarised.