Author
D J HARRIS and P M KÄKELÄ
H+H Celcon, UK
H+H Siporex Oy, Finland

Abstract
The affect of air leakage through the envelope of a building has for many years formed part of the energy regulations in a number of European countries. However, it has not been until the latest changes in England and Wales to the Building Regulations that this characteristic, now referred to as airtightness, has been recognised in the calculation of energy loss in domestic properties. The regulations also require that type testing should be carried out on a sample of dwelling to ensure that the proposed level of airtightness is being achieved. This paper reviews some of the results of tests undertaken in Europe to measure the air leakage of different types of masonry construction, shows the benefits of using Autoclaved Aerated Concrete (AAC) masonry and compares to timber framed constructions. It describes the test method employed and the effect that airtightness has on the energy loss using the calculation method provided.