All buildings suffer from infiltration to a greater or lesser extent – this is air movement through cracks and holes in the building. Infiltration is worse under adverse weather conditions and the air movement leads to energy losses. This is often referred to as the air tightness of the building.
An airtightness test is a way of quantifying how leaky the building fabric is, and a blower door test is specified under Part L of the Building Regulations for new dwellings. An air pressure test involves maintaining a pressure difference between inside and outside the building and measuring the volume of air required to maintain that difference.
The test is equally valuable for existing homes as it will help to identify where energy losses are and is even more valuable when used in combination with thermal imaging, as we do at Green Footsteps.