An air-tightness test measures the flow of air both in and out of a building. Improved air tightness reduces unwanted air leakage where air 'leaks' through gaps and cracks in the building fabric.
An air-tightness test will highlight these 'leaks' or areas of heat loss.
The only satisfactory way to measure air tightness is by using blower door test equipment.
An air-tightness test is only legally required on new dwellings, however it can be very helpful in detecting air leakage in existing dwellings
Improving the air-tightness of a poorly sealed house could cut heating bills by up to 30% while also greatly improving the comfort of the dwelling.