Air Pressure Testing, Air Permeability and Building Leakage
In this blog we deep dive into the what, when and how of Part L Air Testing.
In today’s eco-conscious world, property owners are increasingly turning to air tightness testing to:
- Minimise their environmental impact
- Reduce energy bills
- Curb energy waste
As air tightness testing becomes a standard part of Building Regulations, both domestic and non-domestic new builds must adhere to rigorous air tightness standards.
Understanding the intricacies of air testing is vital for ensuring compliance and optimising energy efficiency. However, let’s first clarify what Part L and air testing are?
What is Part L Air Testing?
Part L of the UK Building Regulations focuses on the conservation of fuel and power, aiming to improve the energy efficiency of buildings by setting standards for insulation, heating systems, and airtightness.
A key component is air permeability testing, which measures how much air leaks through a building’s fabric. This is also referred to as air pressure, air tightness or air leakage testing.
Testing assesses the level of conditioned (heated or cooled) air leakage. This is known as infiltration, evidently felt as uncontrolled ventilation. The test measures the amount of air leakage in cubic meters per square meter of internal surface area of the building.
Essentially, it gauges how much air escapes through gaps or building fabrics. An airtight building minimises energy wastage by preventing heated air from escaping.
When is Air Testing required?
Since 2006, all new developments in the UK are mandated to undergo air tightness testing as part of approved Building Regulations. If your home was built before this date, which is estimated to be around 38% of UK homes, it is unlikely that air tightness was even considered during construction, let alone tested. Likewise if your home has had a loft conversion or extension!
At the time of writing this blog, testing is mandatory for all new homes and large extensions, ensuring they meet a maximum air permeability rate—currently set at 8 m³/h·m² at 50 Pascals in England and Wales using the blower door methodology.
We also recommend air tightness testing existing homes when major building works or retrofits are carried out or if a new energy performance certificate is commissioned.
Testing can be carried out at any point during construction so long as there is power and the external building envelope is complete.
However to produce a valid certificate (with no deviations from the required test standard) testing should be carried out at the point of handover and/or completion.
How is a Blower Door Air Pressure Test carried out?
At Building Compliance Testing an air test is typically carried out by a single engineer using a UKAS calibrated blower door system. The system is essentially a fan mounted within a canvas, that’s installed within an external opening, such as a door or window. The fan is controlled by a fan speed controller, and a number of tubes connected to a multi-channel manometer, used to measure pressure differential.
Before and after the test, building static pressures, internal and external temperatures and barometric pressures at recorded which is read and inputted into a software to generate a result.
Generally during this time other trades can remain within the building so long as the external envelope remains closed (external doors and windows) and internal doors open.
Typically the test takes between twenty minutes to a couple of hours. However, this all depends of the size of the building, the test locations, the ability to create stable pressure in the building and unfortunately the controllable influence of the British weather.
An alternative approved testing methodology is Pulse. You can learn more about Pulse Testing by clicking here.