Air Permeability Pressure Tests

Air Tightness Testing

We are working with qualified assessors to provide air leakage tests for domestic and commercial buildings.

• What is the air tightness test?
• What is the test procedure?
• What types of preparations are required before the air tightness tests?
• How long would it take to carry out the test?
• Is air permeability test mandatory?

What is the air tightness test?

Air tightness test is as an air permeability test, which is carried out by a professional testing company to identify the volume of air escaping from the building. Irrespective of building regulations requirements (Part L1A conservation of fuel and power in new dwellings and Part L2 conservation of fuel and power in Non-dwellings), pressure testing provides some benefits. They provide clear guidance on how to make buildings more energy efficient, cost effective and comfortable.

It also helps to reduce energy consumption and carbon emissions. Air tight buildings prevent conditioned air escaping from the building and any unwanted cold draughts.

What is the test procedure?

Air tightness testing is carried out in accordance with the procedures detailed in ATTMA TSL1 for Part L1A conservation of fuel and power in new dwellings and ATTMA TSL2 for Part L2 conservation of fuel and power in new non-dwellings.

Air permeability is expressed as volume flow per hour (m3 h-1) of air supplied to the space per square metre (m-2) of envelope area for an internal to external pressure difference at 50 Pa.

The air permeability test involves connecting a series of small fans, or a large fan, to a suitable aperture in the building envelope (which is normally the entrance door) and pressurising it over a range of pressure differences.

The fan speed is increased in specific intervals up to a maximum and then subsequently decreased.

Air volume flow rate through the fan (equal to the air escaping through the building envelope, such as gaps and uncovered holes) and the pressure difference across the building envelope are recorded at each fan speed.

In calculating air permeability, corrections are made for temperature and barometric pressure.

What types of preparations are required before the air tightness tests?

Before the test is carried out, exhaust fans, kitchen hoods and ventilation systems must be thoroughly sealed. Sealing can be achieved with covering the grilles with strong sheets of metal, wood or plastic and appropriate use of strong adhesive tape. Drainage traps should also be filled.

While the pressurisation test is being carried out all external doors and windows must be closed and secured to avoid them being blown open. It is also recommended to tape off all the vents on the windows. Internal doors must to be wedged open during the test to avoid them inappropriately slamming.

The fan unit will create draughts in the building. Lightweight objects and paper near the fan unit should be removed to avoid them being blown away. Large objects such as fixtures and furniture will not be affected.

Access in and out of the building during the test will not be possible (unless there is an emergency and a need to evacuate the building).

There are no health risks to site workers who will remain in the building while the air pressure test is being carried out. However, there may be some discomfort due to cold draughts and some noise from the fan.

How long would it take to carry out the test?

The test will take approximately 30-100 minutes for dwelling and up to three times that level for commercial buildings depends on the size of the respective dwelling.

Is air permeability test mandatory?

Yes and is based upon the Part L regulation that states buildings need to demonstrate a minimum level of air permeability (10m³/(h.m²)). However, the energy assessor will identify (in SAP report or SBEM report as a design air permeability) what is the minimum requirement, and which figure should be achieved. For a specific building may need to drop lower in order to achieve the overall carbon emission rate.