What does it mean?
Air Tightness Testing, commonly refereed to as Air Testing, Air Leakage Testing and Air Pressure Testing, is an accurate way of measuring exactly how much air / heating is leaking out of the building fabric. Air Tightness Testing is effectively measuring how much heat / energy the property would be wasting via gaps and cracks. The Air Tightness Test doesn’t only tell you how much leakage is taking place, it is also aids leak identification.
Air leakage is the uncontrolled flow of air through gaps and cracks in the fabric (which in the real world relate to drafts and infiltration) and is not ventilation, which is the controlled flow of air in and out of the building.
Air Tightness Testing was put in place to improve the energy efficiency of all new developments. Too much air leakage leads to unnecessary heat loss and discomfort for the occupants. As the Government strives to reduce CO2 emissions from new buildings, building regulations now place greater emphasis on the quality of the fabric of the building.
How is the test carried out?
Here at Anglia Air Testing we are fully qualified & Registered ATTMA Testers. We are also qualified to carry out Ventilation Testing and MVHR Commissioning. We complete all testing under the strict guidelines and regulations of ATTMA, the Air Tightness Testing Measurement Association.
The first thing we do before the Air Tightness Test takes place is our temporary sealing. One conducting an Air Test, there are a few elements in the buildings fabric we are authorised to seal prior to the test. These are as follows:
- Mechanical Ventilation (Extractors, MVHR & Air Handling)
- Trickle Vents
- Air Conditioning
- Passive Ventilation
- Chimney Flues
A common worry for developers is that all other trades must stop work while the test is taking place, and everyone must vacate the building. This is incorrect. All trades working inside the building can continue as normal, but once the test has started, no one can come in and no one can leave.
To carry out an Air Tightness Test, a large BSRIA calibrated Fan is placed in the front door. We then connect this fan to our hand set, used to control the fan and to take readings from the fan. This equipment then allows us to get an idea of the Air Tightness of the building. Once the fan is in place, we draw air from inside the building, dropping the pressure inside by 50Pa. This then causes the outside world to try and fill the house and balance the two pressures.
We then take 10 readings from our equipment, then plotting a graph of building pressure against fan pressure. The testing is measured in air flow m3 over an average hour period at an average of 50Pa for every m2 of building fabric. We then put these figures into our software, which then tells us the design air permeability @50pa. Which is the figure your building control / Sap Assessor are interested in.
How to pass an Air Tightness Test
Our first rule is not to rush yourself. We always find, the nearer the building is to completion, the more likely it is to pass. This being said, it is always possible to pass an Air Test at an earlier stage of construction, but it is all down to how the building was constructed and sealed through the previous stages. Common issues are as follows:
- Pipes not sealed around, leaks from behing boxing, under bath, around toilet waste etc.
- Plugs, sockets and light fittings left unfitted, down lighters hanging down.
- No power – mains 240v electricity MUST be available to power our fan, a generator doesn’t give a steady current producing erratic results.
- Loft hatch not fitted.
- Sanitary ware and kitchen not properly fitted and sealed.
- Leaks from behind plasterboard, where dot and dab it’s good practice to foam the bottom of plasterboard before fitting skirting or using sealant to fill the gap between the skirting and the floor.
If all of the above issues are resolved before we arrive, you should be on the way to passing your Air Tightness Test. When we book you in for the Air Tightness Test, we always send you a confirmation email. Attached to this is a pre-test check list. We always advise you run through this, one by one. We also have a printable pre-test checklist on our website on our Advice & Support page.
If you have any further questions relating to Air Tightness Testing, please get in touch and we will do our best to assist you.