In accordance with building regulations in the UK, it is mandatory to produce measurements for air leakage for newly built homes. Tests to determine the air permeability figures of a dwelling can also be referred to as an air pressure or air tightness test.
On completion of a build, a key component of our business is testing for air tightness. Testing for air tightness is critical for any build. Results affect a building’s energy performance.
SAP calculations are used to work out the energy performance of a residential building, one target component of the assessment is an air permeability test that measures the air leakage of the dwelling.
There are various factors that can affect an air tightness testing, but as a rule of thumb, the target figure for new builds is 5m3/hm2 or under (air leakage rate/hour, for each square metre).
This ‘pass or fail’ result is generated by a specialist engineer and indicates how much air is being sucked into a building — known as ‘leakage’— when the fan used to make such calculations functions at 50 Pascals.
Tests of this sort measure uncontrolled air leakage. They do not take account of trickle vents, extractor fans, or ventilation technology covered in Part F building regulation testing. Pre-designed ventilation inlets and outlets are sealed in advance of the testing. In this sense, air permeability testing identifies fissures in the building’s fabric.
At Briary Energy, we have a team of qualified testing experts who can help you with the air pressure test of your new build. The SAP Assessment needs to be carried out, as this sets the standard of the air permeability test that is about to be carried out.
An air tightness test will take a look at the following in your property:
After changes to Part L building regulations in 2010, air tightness tests must be carried out on three dwellings of each type, or 50% of residential buildings, whichever is lower.
Air permeability tests are required if you are building a new residential dwelling or a new commercial building.
Our recommendation is to conduct air leak testing after the completion of all building work (including snagging) —when all doors and windows have been fully fitted and the property connected to power and water supplies.
For perfect air tightness testing conditions, test before laying flooring or the installation of furnishings.
There are certification methods that set out to exceed building regulation standards – Passivhaus, for example, permits new builds an upper limit of only 0.6 changes of air per hour. When making comparisons, please note existing variations in metrics and procedures used during testing.
The timing of air testing, though not proscribed, usually takes place near the end of a project, before final SAP Calculations and an EPC are released.
For residential builds, test results are passed to a SAP assessor who then updates all calculations, validates a pass and issues final reports, and an EPC.
SAP ratings can be significantly impacted by air leakage rates, as serious levels of uncontrolled air leakage reduce a building’s energy performance. SAP Assessors tend to set air permeability targets between 5-10m3/hm2. This is a reasonable expectation, but sometimes this target needs to be lowered for houses hav-ing difficulty meeting their emissions targets. The construction of extremely airtight dwellings sounds like a great idea, but not all dwellings are designed for extremely low levels of ventilation.
Ventilation engineers sometimes assert a ‘maximum’ airtightness of 4-5m3/hm2 as a healthy rate for a natu-rally ventilated house i.e., ventilated only by extractor fans, trickle vents, and windows. Tighter than that would necessitate forced ventilation of some sort.
Some mechanical vent systems feature a heat recovery function (MVHR) whereby heat is extracted from wet rooms and recycled elsewhere in the house.
At Briary Energy, we are experts in helping new build property developers meet building regulations.
Briary Energy happily offer general air leakage design advice and onsite guidance for buildings from the initial planning processes. Post project completion, we provide Nationwide IATS accredited air leakage testing to assist you in demonstrating compliance with building regulations.
As well as excellent expert advice, with our air permeability tests you get:
Official guidelines make clear in which circumstances temporary sealing is permissible. The key contractor is held responsible for any temporary seals in line with ATTMA guidelines. A straightforward method for temporary sealing is to employ low-tack masking tape.
Building Regulations have tightened during the last ten years — a period that has seen design air permeability (DAP) figures go up.
In short, it isn’t easy to determine when a building is in a state of perfect readiness to meet SAP performance figures.
The Risk Of Testing Air Tightness Early
ATTMA (Air Tightness Testing and Measurement Association), recently revealed a seventy percent failure rate in dwelling tests as a direct consequence of calling in testing companies too early. Early testing could end up costing you dearly: there’s the cost of re-testing for a start, not to mention unforeseen person-hours and possible penalty payments for delayed handovers.
You’ll most likely come under pressure to bring the project in on time. And with sub-contractor delays be-yond your control, you may be tempted to ‘just get air leakage testing done and out of the way.’ Don’t be tempted; be professional. And let the seventy percent failure rate statistic in the previous paragraph sound a cautionary note.