Why is air pressure testing required to pass building regulations?

Building regulations in the UK require an air pressure test for all new buildings, in order to be compliant. But what is an air pressure test and why is it necessary?

The reason concerns conversation of energy and heat. All new buildings whether they are domestic or commercial, need to ensure their energy performance is at a certain standard.

A building that ‘leaks’ too much energy and heat is inefficient. It will have a higher CO2 footprint and will be expensive to heat. A level of controlled ventilation is fine, however uncontrolled ventilation through leaks can cause problems with condensation and damp, and affect the lifetime of the property. It is therefore in everyone’s interest to check the energy performance of all new buildings, to see if they meet the building regulation standard. These will have a better environmental rating.

The specific standards are Part L1A and L2A (England & Wales), Section 6 (Scotland) or Part F1 (Northern Ireland) of The Building Regulations. Calculations such as Standard Assessment Procedure (SAP) calculations or Simplified Building Energy Model (SBEM) should be looked at during the design stage, and then they can be verified once the build is complete.

This is where the air pressure test comes in. Air pressure tests are used to test ‘air permeability’ or ‘air leakage’ of a building. This is a straightforward way to verify whether the building meets the building regulation standards.

The first stage of an air pressure test is to consider the scale drawings of the building. Next, the building should be prepared by opening internal doors, and sealing off any ventilation sources such as chimneys or windows. A fan is then installed to draw air out of the property, creating a pressure differential. Various measurements both environmental and within the property are taken, and these are used to calculate the air leakage score.

Some people may be concerned that creating the air pressure differential could be dangerous to the building’s structural integrity, or to inhabitants of the building, but this is not true. In reality, the differential created is too small to have any serious effect, and will only be picked up through the specialist equipment used to assess the air leakage.

Overall the test should take about an hour and it is completely safe for people to stay within the building while it is taking place. The only caveat is that they must not leave part way through the test, as opening any external door would compromise the pressure measurements.

An air pressure test will also identify sources of any leaks, which is important if the building fails the test and achieves a score that falls below the Building Regulations standard. An experienced company will be able to go further once the sources are identified by providing consultation on how best to remedy the leak. In most cases a solution can be put in place quickly, resulting in a pass when the building is retested.

Air pressure testing is necessary to ensure not only that a building complies with the building standards, but also that it’s as energy efficient as possible. This will result in a good EPC rating and cheaper energy costs later down the line.

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