At NOVA Acoustics Ltd we provide nationwide Air Tightness Testing through our network of registered engineers. Satisfactory air tightness of new properties became a requirement in England and Wales during 2006, under Part L of the Building Regulations. This aims to reduce carbon emissions through ensuring the energy efficiency of buildings by setting an overall Emission Rate. Air tightness contributes significantly toward the energy efficiency and therefore the Emission rate of buildings, so specific performance requirements have to be met.

Air Tightness Testing is an assessment of the air permeability, tightness or leakage of a building; the higher the level of air tightness the greater the energy efficiency of the building. Building regulations Part L1A regulates all new dwellings and Part L2A regulates non-residential buildings, such as offices. The process of air testing shows the buildings’ performance at retaining conditioned air and the loss of conditioned air through the structure of the building. It also maximises the retention and minimise the loss of conditioned air, as well as maximising the energy used to heat and cool buildings whilst reducing the overall emission rate of a building.

For dwellings the amount of testing is dependent upon the following:

  • Dwelling Type
  • Whether accredited construction details are used

The dwelling types are defined by the type of property – for example, semi-detached or end terrace – as well as the construction method. We will provide you with a schedule of testing based upon the site drawings. The adoption of accredited construction details will have to be verified by your building control officer or an approved inspector. If accredited construction details are used only one type of each dwelling is tested no matter the quantity of units.

If accredited construction details have not been used the following testing applies:

No. Of Units

Units to be tested

1 – 4
1 of each dwelling type

5 – 40
2 of each dwelling type

41 +
5% of units (unless the first 5 units pass)

We require information on construction methods and site plans to identify the variation in dwelling types on your development. We will also need to know the aperture size to ensure the testing equipment can be correctly installed.

Before we come to carry out your air testing we need to ensure the building is complete to be able to achieve the highest performance possible. The following criteria should be followed to provide you with the best chance of passing the air test:

  • The building should be complete
  • All doors and windows must be fully fitted and functional
  • All electric fittings must be installed and functional
  • Gaps within walls and floors must be sealed
  • Bathrooms and kitchens must be fully fitted
  • All mechanical ventilation turned off with grilles sealed
  • Ensure water is present in soil pipes.
  • 240v power must be available on site
  • Access to all rooms is required
  • No works must be taking place in test buildings

If your test fails then there are a number of techniques available to us to accurately find the leakage area. These include:

  • Smoke Testing – we can use smoke pencils to visualise the air flow during testing
  • Depressurisation – we pressurise the building during testing, by reversing the fans we can depressurise the building and find where air is leaking in
  • Thermography – this is done using an infra-red camera to identify hot and cold spots on the surface of the building; this requires a temperature variation and is usually done at night

There are a number of common reasons that the Air Tightness Test fails. We would recommend that particular attention is paid to the following common problem areas:

  • Sealing around windows and doors
  • Proper installation of trickle vents
  • Properly installed loft hatches
  • Sealing of the junction between walls, ceilings and floors
  • Sealing services pipes including heating, water and waste pipes penetrating internal and external walls
  • Sealing of electrical fittings, such as sockets and switches

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