Air Tightness

Air Tightness

With more strict building regulations requiring better energy efficiency, air tightness in buildings has become increasingly important in recent years. Architects, Builders and Self Build Home owners are now aware that air tightness, which is the effective eradication of natural leaks and draughts in a home, is the first important step in creating a low energy home. The aim should be to ‘build tight – ventilate right’. Air leakage is quantified as air permeability which is the rate of leakage in or out of the dwelling. It is measured in m3/h/m2 at a reference pressure difference of 50Pa between the inside and outside of the dwelling. In the UK and Ireland the best practice standards for air permeability in dwellings is less than 3 m3/h/m2. A passive house requires an air leakage of less than 1 m3/h/m2. Buildings that are built “airtight” will require some form of mechanical ventilation. Please click here to the Blog Section on our website which discusses the various form of ventilation systems available to home owners when constructing a new home.

When calculating the heat loss for a building, the two elements that have the highest energy loss is air leakage and glazing, as glazing has a higher U-value than the other fabric elements in the home. It is pointless investing a lot of money on triple glazed windows if they are not fitted correctly with air tight tapes and seals to prevent air leakage where they join onto the block. A timber frame home usually comes with an estimated air permeability rating from the supplier whereas it can be harder to achieve a good air tightness rating in block built houses. We always advise our clients to try and source a main contractor who believes in the importance of doing air tightness measures in houses, as this sets the house up to enable the heating system to perform to it’s maximum efficiency. In some instances where air tightness is not high on the agenda for the builder or client initially, we will advise our clients on how to achieve optimum air tightness and conduct air tightness tests as appropriate. The earlier we get involved the more impact we can make to achieving a low energy home. Click here to read more about why you should choose Daly for your project.

Typical air leakage paths in a private dwelling consist of the following:

· Around Window and Door Frames

· Around light fittings and electrical sockets

· At first floor ceiling level

· Where first floor slab meet cavity walls

· Where services such as pipes and cables penetrate the building

Image of Air Tight Membrane fitted to first floor ceiling, and airtight tape sealing ventilation pipe penetrating ceiling
Image of Air Tight Membrane fitted to first floor ceiling, and airtight tape sealing ventilation pipe penetrating ceiling

When undertaking retrofit projects, we will carry out a thermal imaging survey to ensure the building fabric is reasonably well insulated to enable a renewable heating system such as a ground or sir source heat pump to work to it’s maximum potential.

Contact us for more information on Air Tightness

Cost Considerations

Air tightness testing is an absolute must. Failing to conduct air tightness tests at appropriate times throughout your project is like wallpapering over cracks. In other words, you are just storing up problems for the future.

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