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Air Tightness Testing - Essex

posted 27 Nov 2013, 05:00 by Unknown user   [ updated 27 Nov 2013, 05:59 ]
So what is Air Tightness Testing?
Air tightness, air leakage or air permeability all refer to the infiltration of cold/hot air into the building and/or the loss of heated/cooAir Tightness Testingled air from inside through gaps, cracks, holes, etc in the building fabric.

The loss or cooling/heating of this ‘conditioned air’ through ‘uncontrolled ventilation’ affects the energy consumption of the building, as additional energy will be required to re-heat or re-cool the air. It also impacts on the comfort levels of the building occupiers.

Why is Air Tightness Testing important?

Air tightness plays a significant role in the energy efficiency of buildings. 

Reasons behind this:

  • a link has been established between carbon emissions and global warming
  • the production of energy emits carbon
  • the built environment contributes about 50% of carbon emissions
  • heated/conditioned air leaking from buildings requires the use of additional energy to maintain temperatures

By limiting the leakage of heated/conditioned air from buildings, it is possible to reduce energy consumption and costs. 

The government has made commitments to reduce carbon emissions through the European Energy Performance of Buildings Directive (EPBD) and the Kyoto Agreement. 

Part L is their method for addressing the conservation of fuel and power in buildings based on their overall ‘Emission Rate’ and as such places performance requirements on air tightness. Performance is proven through site testing of the completed building.

What impact does air tightness have on carbon emission rates calculated using SAP or SBEM?

Air permeability is an important factor in assessing the overall carbon emission of a building via the appropriate calculation methodology:

  • SAP Calculations for dwellings under 450m² floor area – accredited software has been developed to make calculation easier.
  • Simplified Building Energy Model (SBEM) for buildings other than dwellings – software still under development

Before construction:
SAP calculations or SBEM is used to calculate a Target Emission Rate (TER) in advance of starting building work. This is based on a range of factors including orientation, glazing, insulation, heating system/fuel, etc..

The details of the above are entered into the software along with a ‘Design Air Permeability’ (what you hope the building will achieve under testing) which must be under 10m³/(h.m²) @ 50 Pa or 15m³/(h.m²) @ 50Pa if a poorer assumed value can be used.

The TER is effectively the performance the building would have achieved under 2002 regulations, with a 20% improvement factor applied, in line with wider government targets for reducing carbon emissions. 

To achieve the TER, you may need to change the specification of products, orientation of buildings, heating system or commit to achieve air permeability lower than the basic regulatory requirement.

After construction:
The building is then constructed and the specification and configuration of the building may change over the course of the process. The actual details and tested air permeability figure are entered into the software again to give a Dwelling or Building Emission Rate (DER or BER).

The actual DER or BER must be lower or equal to TER.

This is a regulatory requirement under Approved Document L.

Is air tightness testing mandatory?

Yes, buildings need to demonstrate a minimum level of air permeability (10m³/(h.m²)) and in the majority of cases this is done through an on-site, pre-completion test. 

This is not an onerous requirement in itself but the design air permeability for a particular building may need to be lower to achieve the overall carbon emission rate for the building and/or client specification.

One of our consultants will be happy to discuss your Air testing requirements for your development.

All of our air tightness, air pressure and air permeability tests are carried out in accordance with ATTMA TS1 issue 2 to BS EN 13829 method B standards, and all our test engineers are trained and registered members of BINDT.

For FREE advice and to get a fast Air Tightness Testing quote please call us on 01279 873380, email us at