What we do

Air Testing

Air leakage is the uncontrolled flow of air through gaps and cracks in the envelope fabric of a building. Do not confuse this with the controlled flow of air by the use of purpose ventilators, trickle vents, mechanical extract for the comfort and safety of the occupants.

Too many air leakage points lead to unnecessary heat loss and discomfort for the occupiers from cold draughts. Because of the increasing need for higher energy efficient buildings and the need to demonstrate this for the future, building legislation has become more controlled over the performance of new dwellings by introducing air tightness testing.

Air testing has been a major part of house building since 1st April 2006 but only now it is becoming more involved and harder to achieve.

The dwelling is tested towards the completion of the construction process to establish any air leakage problems which occur from the dwelling envelope. It does not need to be decorated or carpeted but should be finished to a reasonable standard. The internal areas of the property are worked out and the test results are formed from the total property area or how much air that property holds in comparison to how much air is measured through the UKAS Calibrated Test Equipment. Obviously if there is more air gas measured through the equipment than the property can hold, the chances are you may have a leak.

The minimum air leakage target value is 10 as acceptable by Building Control bodies but the value used to complete the SAP calculations may be lower; this meaning the lower figure would need to be achieved.

Very few properties dramatically fail the test. Most properties that fail do so within a minimal margin. If the property fails we will be able to investigate the main problem areas and be able to provide advice and guidance on how to rectify the problem properly. A retest will be done after any remedial works but if a problem cannot be fixed or sorted out, the test will need to be re-booked for another day.


New Properties

In order to gain satisfactory approval for Building Regulation Part L1A you will probably be required to undergo an air tightness test to comply.

Regulations have been updated from 2006 to the 2010 Part L1A Building Regulation which sees the Regulations reducing the allowances for achievable air tightness results.

This is worked out by taking the internal surface area of the property and by using the UKAS Calibrated equipment. We can determine how much air is pulled through the fan unit in relation to how much air the property holds. If more air goes through the fan than the property holds, you have a leak. The extent of the leak is determined on the outcome of the test which is told on site.

If there is a leak, this is not a problem; our specialist technicians will locate any leaks and give you advice on any remedial works required and then we retest – simple. All prominent gaps and cracks can be found, rectified or amended to achieve the requested air permeability rating as found in the SAP calculations. Remember we provide you with a service to make sure you get the results you need.


Existing Properties

Testing existing properties is not mandatory from any UK governing body but does give homeowners peace of mind, especially during Winter months when ice cold draughts start occupying habitable rooms.

In the same way as testing new properties, we look for gaps and cracks within the fabric of the building that can cause any draughts and more importantly discomfort in your own home. This also leads to a large amount of heat loss by the heat produced from your boiler not being contained within your house and escaping through the gaps and cracks, therefore making your boiler work twice as hard and using twice as much fuel to compensate.

LF Building Efficiency are pleased to offer this service in which our specialist technicians can come and identify any leakage points and provide a written report. This collates the information found and gives guidance on any remedial work that would help.


Standard Assessment Procedure (SAP) & Energy Performance Certificate (EPC)


All new dwellings require a Standard Assessment Procedure or SAP as it is formally known. It is the Government approved method of assessing the energy performance of new dwellings in order to demonstrate compliance with Part L of the Building Regulations.

The SAP calculation measures the CO2 emissions and energy performance/efficiency of a residential unit. The results produce an energy performance certificate which, along with the SAP calculations, are mandatory on all new build residential.

From October 1st 2010 the new SAP 2009 Methodology will become the standard calculation to measure all new build residential developments, to work in tandem with the new 2010 Building Regulations Part L. As part of the new 2010 Building Regulation changes, SAP calculations will continue to be required for every new dwelling or conversion to achieve more efficient results. The design stage of the SAP submission are to be lodged prior to commencing any work on site.



An Energy Performance Certificate or EPC is a certificate which provides data to show the energy rating of a building. This is produced by using the SAP Methodology, by an On Construction Domestic Energy Assessor.

Any new dwellings either newly built, or by conversion methods or by change of use, are required to have a SAP assessment carried out, which after that is completed produces an EPC outlining the efficiency of the dwelling.

Any existing dwellings will require an EPC if the dwelling is either sold, rented or built. The EPC’s have been created to help improve the energy efficiency in dwellings, in much the same way as they are shown for new build dwellings. This gives the building owner a very good idea how efficient the dwelling is.


Water Efficiency Calculations

Building Regulation requirements G2 stipulates that a reasonable provision must be adopted when the installation of fittings and fixed appliances must now provide water efficient methods to prevent over- consumption of water.

Building Regulation 17K requires that the proposed consumption of the water by persons occupying the dwelling, from new build or conversion construction routes, must not exceed 125 litres per person per day when calculated with the methodology set out in the Communities and Local Government documentation – The Water Efficiency Calculator for new dwellings.

We can help and provide guidance with regard to water efficiency. Fill in our online form and send back with a copy of Floor Plans and we will do the rest.