Part L of The Building Regulation stipulates that new commercial buildings must undergo commercial air testing. The testing validates the fact that the building reduces heat losses and minimises CO2 emissions. It is important for builders to design buildings that will pass the test at the first attempt. In order to do so it is for builders to take steps at the design stage to minimise air leakage and improve resistance of building envelope to infiltration when ventilators are closed. The reference test level is 50 Pacals and design as well as implementation should ensure a result in the region of 4-5m3/hm2. The benchmark may vary depending on whether the building is naturally ventilated or mechanically ventilated and other factors. Design and implementation for air tightness must be based on understanding of Part L of the Building Regulations. 

 

 

Key criteria

 

Part L2B specifically pertains to non-dwelling units whose design and construction must conform to key criteria: 

  • The building emission rate or BEF should not exceed the target emission rate measured in KgCO2/sq. mtrs. per year. 
  • Design should control heating of interiors by solar radiation
  • Fixed building services are required to be within defined limits of standard of energy efficiency. This will include compromises in design dictated by practicality and costs. 
  • Builder should design for limiting building fabric parameters. 

 

The builder is responsible for design stage calculation and state specifications that must be submitted to the Building Control Body. Once the building is complete a report should be submitted to the Building Control Body stating the dwelling emission rate, target emission rate and building emission rate. The calculations should follow the National Calculation Method using approved simulation software. As can be seen the issue becomes complex if the builder aims for a successful commercial air test of the building. The building designer and builder must be aware of defined parameters of floor insulation, lighting energy, building energy model and other details to be able to achieve success. It helps to engage experts in commercial air testing at the design stage itself followed by involvement at various stages of construction, particularly the last stages. 

 

How professionals in commercial air testing can help 

 

If the building fails the official air test then it could pose problems for the builder who must then undertake rectification or carry out design changes that can be expensive and time consuming. Engage experts in commercial testing for air tightness and you benefit by proper guidance starting at the design stage and going forward as the construction progresses. Such testing companies help builders or contractors by carrying out pre-tests when the commercial building is nearing completion to make sure such building will stand a good chance of passing the test. You save money, time and effort with an expert like Ashby Energy by your side.