England & Wales Building Regulations: Part L1A: Conservation of fuel and power: New dwellings - A summary of the requirements (Version 3)

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Approved Document L1A seeks to conserve the amount of energy used in new dwellings as a result of their day-to-day usage. It achieves this by addressing all the key issues which affect fuel usage throughout the seasons (including cooling in hot summer periods).

This Construction Briefing gives an overview of the requirements for Part L1A (which comes into effect in October 2010).

This sheet gives readers a rundown of the more significant factors which affect energy consumption (such as the effect of solar gain), a guide on how a building's carbon emissions are calculated, and a tabularised list of the five criteria which must be achieved to comply with Part L1a of the Building Regulations.


  • Factors which affect energy consumption
  • The five criteria in Part L1A
  • Calculating carbon emissions
  • Building performance consistent with DER
    • General
    • Party walls
    • Air tightness testing
    • Thermal bridging and Accredited Construction Details (ACDs)

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