A guide to Part L of the Building Regulations

Approved document L1 of the Building Regulations places requirements for energy conservation upon domestic buildings. This is split into two distinct primary documents:

Part L1a Conservation of Fuel and Power in New DwellingsPart L1b Conservation of Fuel and Power in Existing Dwellings

These statutory documents give top level detail on English Government requirements, a further second tier document, the Domestic Building Services Compliance Guide, gives detailed guidance for services including specific efficiency requirements for space and water heating. Devolved administrations in Scotland, Wales and Northern Ireland have region specific documents and requirements.

In order to demonstrate compliance an emissions compliance calculation must be carried out using Standard Assessment Procedure (SAP). To comply, the Dwelling Emission Rating (DER) must be equal to or less than the Target Emission Rating (TER), with DER taking into account regulated carbon emissions including space and water heating. Given the relatively challenging overall building compliance targets set in the current 2013 version of Part L the efficiency of heating and hot water equipment is a key specification point which can have a marked impact on the overall DER.

In the case of retrofit and replacement projects, compliance is simpler; however, boiler efficiency has a part to play here as Energy Performance Certificates (EPCs) for dwellings can be improved by using more efficient products.

You can find out more about Part L of the building regulations here.