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The New Part L Building Regulations


What is part L

Part L is a building regulation that concerns construction projects that are new or result in the change of use of a dwelling or all other buildings in England. It sets out the standards for energy performance and carbon emissions of new existing buildings.

What is new

The New Part L building regulation sets out new energy and carbon emission standards for non-domestic and domestic buildings. The recent updates to Part L of the building regulations include a mandatory 30% cut in carbon for all new homes and a 27% cut for all other buildings. The new rules will come into force in June 2022 and there will be a one year transition period for projects that are currently in planning.

Non-domestic buildings

Non-domestic buildings must have a 27% improvement in CO2 reduction which is a 5% improvement compared with the 2013 standards. The changes to Part L include a new principal performance metric measuring energy efficiency. Compliance with Part L will be determined by CO2 metrics and the primary energy use. The primary energy calculations will include account factors like the efficiency of buildings heating systems; power station efficiency for electricity, and the energy used to produce fuel and deliver it to the building.

The new part L standard is bringing in new efficiency standards for new and replacement thermal elements, windows and doors. Key updates are a decrease in wall U values from 0.35W/m2 K to 0.26W/m2 K, and most new windows and curtaining walling U values minimum standard is 1.6 compared to 2.2 previously.

The updates to part L will require an increase in lighting efficiency to 95 luminaire lumens per circuit watt for general lighting for all lighting installations in new non-domestic reporting. All new domestic buildings under the new Part L will need a building automation and control system if they include a heating or air-conditioning system of 180kW.

Domestic buildings

Domestic properties will have to have a 30% reduction in C02 emissions. The cut in C02 will be accompanied by new fabric materials efficiency required for thermal elements of buildings, this will improve the U values of walls from 0.28W/m2 to 0.18W/m2 for windows, roof lights and doors will need to have a minimum U value of 1.4. Additionally, for extensions to existing properties must comply with the SAP method for compliance for metrics of fabric energy efficiency and primary energy. According to the government, this will ensure that 'direct electric heating systems are not used in unsuitable circumstances resulting in high bills for householders.

For both domestic and non-domestic properties wet space heating systems must be designed to operate with a maximum flow temperature of 55°C.

If you would like to find out more about the New Part L Building Regulations please click on this link:



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