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Introduction to Part L
• The aim is to meet the requirements of The Energy Performance of Buildings Directive (EPBD) which aims to further combat climate change and requires buildings to be better insulated and make use of more efficient heating systems.
• The changes to Part L (conservation of fuel and power) of the Building Regulations for England and Wales are applicable from 6th April 2006.
• The revised part L will also make air leakage pressure testing of buildings mandatory.
• The use of Robust Details for air-tightness of dwellings may provide an alternative to routine testing, although at present the required details have not yet been developed.
Although the performance values of the building envelope will depend on factors such as air permeability values, fuel type and heating efficiency, it is likely that wall
U-values of around 0.30 W/m2K will be required.
Approved Documents
The new Part L Approved Documents are in 4 sections as follows:
Part L requirements – dwellings
The 2006 amendments to Park L1 seek to achieve about a 20% reduction in carbon emissions when compared to dwellings Built to the 2002 standards of thermal insulation. Compliance can only be demonstrated using a revised Government’s Standard Assessment Procedure (SAP 2005) calculation procedure.
SAP 2005 & Emission rates The use of SAP 2005 will result in the reporting of CO2 emissions from:
1 Space and water heating, (CH) and,
2 The use of internal fixed lighting (CL).
The Target Emission Rate (TER) will need to be determined. This is calculated using approved software based on SAP 2005 and is, in turn, based upon a notional building which assumes a 20% improvement on the 2002 regulation design values. The following formula is used to determine the TER.
TER = (CH x fuel factor + CL) x
( 1 – improvement factor)
The fuel factor is a tabulated value from the Approved Document and is dependant on the fuel type.
The dwelling emission rate (DER) is calculated based on the energy features of the proposed dwelling. It needs to be carried out twice.
Part L1 Housing |
Approved Document L1A New dwellings Approved Document L1B Existing dwellings |
Part L2 Non Dwellings |
Approved Document L2A New buildings other than dwellings Approved Document L2B Existing buildings other than dwellings |
First |
based on the 'as designed' constructuin for submissions to Building Control. |
Second |
on completion taking into account the actual construction and service, as well as the actual air permeability found from site tests. Neither value should be worse than the TER for the dwelling to comply. |
A number of other publications are listed in the Approved Documents and are relevant to assess compliance.
Approved Document L1A, L2A & L2B
Energy performance calculation of AD L:
• Sap 2005 for new dwellings up to 450m2 floor area
• SBEM (simplified building energy method), for non-domestic buildings and dwellings over 450m2 floor area
• National calculation method for non-domestic buildings
• Aims to reduce overall consumption as measured by the total annual co” omissions (kg/m2 of gross floor area)
• 20% reduction for acmv buildings (non-domestic)
• 15% reduction for naturally ventilated buildings (non-domestic)
• Also proposal for non-domestic buildings to contribute 10% of their energy from renewable sources, e.g. solar heating, photovoltaics, heat pumps, chp systems, wind generators, wave power etc. (“consequential requirement”)
