The Government implemented the Energy Performance of Buildings Directive (EPBD) early in 2006. A key requirement of the Directive is that an overall energy rating must be provided for all buildings. In line with the Directive the Government has revised Approved Document L, effective from 6^th April 2006. The aim is to improve the energy efficiency of buildings by at least 20% compared to the 2002 Regulations. Approved Document L is now split into four parts:

· L1A – Work in New Dwellings

· L1B – Work in Existing Dwellings

· L2A – Work in New Buildings other than Dwellings

· L2B – Work in Existing Buildings other than Dwellings

Immediately apparent is that compliance with the Regulations is now purely by an energy rating method – the Elemental and Target U-value methods have been dropped completely.

The level of information contained in the Documents has been reduced considerably compared to the previous Approved Documents L1 and L2. Rather than showing detailed compliance methods, for example, U-value calculations, SAP Calculations, methods of pipe and duct insulation etc the proposed Documents instead refer to ‘2^nd Tier’ documents – these include British Standards, BRE and industry publications and specific Compliance Guides (e.g. the Domestic Heating Compliance Guide).

To demonstrate compliance the rate of carbon dioxide emissions from the proposed building (the BER – Building Emission Rate) should not be greater than a Target Emission Rate (TER) which is determined by a SAP type calculation methodology called the Simplified Building Energy Model (SBEM).  The method allows for considerable design flexibility so to avoid any excessive ‘trade-off’ limits are imposed on the performance of the building fabric and building services.

There is no guidance on insulation levels for new buildings; the following however gives an indication of the elemental U-values that will assist in achieving overall compliance.

Element	U-Value (W/m²K)
Floor	0.20
Wall	0.25
Pitched Roof	0.16
Flat Roof	0.16
Windows, doors & Rooflights	1.90