Part L 2006 ushers in energy ratings but not conservatories

The Amendment to Building Regulations and Approved Inspectors Regulations consists of four new Approved Documents and other related material.

These technical provisions cover the building fabric including windows and doors, plus heating, ventilation and lighting system designs to deliver an overall improvement of 20 per cent to new homes, up to 28% for air conditioned commercial buildings.

Fensa competitors

Fensa is no longer the only installer scheme for self-assessment, being joined by the BSI Kitemark scheme and CERTASS Limited. The main points of the four documents are below. Part L1B is relevant to replacement domestic windows.

Approved Document L1A: Conservation of fuel and power (New dwellings): The elemental and target U-value Method are omitted. There is now only one approach to showing compliance with the energy efficiency requirements.

This addresses five criteria, including:

a. The annual CO2 emission rate of the completed dwelling, as calculated using SAP 2005, must not exceed the target set by reference to a notional building.

b. Building fabric and services performance are within reasonable limits. 2.2 W/m2k is the reasonable limit for the area weighted average U-value for windows, doors and rooflights.

Approved Document L1B: Conservation of fuel and power (Existing dwellings):

Replacements:

Minimum performance for installation of windows, roof windows and rooflights: U value = 2.0 or Window energy rating = Band E or Centre-pane U value = 1.2.

Doors with more than 50% of their internal face area glazed: U = 2.2 or centre-pane U-value = 1.2. Other doors: U= 3.0.

More guidance is given enabling greater flexibility when building extensions including conservatories and other highly glazed designs.

Extensions require a minimum window performance of U value = 1.8 or Window energy rating Band D, although there can be compensation elsewhere in the design.

The exemption for conservatories remains unchanged i.e. conservatories built at ground level and with a floor area no greater than 30m2 are exempt from the Building Regulations (other than having to satisfy the requirements of Part N).

Approved Document L2A: Conservation of fuel and power (New buildings other than dwellings): Considerable design flexibilility, but generally performance no worse than an area weighted average U value of 2.2 for windows, roof windows, rooflights and curtain walling, or 3.3 for a single element.

Approved Document L2B: Conservation of fuel and power (Existing buildings other than dwellings): Generally performance no worse than an area weighted average U value of 2.2 for windows, roof windows, rooflights and curtain walling, or 3.3 for a single element.