Wood Window Alliance welcomes Part L guidance

Earlier this month, the Government issued its keenly anticipated guidance documents, following extensive consultation on Part L of the Building Regulations for England and Wales (for the Conservation of Fuel and Power).

The Approved Documents (AD) L1A and L1B provide guidance on a range of measures designed to further improve the levels of energy efficiency and performance in buildings – specifically governing work on new and existing dwellings. The approved guidelines come into force on 1 October 2010.

The Wood Window Alliance (WWA) broadly welcomes the changes made to Part L as it provides tightly defined guidance which is logical in its approach. For instance, for the first time, U-values for windows and doors in new dwellings (shown in AD L1A) are permitted to be calculated in accordance with both BR 443 and the European product standard EN 14351-1. The area-weighted average U-value required has been reduced to be no worse than 2.0 W/m2K.

Guidance for work on existing dwellings (shown in AD L1B) stipulates that for all types of building work, such as replacing windows and doors, building extensions or conversions of existing buildings, windows should have a U-value of no worse than 1.6 W/m2K (currently 2.0 for replacement windows and 1.8 for windows within extensions) or an Energy Rating of band C (currently set at band D or E) or better. Doors should have a U-value no worse than 1.8 W/m2K.

However, where replacement windows are unable to meet these requirements because of a need to maintain the external appearance of the façade or the character of the building, they should meet the centre pane U-value of 1.2 W/m2K, which is unchanged from the current guidance.

The Government’s drive to achieve improved energy efficiency standards over the past few years has featured prominently on its agenda and broadly speaking, the WWA, its members and the wider industry have supported efforts to secure improved carbon efficiency in buildings. Our expectation is that the new Coalition government will continue the drive to improved carbon efficiency.

The Alliance was particularly pleased that the new Approved Document has maintained more than one route to demonstrating compliance – whether through window energy ratings or U-values. Sean Parnaby, Campaign Chairman says: “The Approved Documents are in line with our expectations and we’re pleased that they adopt a reasoned approach that pushes the industry towards meeting tougher targets for energy efficiency. However, it will take some time for window manufacturers to adapt their practices in order to comply.”

As expected, exemptions have been made for some historic buildings and for some conservatories and porches. In these cases, Part L only applies to windows and doors where the whole product is replaced and not repairs, but the guidance does stipulate that compliance in these cases is preferable.

Sean continues: “Overall, the new guidance is a step improvement. We’re pleased to see both whole window and centre-pane U-values have been retained as methods of showing compliance, and the inclusion of the formulae used to determine Window Energy Ratings should make this process more attractive to the manufacturer.

“Offsetting or absorbing any increase in production costs as a consequence of these new regulations is going to be a challenge, in fact the whole fenestration sector is in the same boat. If we are to persuade consumers to pay more, we need to educate them on how they will ultimately benefit from these improvements to the Building Regulations and demonstrate why wood windows remain the best choice for future generations.”