Andy Sumner, Technical Consultant, BM TRADA Certification, discusses energy ratings and how to achieve them.

BM TRADA Certification was appointed an independent agency by the British Fenestration Rating Council (BFRC) last year and we have enjoyed a steady demand for air leakage testing and computer simulation. Demand is now rapidly accelerating and we are issuing quotes to potential customers on a daily basis. Senator Windows in Ireland has become the first Irish manufacturer to achieve a BFRC rating.

Part of the reason for the surge of demand for energy rating is, without doubt, the imminent changes to Part L, Conservation of Fuel and Power Regulations for England and Wales, which have placed renewed emphasis on fuel conservation. Although the new Approved Document will move away from the elemental method of compliance, the performance of individual components such as windows and doors will be crucial in helping a building to meet the new requirements.

Specifiers will be looking for an effective measure of performance and the BFRC energy rating will give them that. In Ireland, similar forces are at play - new European regulations will mean that from January 2007 all new houses will have to carry an energy rating, which will extend to commercial buildings in January 2008 and to all existing homes a year later.

For manufacturers who have a good track record in producing quality windows, achieving a rating will not be too daunting. The first step is to carry out an air leakage test on the window, in accordance with BS 6375: Part 1 Performance of Windows: Classification for Weathertightness, followed by computer simulation, in accordance with EN 10077-2 Thermal performance of windows, doors and shutters. Calculation of thermal transmittance-numerical method for frames, to determine the energy efficiency of the window. The results from the air tightness test are keyed into the dedicated software programme, along with detailed window profile and glazing information, from which a BFRC Energy Rating is established.

The air leakage testing basically does what is says on the tin! The window is installed into a dedicated sealed weather test rig and is pressurised with air, to strict guidelines within the test standard. The pressure loss from the outside of the window is measured at 50 Pascals wind loading, and the resulting ‘air leakage’ is calculated.

Testing and simulation are offered by our sister company Chiltern Dynamics, the first company in the UK to employ a BFRC-approved simulator. ‘A’ is the top rating, with ‘G’ the lowest. Only four companies to date have achieved an ‘A’ rating, four more a ‘B’. In reality, manufacturers whose windows have scored less than C are working hard to improve the effectiveness of their products by re-design or by using more exotic glazing configurations.

To achieve ‘C’ or above, windows must be well designed, well manufactured and use quality components, including effective weather seals and thermally efficient glazing. It is important for the manufactured window to incorporate well-fitted, good quality weatherseals to the window openings and around the glazing perimeter. Also that the window profiles and associated reinforcements (where applicable) are designed in a manner which provides an effective thermal barrier to the external elements.

The certification process involves creating a detailed specification of the window systems to be incorporated within the BFRC scheme and confirming suitability and compliance of the associated thermal simulation and air leakage test reports. An audit is then conducted at the manufacturer’s premises to ensure the manufactured product relates to the particular technical specifications and that the manufacturer is operating an effective Quality Management System. Upon a satisfactory audit, the manufacturer will receive a unique BM TRADA certificate and the particular window specification is submitted to BFRC for registration. This can only be carried out by an Independent Agency such as BM TRADA. The manufacturer will then undergo regular audits at its premises to ensure continued compliance with both product specification and the general scheme requirements.

The fact that BM TRADA is an independent third-party certification body ensures that both scheme members and their customers have the assurance that windows manufactured under the BFRC scheme, operated by BM TRADA, are regularly audited for conformity and consistency by fully trained, customer-focused auditors.

For more information on:

• BFRC Energy Rating Programme contact Andy Sumner of BM TRADA on 01502 679990 or email .
• Air leakage testing and thermal simulation contact Michael Handley of Chiltern Dynamics on 01494 569824 or email .