Climate change, globalisation and countless other local factors are driving huge change and innovation in the construction sector.This is great news as new demands are being met and standards raised. However, evolving standards and legislation are creating challenges for specifiers and contractors. In some fields, it’s becoming increasingly difficult for them to gain a clear picture of the compliant options available.
In the rooflight sector, help is at hand via NARM, the National Association of Rooflight manufacturers. NARM is a highly active and influential industry association, committed to providing authoritative, impartial information and support for construction professionals.
One area in which NARM has been particularly active, is helping specifiers to understand the contribution of rooflights to the requirements of Part L of the Building Regulations. In 2006, NARM funded a major research project undertaken by De Montfort University, which fundamentally changed common perceptions about the role of rooflights in the overall energy efficiency of buildings. The report concluded that the use of rooflights at areas up to 20% of the total roof area – will reduce energy use and CO2 emissions and therefore make a major contribution to achieving the targets set in new Part L2A Building Regulations.
The move towards increased rooflight areas places even greater emphasis on insulation values of rooflights. To this end, The Building Regulations require insulation values that necessitate the use of triple skin rooflights.
For all non-domestic applications, the worst acceptable standards for the thermal performance of rooflights in new build work are defined in Building Regulations Approved Document L2A and for all other work in Building Regulations Approved Document L2B.
These documents state that “the rooflight U-value for checking against these limits is that based on the developed area of the rooflight, not the area of the roof aperture.”
However, the true U-value as defined in BR443 is based on the area of the roof aperture and is therefore not the value to which Building Regulations limiting values should be applied.
NARM has published a document which was drafted in conjunction with The Building Regulations, to define the ‘Ud-value’ based on the developed area of the rooflight assembly. It is this value which should be checked against limiting values in The Building Regulations.
The rooflights alone AND rooflight/kerb assemblies must both achieve the required values. The use of double skin rooflights – even on well insulated kerbs – is not permitted.
The NARM document providing guidance on this matter is entitled ‘Thermal assessment of out-of-plane rooflights’.
This issue is just one of a number addressed by NARM over recent months. The association works closely with independent institutions to provide information to support industry professionals. For example, a research project by Oxford Brookes University commissioned by NARM, revealed that rooflights are not a significant contributor to overheating in metal clad buildings.
NARM and its member companies are actively working to support best practice in all aspects of rooflighting, from specification and design to installation and maintenance. Since its formation in 1998, NARM has grown and its membership now includes many of the UK’s leading exponents of rooflighting – in particular, manufacturers including Brett Martin Daylight Systems, Filon Products, Hambleside Danelaw, Lareine Engineering and Xtralite. Associate members and sponsors include Cox Building Products, Kingspan, Roofglaze, The Rooflight Company, Palram and Reichhold.