Latest Aircrete Information

New 2010 Part L Thermal Bridging – Using Aircrete Will Continue To Reduce Heat Losses By Half

A recently commissioned study by the Aircrete Products Association (APA) has demonstrated that aircrete will continue to give half the heat loss of aggregate blocks and timber frame constructions under the new 2010 Part L Regulations.

The BRE, who undertook the work for the APA, analysed specific junctions by substituting aircrete for the aggregate masonry assumed for the Accredited Construction Details (ACDs). The results showed that the reduced “y” of 0.04 can be easily achieved without having to resort to the Enhanced Detailing required of other forms of construction.

Effective from October 2010, the new Part L of the Building Regulations will alter the way in which heat losses at junctions (ie thermal bridges) are calculated and make these losses more significant.

The study shows that Aircrete will continue to offer an advantage over heavy weight masonry and lightweight framing systems, by reducing the amount of heat loss at these critical junctions by half, whilst not having to rely on Enhanced Detailing.

Under current 2006 Regulations, using SAP2005, additional heat losses at thermal bridges are calculated by applying a global “y” value. This is taken as 0.08 where Accredited Constructions Details are adopted or 0.04 if Enhanced Construction Details (increased insulation at junctions) are used. The effect of the reduced “y” is a significant reduction of CO2 emissions (a saving which is equivalent to reducing the U-values of every external element by 0.04W/M2K). Alternatively, the designer has the flexibility to opt for more cost effective constructions with higher U-values whist maintaining CO2 emissions.

From October 2010 any new Building Regulation applications must include individual heat loss calculations for all junctions, using SAP 2009. The previous simplified global “y” approach will be substituted by a specific “y” value, which must be calculated for each dwelling, based on house type.

The APA details assessed by BRE for the 2010 Part L give individual heat loss values for each junction, enabling the improved performance to be taken into account using the new approach, whichmeans Aircrete can continue to provide more cost effective and simple junction details under the new regulations. Under these new regulations Aircrete will continue to give half the heat loss at 0.04 using standard construction details, without needing to resort to the Enhanced Construction Details, which are necessary when using aggregate and timber framed product, thereby continuing the advantage it already enjoyed with the 2006 Building Regulations.

The in-depth study is now available from any of the APA members via the members page

For further information, contact Anna Hern or Paul Mauerhoff at Ridgemount PR on 020 8943 9349 or


Aircrete Products Association

Representing a superior sustainable building product manufactured and specified throughout the UK.