Thermal Bridging Easy Win for Cost Effective Part L Compliance

The Draft London Plan’s 10% target improvement over Part 2013 through energy efficiency measures prioritises fabric energy efficiency over low carbon and renewable energy technologies. Thermal bridging is an easy win for both fabric efficiency and CO₂ targets.

Switching from a default strategy to calculated psi-values – a combination of Accredited Construction Details and bespoke psi—value calculations – recently secured Part L compliance for two of our large RC frame residential schemes.

For the first scheme of around 120 apartments we achieved a reduction of 14% over the Part L Target Fabric Energy Efficiency (TFEE) and a 5% reduction in CO₂ emissions. This reduced the overall ‘Zero Carbon’ Homes offset payment.

For the second scheme consisting circa 300 apartments we achieved a 13% reduction over the Part L TFEE and a 19% reduction in CO₂ emissions. The assessment involved psi-value calculations for 10 heat loss junctions on average.

Our Façade Optimisation work for large-scale and smaller residential developments heavily weights thermal bridging as an early consideration for design teams. For standard construction methods the thermal bridging assessment can be a case of verifying that the heat loss from thermal bridges has been effectively minimized. For more complex detailing our advice on how heat loss junctions can be improved results in cost-effective measures being introduced like structural thermal breaks, insulation continuity, avoiding over-engineering of cladding supports.