SBS issues warning of knowledge gap on Y-values

SBS issues warning of knowledge gap on Y-values

Sustainable Building Solutions (SBS), part of the Travis Perkins Group, is warning architects and housing developers that a lack of Y-value knowledge is resulting in costly and energy inefficient junctions that are the equivalent of adding a hole the size of a set of French doors into the build.

The 2010 Building Regulations introduced SAP assessments which calculate the efficiency of junctions through Y-values (also known as ‘psi’ values). The SBS team is calling for heightened industry awareness of the cost savings and energy efficiencies that can be achieved by minimising Y-values.

If an architect or developer currently relies on ‘default’ Y-values, SBS believs that the junctions will lose as much heat as having a 3m2 hole in the wall. Having this hole, which, says SBS, is the size of a pair of French doors, will mean reliance on additional levels of insulation and expensive energy saving technologies to pass the SAP assessment.

Paul Joyner, Managing Director of SBS, said: “Not planning for Y-values can be costly. The challenge now being faced is that many builders, architects, and SAP assessors aren’t familiar with Y-values, let alone being able to apply a solution to minimise them.

“If this knowledge gap isn’t filled, 33% of heat loss through junctions will continue to occur on typical dwellings built to 2006 standards. We are recommending that architects and builders use independently modelled drawings to achieve the best possible package of products and solutions.”

SBS offers its own Standard Construction Drawings (SCDs) for new-build and retrofit builds looking to maximize the fabric’s contribution to SAP. The drawings, that have been independently tested and verified by BRE, LABC and the HBF, provide a lower Y-value and therefore cost savings, whilst removing the need for the builder or designer to model their own junctions.

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