With just four years to go until the zero carbon homes policy comes fully into effect, the house-building industry is coming to terms with the challenges of addressing the CO2 performance gap between the designed performance of new homes and what they achieve in practice.
A report published by the NHBC Foundation earlier in 2012 - Low and zero carbon homes: understanding the performance challenge - identified a number of potential causes of this gap, some of which are the ability of building materials and mechanical and electrical systems to perform as well in practice as laboratory testing predicts.
The BBA, together with NHBC Foundation, have recently published the results of an extensive research project using a large-scale rig specially constructed to replicate real life installation of a variety of roof insulation materials.
Supported by the insulation industry, testing was undertaken over a two-year period to establish the effect of air movement on the performance of roof insulation. The findings of this research are outlined in the new report - Air Movement and Thermal Performance.
Among the key findings of the research is that the thermal insulation performance is affected very significantly by air movement, with the U-value of the roof constructions tested increasing by up to 80% at higher wind speeds.
Neil Smith, NHBC Group Research & innovation Manager said, "The NHBC Foundation report published at the beginning of the 2012 helped us to identify a range of potential causes of the CO2 performance gap, but this project has begun to deliver some numbers which helps us to gauge the likely significance of insulation performance, clearly an important aspect.
“Although this project was concerned solely with roofs, it raises the distinct possibility that similar effects would also be encountered with insulation materials used in wall and floor constructions."
