Paper at the International Passivhaus conference explores the role of cavity wall construction in low energy building in the UK
One year on from the completion of the UK’s first cavity wall Passivhaus Green Building Store’s Bill Butcher, project leader on the Denby Dale Passivhaus, is speaking at the International Passivhaus conference in Innsbruck Saturday 28 May 2011 on the subject: ‘Passivhaus & cavity wall construction’. The talk will offer a springboard for the Passivhaus community and the UK construction industry to explore whether cavity wall is fit for purpose to meet high performance standards such as Passivhaus or whether alternative construction methods offer a better route to Passivhaus.
Bill Butcher’s paper will explore the pivotal role of cavity wall construction in the UK – with masonry cavity wall comprising 75% of new housing in 2010. Bill will demonstrate that cavity wall can be adapted to meet the exacting Passivhaus standard and low energy buildings, based on his experience of building the Denby Dale Passivhaus.
Bill Butcher will also go on to explore the historical, economic and pragmatic reasons why cavity wall might have a role in ultra low energy construction in the future, including: familiarity to the UK construction industry, cost and availability of materials, regional planning department requirements; lack of skills/ expertise in alternative construction methods.
Bill will also outline the disadvantages of cavity wall construction at low energy/ Passivhaus performance levels, including:
• Difficulties checking for quality of workmanship particularly on larger projects
• Potential airtightness problems with electrical wiring chased into blockwork of external walls
• Airtightness cannot be tested until plasterwork is complete later than other construction methods and potentially more difficult to rectify
• Thickness of walls adds to building’s footprint
Bill hopes that his talk will open up a debate as to the best direction the UK construction industry needs to go in to achieve demanding sustainability targets: “The UK construction industry needs to urgently embrace Passivhaus low energy design. This will probably require a variety of construction methods. Timber frame or solid masonry construction with external insulated render might offer an easier route to Passivhaus but are less familiar to UK builders. Due to historical and other factors, cavity wall might need to stay in the mix for the foreseeable future. The Denby Dale Passivhaus has proven that it is possible to adapt cavity wall to Passivhaus low energy performance levels. Climate change necessitates ‘better building’ now – using cavity wall to build to Passivhaus levels might be a pragmatic choice at the moment given current costs/ availability of materials and knowhow in the UK. “
For FREE technical resources on cavity wall detailing for low energy and Passivhaus buildings go to: www.denbydalepassivhaus.co.uk
‘Has cavity wall got a future in low energy building projects?’ Bill Butcher’s article for BUILDING looks at other UK Passivhaus projects which have opted for cavity wall construction, since the Denby Dale Passivhaus project.