Build Tight, Ventilate Right
Guest Blog by delegate John Horth BA RIBA FFB, Director of Horth Architects
“Just got back from The Green Register’s ‘Build Tight, Ventilate Right’ seminar at the Create Centre here in Bristol, with my head still spinning. I don’t know about other architects, but what I look for in a CPD event is an update on latest developments, a bit of technical information/explanation and – possibly the most useful aspect - a guide to sources of information and support on the subject. Well, at this day-long event we got all three in spades.
Green Register director Lucy Pedler kicked off with a round-up of the issues, highlighting the need for better understanding across the industry, especially when it comes to achieving higher standards on site. A whirlwind tour of different construction types and how they performed illustrated the need for improved standards of airtightness - or more correctly ‘reduction of uncontrolled air movement through the building fabric’ – especially with increased levels of insulation. She also touched on breathable construction and a round-up of some of the new wave of ‘green’ envelope materials.
Next up was Niall Crosson of Pro Clima, a company specialising in the nuts and bolts of air sealing. Niall took us very adeptly through some highly technical explanations and illustrations, which was not as dry as it sounds – and as with all the presentations, his was enlivened by the occasional exchange with members of what was clearly a quite knowledgeable and engaged audience.
The morning session was rounded off by Gerry Lennon of Sandwood Design and Build – my personal favourite. Always trust a builder to ‘tell it like it is’. Gerry is clearly passionate about achieving high standards of sustainability and quality – it came as no surprise that The Peabody Trust is amongst his key clients – but he was equally forthright about the realities of working on site. Gerry summed up the ‘heavyweight versus lightweight’ debate as horses for courses and reminded us to stick to the KISS principle. He also flagged up the major problem of the loss of skilled workforce when we do come out of the recession, and how this will affect future detailing and specification.
After lunch, Steve Smith and Craig MacDuff of Passivent covered respectively the domestic and commercial side of ventilation design. The relative merits of MVHR (Mechanical Ventilation Heat Recovery) and PSV (Passive Stack Ventilation) were considered for housing, and mixed mode versus natural ventilation for commercial applications. Again, a good balance was struck between technical information and general awareness raising.
The talks were rounded off by Ray Faulkner of iRed, a thermal imaging specialist. Ray provided a fascinating introduction to this ‘black art’, debunking some of the claims implied for it by the media, as well as illustrating its potential usefulness in pinpointing thermal building defects. He also provided some valuable insight into the pitfalls and rash claims of some practitioners. Certification is on its way.
At the end of the day, we all filed out to the Create Centre’s ‘Eco-House’ - which was built on to the side of Bristol City Council’s sustainability headquarters some ten years ago as an experiment in green house design – to witness an air pressure test in action. Nothing like a live demonstration – it was very revealing to feel air streams coming in from the most unlikely places. Tom Gregory of Chiltern Dynamics, carrying out the test, told us about the most common problems encountered, and pointed out that the maximum leakage level of 10m3/m2hr required by the 2006 Building Regs was not only somewhat undemanding, but was almost risible when compared to the 2m3/m2hr demanded as a maximum by the European Passivhaus standard. But watch out for the 2010 Part L – and the 2013.
After the event, there was an opportunity to witness a further air test with live thermographic imaging at Lucy’s house, which she and husband Paul McWilliams upgraded from a 30s semi with overcaldding, high performance windows and other enhancements. Owing to a prior engagement, I was unable to attend, so also missed the supper at a local Italian beforehand – sociable lot, the Green Register.
Better go now – I’m just off to unscrew a few sockets in my own ‘eco-house’ and check the integrity of that vapour control barrier. Then, I’m not sure who I’ll call in first – the thermal imaging SWOT team, or the airtightness Gapbusters…
For information on Green Register Membership and Courses please call 0117 377 3490. With over 500 members and 8 years of experience in providing sustainable construction training, TGR continues to offer a wide range of CPD opportunities to architects and other industry professionals.
John can be contacted at: john.horth@horth.org.uk, http://www.horth.org.uk/
on 01/01/10
Dear John & green register,
I would be interested to know your thoughts on the need and potential difficulties of applying the build tight ventilate right principle to existing properties, particularly older stock with sub 50 SAP ratings. It seems to me the eaier part is the sealing but retrofit low level ventilation seems a challenge where ducting does not currently exist in terms of disruption, visual impact and possibly cost.
kind regards
keith