AIRAH’s recent Building Physics Forum in Brisbane has highlighted the relationship between thermal comfort, ventilation and occupant wellbeing.
The keynote address was given by Professor Paul Cooper from the Sustainable Buildings Research Centre at the University of Wollongong.
In his presentation “Pushing the envelope: Building physics and improved indoor environments”, Cooper provided an overview of recent developments and efforts to improve the envelope and ventilation performance of buildings, in order to better control the indoor environment.
“Energy efficiency and health go hand-in-hand,” Professor Cooper said.
“And it’s a real issue in Australia. Recent research suggests Australians suffer greater rates of morbidity as a result of cold than people in much colder climates such as Sweden. While this research is in its infancy, the thinking is that this may be due to the poor thermal performance of housing here.”
Challenging the natural ventilation status quo
Pro Clima’s Sean Maxwell presented on the topic of building performance research.
He told The Fifth Estate his presentation was a challenge to the “natural” ventilation people who claim that just by putting a proprietary expensive vent in the wall, occupants are guaranteed clean, comfortable makeup air.
“Well, we spent a few years at Steven Winter Associates in New York trying to challenge this assumption.
“We found that no matter what, commissioning – duct tightness, good duct design and balancing – is important for delivering fresh air to apartments, even if you use the nice trickle vents.”
The reason for this, he says, is that compartmentalisation seals up leakage pathways in an apartment from places you don’t want leakage. It makes possible the pressures that trickle vents rely on.
“Otherwise, it’s wishful thinking.”
We need blower door testing for fire safety
He also made the argument for blower door testing of apartments as a “huge step in the right direction for fire safety, indoor air quality, pest control, sound, comfort and lastly energy efficiency”.
“In-person inspections of fire separations are subjective. A blower door test is quick and cheap evaluation and it gives a number, which is more enforceable than an opinion.”
Mouldy buildings, when it all goes horribly wrong
Attendees were also given insights into what happens when buildings go horribly wrong, for example the mould examples Dr Mark Dewsbury from the University of Tasmania shared during his “not that sciencey stuff, we just build houses” presentation.
As one attendee put it, they were “fun and scary” photos of what happens in many Tasmanian homes due to condensation.
Moisture and its ill-effects were high on the agenda for other speakers too.
Thomas van Raamsdonk from Pro Clima Australia gave a presentation titled: “Time to play with WUFI, hygrothermic modelling for the big dogs.”
WUFI is a suite of software that looks at vapour, moisture and heat flow in both timber and steel buildings. As well as being able to predict the performance of the building envelope and how it will respond to changes in external conditions, it can also give an indication of how at risk the building will be from issues including rot and mould.
Van Raamsdonk told the crowd, “We are reading the history of building science in Germany – the past, the mistakes, the learning stories and the successes.”
In Australia the wish is to skip the mistakes and move straight to the learning and success stories.
“We don’t want to have to go through all those painful lessons.”
The opportunity for Australia, he says, is to learn from the rest of the world.
Brett Beeson from Lehr Consultants shared his own experience of designing and constructing a home. Beeson did the lot – the energy assessment, the air barrier detailing and the air tightness testing post-construction.
He told attendees he learned a lot from the process, including that the next house he builds will use different windows and will achieve better levels of air tightness.
Japan’s sick house syndrome
Andy Russell from Proctor Group highlighted lessons from the “sick house syndrome” experience in Japan.
The issues were caused by poor moisture management in building systems, and the commissioning and testing of buildings.
Russell says the Japanese have gone to “great lengths” since to conquer the problems with building quality.
Why thermal modelling can give the wrong answer
Dr Clyde Anderson from Anderson Energy Efficiency showed how some thermal modelling is giving the wrong answer due to the compression of fibre insulation once installed in commercial buildings.
The stated R-value of many fibre insulation products is compromised when it is installed on top of roof purlins on the underside of a metal roof, he explains.
When the roof is then screwed onto the purlins it compresses the insulation – causing it to lose up to 25 per cent of its R-value.
Other presenters included Inhabit Group engineer Jessica Hogg, Mahmudul Hasan from Certis Energy, Chris Killoran from Arup and AIRAH executive manager – government and external relations Phil Wilkinson.
Wilkinson says that even though the forum is “rather technical in nature”, in the end it’s really all about people.
“By controlling flows across the building envelope we can deliver better indoor and outdoor environmental quality, thereby improving the comfort, wellness and performance of people,” Mr Wilkinson said.