The argument between the factions is timely: regulations are being tightened in one direction, as design planning panels pull in the other. Let’s take each idea in turn.

Passive (solar) house (design)

A worldwide phenomenon after WW2, in Australia it was started gloriously with Walter Bunning’s Homes in the Sun book of 1945. The basic idea for cool temperate climates was a highly insulated home, with thermal mass, glazing oriented to the north for winter sun, and better eaves and pergolas to keep out summer heat.

Largely researched at the University of Melbourne, led by Alan Coldicutt, together with the CSIRO Division of Mechanical Engineering at Highett, whose early computer simulations evolved into NatHERS. The research chased idealised thermal comfort, as indicated in heat loss paths for winter and heat gain in summer.

The ideas were championed through examples of solar houses in 1970s’ books: all detached family homes in suburbia, with large areas of inevitably single glazing oriented to the north, hoping to heat up a concrete slab or internal thermal mass. By now, there was little evidence on either physics or social consequences, and the science effectively died.

Conversely, research by Terry Williamson at the University of Adelaide showed how home improvements, such as better insulation, higher thermal mass, better glazing and control of air infiltration, actually led to higher energy use. Most traditional houses were so extremely cold; any improvements led to better thermal comfort, not energy or money savings.

Solar passive was an improvement for the worst-performing climate-adapted houses in the world, mostly through insulation and thermal mass, less through the main feature of passive solar. Particularly ironic in Melbourne, the centre of research, where it turned out there was insufficient sun to offset the heat loss through the single glazing, even if there was a willing housewife to close the curtains at 4.30 in the afternoon.

So little science and research actually supports the arguments made over 80 years. Insulation, glazing and thermal mass are supported, but the central idea of solar having an energy impact should be totally discredited by now. Proponents inevitably fall back on their own personal experience for explication, and it was on the night. Climate science botched.

Passivhaus

This idea is a house so well insulated and airtight that the thermal comfort of the interior can be controlled by a small mechanical system with air changes as low as 0.6 per hour to deliver heating or cooling at constant temperatures. Developed in northern Europe, it suits cold climates admirably well.

This seems odd in benign Australia, as it denies the possibilities of a house related to the outdoors in propitious weather, a long Australian tradition, but advocates allow that the house windows and doors can be opened up in the usual way. They certainly achieve a quality of internal lifestyle. But its hermetic qualities create resistance amongst its detractors.

Proponents champion the huge amount of data and evidence that makes it science-based, the exactitude of internal temperature and humidity it can achieve, and the health benefits that follow.

Passive vs Passivhaus = both/and

With one exception, the arguments were so poorly moderated and presented that the quick conclusion you could draw was that both approaches were fatally flawed. BUT what if we assume the opposite? What if both ideas have their place, or rather, their site-specific appropriateness?

Passive solar is superb for personal winter warmth in the sun, even if it doesn’t save megajoules. Cross ventilation is wonderful in humid summers – achieved with certainty with a ceiling fan, rather than the clumsy fumbling with opposite windows (in houses or apartments). Disclosure: Almost every one of the hundred or so built houses I have designed uses passive house principles, primarily for the comfort sensation, not the savings.

In Australia, Passivhaus is perfect where the location requires a well-sealed building, such as apartment buildings and houses in close quarters. Such as on a busy road, near a noisy pub, or under an airport flight path. Disclosure: I've used this system for a co-living apartment block that has all three of those conditions.

What about the houses already built?

Surprisingly, only about 50,000 certified Passivhaus homes have been built worldwide, leading me to a huge question hanging.

Australia has 11 million dwellings. Almost all the worst climate-adapted houses in the world. Building a few extra passive/Passiv houses will do nothing to cure that. The issue is how to fix houses we have already built, shocking in terms of their thermal performance.

Only one speaker, Jenny Edwards, from Light House Science and Architecture in Canberra, addressed this issue. Her business now only does consultancy work on home improvements after the associated architectural practice closed to concentrate on consulting. Her work is at the absolute centre of where we should all be in this debate.

Being in Canberra gives her an enormous portfolio to work with. House designs copied and transferred from warmer climates to Canberra’s bitter cold (and hot-arid summers) give a thermally miserable city.

It’s the worst: brick 'veneerial disease'; with inadequate eaves and arbitrary orientations to the NCDC's obsession with curved roads and appalling insulation levels, not to mention Mr Fluffy’s asbestos. Plenty to work with, and this is where we need to direct our arguments in future.

Where to now?

We need a programme to improve the majority of Australia's houses. Two key areas. The average project home is woeful in thermal performance. A key contributor over 80 years to the rubbish we now have. Someone needs to combine the principles of passive solar and Passivhaus for project homes and retrofits.

As for the arguments presented by both sides on the night, it seemed akin to counting the number of angels on the head of a pin. A plague upon their designer houses.

Cross-Sections are Friday musings from Tone Wheeler, formerly of Tone on Tuesday. Amateurs draw plans, professionals draw sections – never at cross purposes

Tone Wheeler

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