For Michael Tolhurst, Canberra's record-breaking heatwave last week made it easier to make an important design decision for his new home.
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The Passivhaus Institut-accredited architect decided to include air conditioning as well as solar panels in the plans for the new, energy-efficient project that will replace a Captain Cook Crescent brick cottage.
![Architect Michael Tolhurst is replacing this brick cottage on Captain Cook Crescent, Narrabundah with a Passivhaus home – but he has conceded the need for air conditioning. Photo: Sitthixay Ditthavong Architect Michael Tolhurst is replacing this brick cottage on Captain Cook Crescent, Narrabundah with a Passivhaus home – but he has conceded the need for air conditioning. Photo: Sitthixay Ditthavong](/images/transform/v1/crop/frm/silverstone-ct-migration/cf5cc314-01f4-447f-84e8-e968589a4a6b/r0_0_5472_3648_w1200_h678_fmax.jpg)
"I was sort of hoping that, in principle, I could do something, design something, build something where we didn't rely on air conditioning, and was hoping that the trees in the area provided enough shading," he said.
"Even under the shade of the tree when it's 40 degrees, it's still hot."
Passivhaus, German for "passive house", is a voluntary standard for energy efficiency that relies on extra insulation, high quality windows, no thermal bridges, airtightness and mechanical ventilation with heat recovery to maintain constant inside temperatures in buildings designed for their specific climates.
But in the extreme Canberra climate, where temperatures range from below zero degrees in winter to increasingly regular highs above 40 in summer, air conditioning was a "no-brainer" even in an energy efficient home, Mr Tolhurst said.
"It works really well when you can incorporate some on-site renewable energy technology," he said.
Mr Tolhurst, who is documenting his Passivhaus project in a blog, said if a house was well-built less air conditioning was needed, and with energy and gas prices set to rise, the higher initial cost of a Passivhaus would be balanced out by cheaper running costs in the future.
"Passivhaus provides a way of insuring everyone against the rising price of energy and climate change," he said.
The real application for Passivhaus principles would be in schools and social housing to minimise ongoing energy costs and provide comfort for tenants and building users, Mr Tolhurst said.
"To be honest, free-standing passive houses are not going to change the world, but there is the Australian Passive House Association to roll out this approach to much larger-scale projects," Mr Tolhurst said.
Climate Council acting chief executive Martin Rice said air conditioning was a "double-edged sword" because it saved people's lives by keeping them cool during periods of extreme heat but was also a big contributor to global warming.
Global demand for air conditioners will see numbers increase from 1.6 billion units to 5.6 billion units by 2050, data from the International Energy Agency shows.
"By 2050, air conditioning could use as much energy as China does today," Dr Martin said.
Heatwaves were Australia's deadliest natural hazard, he said, with deaths projected to double over the next 40 years in Australian cities.
But he said solutions were emerging, with energy-efficient air conditioners powered by renewable-energy technology set to help mitigate the effects of prolonged periods of heat with minimal impact on the environment.
The ACT added 22.8 megawatts of photovoltaic capacity last year, with 18.4 megawatts driven by residential solar panel installations, easily the biggest increase in Australia.
Xuemei Bai, a professor of urban environment and human ecology at the Australian National University's Fenner School of Environment and Society, said she sympathised with Mr Tolhurst's decision to install air conditioning.
"I think we should do Passivhaus as much as possible combined with other measures, like solar energy," Professor Bai said.
Cities needed to consider a range of targets when tackling cimate change, including human well-being and biodiversity, she said.
"If we are to successfully battle this climate change war, we have to engage cities and cities just have to take action."
But she said there was still a very important role to play for individuals and consumer decision-making to influence climate change policy.
"Every actor has to play their own role in this," she said.