Two blocks of ice, two seemingly identical tiny houses standing in the middle of a public thoroughfare. 

The Australian Passive House Association (APHA) in collaboration with the City of Sydney last week unveiled the results from their public installation of the Ice Box Challenge in Martin Place, Sydney CBD, on March 4. The installation was previously showcased in New York, Vancouver, and recently in Glasgow alongside the COP26. 

The premise is that two boxes filled with equal amounts of ice are displayed inside two small houses for public viewing in Martin Place, and the public is invited to guess the rate at which they will melt. One structure is erected to local building regulations, while the other meets the international Passive House Standard, a highly energy efficient building performance standard. 

At the end of the two weeks during the closing ceremony, the amount of ice remaining in each box was measured to demonstrate how well each ice box passively kept out the heat. 

The results? 

The house erected to local building regulations was left with .8 kilograms of ice (from just under a tonne to start with) – in only 12 days, while the Passive House box was left with 413.8 kg of ice remaining. A clear winner – and a stark visual example of the benefits of passive design.

“This is a further opportunity for people to start to fully understand the positive effects to their wellbeing of a healthy and comfortable indoor environment,” chief executive officer of the independent, not-for-profit organisation Paul Wall said. 

“The broader environmental benefits, with lower emissions and reduced running costs, contribute to better outcomes for society and we applaud the City of Sydney for their positive contribution within their own operations and the environmental grants program.”

Almost 35 percent of global energy consumption is currently as a result of the building sector. Better building design, such as the Passive House design, can help to reduce carbon footprint, provide a high level of comfort, and make significant energy savings. 

Passive house principles include glazed windows, mechanical ventilation with heat recovery, quality insulation, airtight construction, and no thermal bridging.

“I was very pleased to be part of this project,” Mayor of Sydney Clover Moore said. “This is a really interesting example of what Passive House means, and to promote passive house design and construction.” 

She said that governments should be more proactive in using their regulatory powers to promote “clear and proven technologies and methods that will help alleviate the climate crisis while promoting a better quality of life for Australians.” 

“The IPCC issued it’s latest report warning that 40 per cent of the world is now in danger zone, species are dying out and even 1.5 degrees warming means that we’re in trouble. We’re experiencing these floods, and probably next summer we’ll experience more.” 

“It is obvious that we need to do so much more – and this is such a great example. The majority of us live in cities, and this would make a real difference.”

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