Converting Australian Homes into Air-tight Eskies 1

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Tuesday, June 16th, 2015
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Australians could drastically reduce their levels of home energy consumption by adapting European methods of insulating buildings to local climate conditions.

Australian homes subject to extreme temperature conditions could dramatically increase their levels of energy efficiency and indoor comfort by overhauling the way the building envelope is designed and developed.

Jonathan Dalton, director of Viridis Australasia and speaker at the SEE Sustainable Experience 2015, points to profound inadequacies in the conventional, purely insulation-based measures employed for maintaining the indoor temperature levels of Australian homes.

“The old approach to improving indoor temperature is to throw more and more insulation at things – but it’s really doesn’t do much to improve the situation because you’re only addressing part of the problem,” said Dalton to Sourceable.

“Australian homes – even those that are trying to be energy efficient, can be likened to a beer stubby cooler. While they do keep the beer cool at first, if you don’t drink your beer in ten minutes it’ll just start to get warm.

“So the stubby cooler certainly stops it warming up as quickly, but it’s not doing a great job. That analogy really applies to Australian homes – yes we do have insulation in our ceilings and walls, but they’re really not very good at maintaining temperature.”

According to Dalton the upshot of this is a demanding, low-efficiency system of temperature control – particularly during those extreme heights of both the summer and winter seasons.

“In the middle of winter you turn the heater on, which can achieve a comfortable environment, but as soon as you turn the heater off, generally within about half an hour, it’s uncomfortable again,” said Dalton. “Conversely when we’re in the middle of summer you turn the air-conditioning on, even with all your windows shut you’re cycling through to maintain temperature.

“It’s really not a very efficient way of doing things – you’re using a lot of energy to maintain consistent temperature.”

Instead of making homes beer stubby coolers, Dalton advocates converting them into air-tight “eskies,” following the lead of measures already adopted in Europe to deal with a different set of climate conditions.

“Basically what we’ve seen in Europe is people treating their homes like eskies, where they always have their windows shut when they’re inside as though the home were a nice, tight esky.” said Dalton.

“While that works fine in the Europe, because when people are in their houses they want to be cosy and comfortable, the exact same approach won’t work in Australia because people like to have that connection to the outside.

“There are still some principles associated with it that approach we can apply here, however.”

Central to the approach advocated by Dalton is the use of vapour barriers that are capable of stopping air from moving in or out, while still permitting the transmission of modest amounts of moisture.

“With our approach of trying to turn our houses into eskies, we insulate the walls, we put the vapour barrier in place to control air movement, and we make sure our windows are shaded so we can stop the sun coming in and heating the buildings up in summer.

“The last part is actually sealing them air-tight – that’s something that’s against the grain in Australia, because we’ve always wanted to be connected to the outdoors.”

While this approach may appear contrary to traditional Australian sensibilities when it comes to their homes, Dalton points to the huge advantages that it presents in the area of energy efficiency.

“The net effect of all this is that instead of needing four of five 10KW air conditioning units distributed around the house, we only need to have a single 1 or 2KW unit in a central area.

“This depends on heat exchange systems, where we have a small amount of air trickling into all the rooms all the time, allowing air to be circulated everywhere.

“So even if your air-conditioning system is in the lounge room, that air will eventually move through and get to the bedroom, so that the whole house achieve a single stable temperature.”

This drastic reduction in the energy needs of home temperature control means that it becomes feasible to transform houses into net-zero or even net positive buildings.

“Just from a energy perspective it means we can cool the whole home using just a solar power system on the roof – just several kilowatts is all that’s required.”

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  1. Peter Hickson

    Jonathan, Surely you are describing the current approach that has been advocated here since 2003, prescribed in the NCC and supported by NatHERS. The sealed and insulated "Esky" designed to minimise losses from heating and cooling. As a result of this approach Europe has issues with indoor air quality, decay building elements and cooling loads are becoming the concern. Since advocating the"Esky"approach, NZ and Australia have inherited the exact same problems. Perhaps a better way forward achieves natural conditioning by using mass-linked ventilation, appropriate climate responsive design principles to achieve adaptive comfort. This approach achieves energy efficiency, sensible adaptive comfort but more importantly it maintains minimum (to maximum) air changes and connection with the outdoors which is as you say is central to Australian lifestyle. Using these same principles that were once advocated by the CSIRO and all levels of government my mudbrick home has been carbon neutral in heating and cooling for the past 23 years. Best practice looks to maximise gains not minimise losses. Glass, Mass, Insulation and appropriate climate responsive design are essential elements.