Cool Roofs and Earth Tube Air Conditioning in Renew Magazine


Installing earth tubes at Aldo Leopold Center. Photo: from Renew magazine
Dumb Roofs
Renew magazine for Jan - Mar covers a lot of ground in its 106 pages on "technology for a sustainable future." But for me the stand-out article covers a subject dear to my heart. The dumbest idea in Australian architecture - black or dark grey roofs.*

We get a bucketload of sun in this country. Just recently several of our major coastal cities had consecutive days over 40°C (104°F). What are the best colours to attract the hot sun's rays? Black and dark grey. It's madness. We're building houses to be be ovens and solve the problem by whacking in air conditioners, with all their attendant issues of expensive running costs and significant greenhouse gas concentrations.Renew magazine suggests aesthetic considerations might be riding roughshod over energy efficiency. But then offers suggestions on how the issue might be resolved. Such as reflective paint, including some that are now available in dark colours. Apparently the "the particle size of the ceramic/glass/metal additives in the paint are such that they reflect the heat without reflecting visible light..." And some corrugated steel roofing now comes with coatings that don't absorb as much heat as previously.

While the US has its Cool Roof Rating Council and Europe their CoolRoofs Project, Australia with all its scorching sunlight has very little in the equivalent vein. So in true Renew style they propose a Do It Yourself (DIY) option of using a non-contact infrared thermometer to take readings of the hot spots in one's ceiling, to see where ceiling insulation can be improved to reduce heat gain from dark roofs.

Hot Windows
In a related article, Renew looks at heat ingress through windows. They report on a study in the mostly tropical state of Queensland, that investigated if glazing could reduce electricity loads. Queensland, in the top north east corner of Australia, was forecast to have air conditioners in 60% of homes by 2014. But that figure was soon eclipsed with 70% of residences having the wall mounted energy hogs by 2009. Yet, with proper double glazing an energy rated 5 Star home could jump up to a 7 Star house, and reduce energy bills by up to 45%. Low emissivity coated single glazing achieved an 11% saving.

Cool Tubes
Elsewhere in the information packed magazine you'll find stories on earth tube cooling, whereby the chimney stack effect is deployed by having cool air enter a building from massive horizontal concrete pipes buried two metres (6.5 ft) under a dwelling. As hot air rises out high roof vents it draws in the cool air from underground, negating the need for electric air conditioning. Renew looks at the work of Sol Architecture in Australia and the Legacy Centre at the Aldo Leopold Foundation, the highest scoring LEED building in the USA. (see lead photo).

Smart Ideas
You'll also find a smart DIY greywater water system for renters, that they can take with them when they move rental properties.

Another DIY project submitted by a New Zealand reader was for a solar food dryer, that was so inexpensive to make, it paid for itself in under three days.

A DIY remote power supply constructed with the aid of a unwanted uninterruptable power supply (UPS).

An exhaustive buyers guide to just about every photovoltaic solar panel available in Australia.


Off-grid strawbale house for family of five. Photo: Renew magazine

Features on homes made from strawbales, and from mud bricks.

The magzine's parent organisation, Alternative Technology Association (ATA) lists its 16 recommendations to the Victorian state government for resolutely addressing climate change.

A snap shot of the world's ginormous solar plants under construction is balanced with the story of volunteers installing a solar-powered water pump for a tiny village in the remote back blocks of East Timor.


Volunteers install a solar-powered water pump in East Timor. Photo: Renew magazine.

In light of the tragic bushfires in Victoria, Renew magazine evaluates how eco-friendly building materials cope with fire.

And so much more. Alas for our non-Australasian readers Renew magazine is not yet available online, being still a print mag, available at newstands. But it is available by subscription from the Alternative Technology Association.

A fresh new issue will be out at the end of this month. In the meantime there is an online discussion forum for some of articles in the current issue. And a rash of other sustainability forums, as well.

:Renew Magazine
More Renew Magazine
Renew Magazine: Technology for a Sustainable Future
South Africa's New Joule and a Waste Free Year in New Zealand
Show Us Your Best DIY Electric Bicycle

* For the record we bought a house with black tile roof, so my frustration with the concept also stems from first hand experience.

Tags: Books | Education | Energy Efficiency