30 March 2012 – Streets heat up our cities by 6-8 degrees. They are the single biggest cause of peak energy demand.  A hot street makes for a hot building which makes airconditioning “necessary” and increases electricity use.

Cool our streets and we cut our energy use both day and night.

The first long term Australian data on the high temperatures being caused in our cities comes from two heat monitoring stations in Chippendale. These were installed due to community demand and are a partnership between the Chippendale community and Sydney City Council.

Research has been carried out into the data produced by the monitoring stations by Mat Faint, a student of Sydney’s University of Technology. Professor Peter Newman’s research project Biophilic Cities paid for one of the temperature monitors, and a PhD student, Matthias Irger, at the University of NSW chose to review the data from that monitor.

Mr Faint’s report reviewed the data up to December 2011.

In April,2010, two heat island monitors were installed in Chippendale: one in the shady confines of the north-south running Buckland St; and one to bask in the heat of Myrtle St, a street that is vulnerable to morning and afternoon sun due to its east-west orientation.

These monitors were installed to measure the difference in ambient temperature between a street where the dark surfaces of the built environment are allowed to bathe in full sunlight for most of the day, and a street insulated by a thick canopy of foliage.

Figure 1: Average temperatures by time of day – period of record: April 2010 – July 2011

Figure 1: Average temperatures by time of day – period of record: April 2010 – July 2011

These monitors became operational in April of 2010, and in the first 15 months of operation, the trends they have exposed are alarming.

The Myrtle St gauge was on average, 3.1°C hotter than the gauge in Buckland St, and this trend was relatively consistent throughout the day and night.

Because of the road’s absorption of the heat in Myrtle St, the ambient temperature there was never allowed to cool enough to match the temperatures in Buckland St.

The canopy of vegetation in Buckland St is what allows it to be a whole 3°C lower than Myrtle Street.

Overshadowing of the road by buildings also keeps the eastern and western sun off the road.

Even in the middle of the day, where both street alignments are exposed to full sun, the temperature difference between both streets remains around the 3.1°C mark which means that it is in fact the vegetation that mostly cools Buckland St, not just the fact that it is a north-south running street.

What does the data mean?

We know that over 9000 Australians are dying (young and old) premature deaths partly due to the heat caused by poorly designed and maintained roads. (1)

And we know that ants are dying out in Perth due to the heat island effect. (2)

Further research being conducted by Mat Faint and myself seeks to answer such questions as:

  • Is it more cost-effective for a building owner, or a local council, or a local community to invest in energy efficient buildings or in a cooler street?
  • What is the impact on biodiversity of a cooler street: does a cooler street grow more food, greater canopy, kill fewer ants, bees birds and insects and cut premature human mortality?  and cause fewer premature human deaths?

Perhaps the biggest question on our minds, however, is this: is all the energy, all the red tape, all the carbon trading debate misdirected?

If, as it seems, the carbon legislation will do nothing to cool our cities from hot roads, and all the sustainability red tape won’t either, should our priorities be changed to ones which cool our cities by cooling our streets?

Let’s be clear about the science and the carbon pollution laws. The new laws will stop future pollution. They don’t take out what’s already in the Earth’s atmosphere and which is driving climate change and adding higher temperatures. They ignore road design.

It’s the problems caused by existing pollution and existing roads which we need to fix, too, not just cut down or stop future pollution. Or hasn’t anyone noticed the weather – that’s coming from existing pollution and urban heat islands – and the research?  This distinction is clear to those who read the UN’s science reports.

An associated question is this; why is the private sector and privately owned land the target of so much red tape when the one third of our cities, our roads, is ignored by governments?

Could our road agencies and the money we spend on roads be better spent so roads heat our cities less?  When is it more cost effective to cool a street than to make a building use less energy?  The research indicates some or much of our building energy use is due to efforts to make the building overcome the heat caused by the roads outside them.

Why is the public sector getting away with doing so much damage, contributing to premature human mortality from heating up our cities from too-hot roads when the private sector is being loaded up with so many rules about making its buildings use less energy?

Cooling a road is a beaut way to create efficient energy demand. The buildings in the Chippendale street that have air that’s always 3 degrees hotter around them pay more for aircon than do the buildings in the other street with trees and 3 degrees cooler air.

Yet Australia, and most of Earth, has no laws requiring councils and governments to build roads so they don’t increase the heat of the city and the heat load on buildings. This is more than a policy or legal vacuum; it’s discrimination and is causing avoidable costs to the private sector who own buildings.

Will future generations have the same level of incredulity about how hot roads and government rules could do so much damage as that which society had after Rachel Carson revealed widespread DDT poison was killing much of what is in the biosphere?

Future Burrs will provide data from our projects to answer these questions.

Better still, Burr has solutions for cooling our streets and our cities which are quick, affordable and “doable” in the next few years.

May the questions be with you and may a Burr cooled street come to where you live as quickly as we can say, “Cool’.

(1) Australian Climate Commission Report 2011; Victorian Coroner’s Report into the Black Friday heatwave

(2) Arthropods on street trees: a food resource for wildlife , Simrath Bhullar and Jonathon Majer, Pacific Conservation Biology Vol 6, 171 – 173; The effect of urbanisation on the ant fauna of the Swan Coastal Plain near Perth, Western Australia, D Majer and K Brown, Journal of the Royal Society of Western Australia Vol 69, Pt 1, 1986, p 13 – 17

Michael Mobbs’ book, Sustainable House, is the best selling account of how to build a sustainable project, what works and doesn’t. The book shows how Sustainable House has recycled more than 1.5 million litres of sewage in a five square metre garden in Sydney’s inner city Chippendale since 1996, uses rainwater for drinking, solar power for energy and provides accommodation for four people for utility costs of less than $300 a year. See also www.sustainablehouse.com.au