In any Australian street the temperature of the road surface with sun on it will typically be twice as hot as a road shaded by a tree or building.
The hot road heats up the air where people walk by up to 10 degrees.
Think of streets where you don’t want to stop to shop, to talk, to pause, and which are unpleasant. They’re everywhere, aren’t they?
Businesses have to pay out big for aircon to attract and keep customers who recoil from the road heat battering exposed shopfronts.
Over 30 per cent of our city land is cursed by black, unshaded roads, all designed, built and maintained by local councils who create this avoidable business cost. Councils hold themselves out as the go-to people for what’s right and wrong when we develop our city, don’t they?
These same folk who say we citizens can and can’t do this or that with our privately owned land – because they know best, and demand of us that we have
“sustainable” buildings – are undoing with their black, hot roads the billions of dollars of private investment in passive design, insulation, orientation, materials.
Thank goodness here are two local councils trying to do good in Australian cities, the first of which is NSW’s Canada Bay Council.
A courageous partnership between council staff, elected councillors and businesses is working to support local businesses by cooling Victoria Road in the outer Sydney suburb of Concord. The project focuses on the pavement colour and materials.
The Concord West Sustainable Village Project has recently won the Australian Asphalt Pavement Association’s NSW State and National Awards for Innovation. It recognises “innovation in flexible pavements within Australia”.
Concord West Village on Victoria Avenue runs east west and is always in full sun. To drop the heat the City of Canada Bay partnered with the road building business, Downer EDI, and installed white asphalt to reduce the heat of the pavement and cool the ambient temperature of the village.
The white asphalt cooled the road pavements by 8 degrees and the ambient temperature by 2 degrees.
Mayor Helen McCaffrey said, ”If Councils can keep their local shopping villages cooler then locals will use them more and stay longer. Using local shopping villages is a great way to meet and connect with your neighbours, creating the sense of community and belonging.”
Driving the project are the council’s road engineer John Earls along and Downer EDI’s general manager Gana Varendran.
Additional environmental pavements innovations were applied in Victoria Avenue including the use of Tonerpave asphalt which is made from recycled toner from printer and photocopier cartridges. Previously the residual toner in the cartridges was sent to landfill. Tonerpave asphalt gives this previously wasted toner a beneficial use in asphalt pavements. The toner from 8000 used toner cartridges was recycled in Victoria Avenue which represents 20 per cent of printer and photocopier consumption in Canada Bay. The replaced asphalt was recycled locally to the new St Lukes Park North in Concord
The technical report by John Earls contains compelling data:
“Place activation surveys demonstrated that patronage of the Concord West Shopping Village was predominately affected by ambient temperature. The heat made the Village unbearable so people would stay at home or travel by car to an air conditioned shopping mall.
The white asphalt cools the village and importantly during the outdoor lunch dinning period.
The lunch time period is a key for café patronage and profitability.
Above Graphs 1 and 2 shows that patronage and duration of stay in the village declines markedly above temperatures of 34 Degrees Celsius. Patronage and duration of stay increased after the installation of the white asphalt.”
Once projects such as this produce data, the path becomes easier for industry wide take up. The figures speak for themselves.
The other project gets a mixed report.
A tiny footpath greening project in the Sydney City Council area is significant because it demonstrates the council’s decision to replace black bitumen footpaths with pale concrete, again, with the aim of cooling the city’s roads and adjoining buildings.
Good so far.
But the “greening” is limited to the concrete, not the landscaping, which treats rainwater as a waste product to be diverted away from the plants and trees as fast as possible.
In about 80 metres of footpath works Sydney City Council is:
- Treating rainwater as waste and sending it to pollute the water fish live in
- Diverting over 3 million litres of rainwater each year to Sydney Harbour
- Preventing street trees reaching their natural height and canopy width by denying rainwater to the trees
- Tree, plants denied rainwater by pipe which takes rainwater straight to the gutter then to Sydney Harbour
- Fish, aquatic environment polluted
- Reduced tree canopy and height increases air con use and energy bills in adjoining businesses and residences by over 10% (conservative) (2)
- Reduced biodiversity (fewer birds, insects, less flowering plants, trees) due to higher temperature of soils, road surfaces
- Tree, plants denied rainwater; soil compacts, degrades without water
- Fish, aquatic environment polluted by over 3 million litres each year
- Plants chosen which don’t need water and provide little to no food for insects and birds
Research has found that large, healthy trees remove approximately 70 times more air pollution than smaller healthy trees so that’s a lot of air pollution that’s going to stick around this project. (3)
- Make the roof drains leaky by using agricultural pipe covered with geofabric so water leaks into the soil to irrigate the trees and plants.
- Best practice is to keep rainwater where it falls. Over 70 per cent of rainwater falls gently and is easily absorbed in clay soils; agricultural drainage pipes allow excess water to flow to the street.
- Existing leaky drains installed in 2008 at a cost of less than $300 feed road gardens over 4 million litres of rainwater a year and promote the tree and plant growth in the road gardens.
- Research by Dr John Argue shows clay soils similar to those in Chippendale (typical of Sydney) can absorb rainwater; see pp 168 and 239 of my book, Sustainable Food [Trials showed that infiltration devices (gravel pits, leaky drains, absorption and soak pits) can be used at clay soil sites with relatively high sandstone bedrock with little or no impact on flows downstream]
- Sydney’s Sustainable House, which is nearby, has kept over 2 million litres of stormwater and over 2 million litres of treated sewage on the clay soil site for 20 years and no stormwater leaves the site during intense rainfall of east coast lows.
- Same cost (approximately) as existing pipes
- 10 per cent + savings in energy bills at adjoining properties; increased property values
- Increased biodiversity due to lower temperature of soils, road surfaces
The reason this tiny project matters so much for the health of our cities comes from multiplying the figures.
Say, this design was along one side of six city blocks; the amount of wasted water to pollute Sydney Harbour would exceed 20 million litres a year.
Sydney wide each year this design is what dominates our roads; it wastes over 500 billion litres of rainwater into Sydney Harbour. That’s as much water as is in the harbour.
Within the City of Sydney small projects like these happen constantly. Because they are small, there’s no community discussion. This approach departs from specific goals in the city’s 2030 Vision Plan:
- No consultation = failure to build trust and breach of the building community trust goal of 2030 Vision Plan (“Target 10 By 2030 . . . at least 45 per
cent of people believing people can be trusted”)
- No biodiversity – same ole, same ole boring plants planted in bulk
- No reduction in stormwater pollution (Objectives 2.1, 2.2)
- Lost opportunity for reduction of climate pollution
- Lost opportunity for increase in energy efficiency
It’s terrific to have two inspiring road projects by local government. Hat tip to the two councils.
But it’s no consolation for the destruction of large parts of nine suburbs by the NSW government for a project costing over $17 billion of citizens’ funds for the financial failure that is the Westconnex “freeway” (Enmore, Sydenham, Newtown, Rozelle).
It’s being built with black roads. The forensic research on this black elephant is by Wendy Bacon, here.