Peter Skinner is head of applied research and development at Architectus.
Skinner served as chapter councillor of the Australian Institute of Architects from 2003 to 2013 and was state awards jury chair in 2007. He was elected as Queensland president and served as national councillor of the AIA (2010-2011).
Architecture & Design spoke to him about designing green urban spaces, stormwater issues and why affordable housing is a pressing concern.
202020 Vision is a collaborative network of organisations across the public and private sectors working to increase urban green space by 20 per cent by 2020. How do you think Australia is currently dealing with designing green urban spaces?
Valuable mature parklands, boulevards and street plantings in our cities are often a result of the foresight and actions of our forebears, possibly a century ago. While many recent urban design projects demonstrate skillful design of lush, green and shady public spaces, too often these are one-off projects located in the high-profile and well-serviced precincts within our cities.
What issues do you think needs to be addressed?
Unfortunately, in recent decades, the more typical residential suburbs of our cities are being rapidly de-vegetated. Once suburban backyards supported substantial ribbons of gardens, trees and wildlife habitat, with large permeable yards to absorb rainfall and replenish groundwater reserves.
Today, aerial satellite imagery shows the suburbs are hardening rapidly. Valuable land is subdivided into smaller lots or additional dwellings are built over previously open space. Large houses and apartment blocks are replacing small houses with the remnant open space often limited to metre-wide strips around the perimeter of the site. The minimal separation of buildings at rear and side boundaries restricts planting opportunities and further impacts on the opportunities for passive cooling.
Urban Heat Island effects are increasing much faster than global warming, and it is clear that we are directly to blame for the increasing frequency of heat waves by allowing de-vegetation, hardening and drying of our cities. Impermeable roofs, car parks, driveways and paving dominate our private sites, creating rapid runoff and flash flooding in rain events. The hard surfaces limit absorption and recharge of ground water reserves, further drying the city.
How does it compare to what designers are doing in other countries?
In colder climates, or in hotter climates, where buildings are frequently sealed to conserve energy, the loss of open space and building-to-building separation may not seem too problematic, but in the warmer cities of the subtropics it is disastrous. Comfort here is most easily controlled for much of the year by opening windows for ventilation. However, if the open space between buildings is insufficient to protect privacy, residents will choose to close the windows and switch on air-conditioning, further adding to overall environmental heat loads.
How can landscapes be designed to help with stormwater issues?
Traditional planning controls of maximum site coverage and minimum outdoor space provision have been progressively diluted, allowing land owners to build larger footprints and reducing their responsibility for the provision of open space and planting. Municipalities are increasingly called on to to bear the cost of this loss through intensive urban planting and stormwater management within the limited dimensions of the road reserve.
The responsibility for greening our cities should ideally be reconceived as a genuine public-private partnership between landowners and councils. It should not be considered unreasonable to require land owners to take greater responsibility for the provision of deep permeable soil and sufficient open space to support tree growth within their sites, as well as in the road reserve.
The synergies of combining adjacent private back gardens into a larger inter-building landscape zone and integrating front gardens with public street planting are obvious. Wider clearances between buildings will allow greater branch and root spread. Linking private rain gardens to adjacent municipal WSUD works will provide more effective management of stormwater and groundwater for the benefit of the environment.
Besides these issues, what else do you think are some of the most pressing issues for the industry?
At a time when provision of affordable housing is a major concern, there is pressure to relax development restrictions to allow provision of higher housing densities. But without meaningful restriction on site cover, the cheapest way to provide residential floor area is to allow the house to sprawl to the limits of the site and to sacrifice neighborly amenity in pursuit of maximum individual gain.
Without sacrificing allowable gross floor area, open space can be freed at ground level by allowing taller, smaller footprint building forms. We are currently shaping the cities of the future, and a little foresight is needed to ensure our children can continue to co-habit with trees.