A new approach to designing housing in the suburbs could yield much greener housing with smaller footprints and better cross flow ventilation, according to architect Peter Skinner, head of applied research and development at Architectus in Brisbane.
Skinner says a major issue with detached dwellings currently being built in the suburbs is that they take up most of the site, leaving very little provision for open space.
“A more insidious effect is people are no longer planting trees on private property,” he says.
Working with university students, Skinner used aerial imagery to examine the way open space and private greenery is vanishing in Brisbane’s suburbs.
The photographs below show how homes now occupy most of their sites, with rear walls the minimum required three metres from the boundary fence and roof overhangs at the sides almost meeting those of the neighbours.
Having two homes just four to five metres away from each other in this way not only compromises acoustics, it also reduces privacy and the use of natural ventilation, he says.
“With the loss of the side boundaries, people have their curtains drawn.”
In the front of many homes, the garage doors take up a significant amount of space, and any front windows are often kept closed and curtained for privacy as there is little blocking the view in from the street.
“There is very little opportunity to open the house for ventilation,” Skinner says.
“We have turned our back on passive climatic design, and rely on airconditioning.”
Skinner says this can be addressed by returning to pre-vehicle models of housing of two, three, four and five storeys – the types of buildings that are found in areas of walkable density in Asia and Europe.
Skinner has conceptualised a new typology, particularly applicable for middle ring suburbs, that brings together the elements of affordability, environmental performance and the wider urban setting. It is based on an evolution of the classic terrace house model.
He says the use of the terrace house form has an affordability advantage. It can be developed in areas where the existing stock comprises small “austerity era” homes on large blocks, by subdividing the block.
In many Brisbane residential zones, there is a height limit of two storeys. But if developments went to three storeys, the footprint of the house on the site could be reduced, allowing room for greening.
If the 150 square metres of floorspace in a home is spread over three storeys, the building only takes up 50 sq m of the site, he says. On a 150 sq m or 200 sq m lot, this allows for a “decent distance” of open space out the front and out the back, where greening and trees can be planted.
“The other advantage of going up is having privacy at the upper levels. So you can leave windows and doors open for cross-ventilation.”
Creating hard cities
In terms of the broader urban picture, Skinner says we are creating “very hard cities”.
The preponderance of concrete, brick, tile, paving, steel roofing and other hard surfaces and very little opportunity left for deep soil for tree planting on private land means the community increasingly relies on streets trees and water sensitive design principles to keep them alive.
Skinner says the “hardening” of the urban environment also causes increased flash flooding, as there is so little in the way of permeable soil to absorb downpours.
In his design typology, the increased front and rear garden areas enable the site to absorb some rainfall and slow the rate of runoff. It also enables the groundwater to recharge and support trees for shade to prevent urban heat island radiation.
Skinner says the “loss of the backyard” in many contemporary homes also has a social dimension and an impact on energy use. People lose the space for activities like fixing a motorbike, or doing small crafts or gardening. They also increasingly rely on mechanical clothes dryers when there is nowhere to hang laundry outside.
“There’s a lot of relationships with place [in terms of backyards] that people have built up over time,” he says.
“There’s a lot we lose.”
There is also an impact on children, where it becomes harder to have a balanced lifestyle regarding the ratios of exercise outdoors and screen time.
By comparison, terrace gardens can work well for children, particularly smaller ones.
“There’s a lot that comes with space,” Skinner says. “In Australia we really haven’t adapted to apartment living.”
In Europe apartments are designed to accommodate children, and craftwork, but in Australia they are designed mainly for short-term living, Skinner says.
“There’s a big challenge in terms of how much space needs to be provided.”
Challenging the “sacrosanct” suburban house
One of the big barriers he sees to increasing density, even with a terrace housing model, is planning rules. In Brisbane, for example, the “suburban house and garden is sacrosanct”.
“This is very problematic.”
Even small secondary dwellings of one storey in the backyard of an existing home are difficult to get approval for, he says.
The ideal would be to subdivide blocks in key areas, and convert existing blocks with 15m frontages into three terrace strips with 5m frontages and running the depth of the existing lot.
In masterplanning a substantial area of this typology, Skinner says orientation is key for sustainability and passive solar performance.
If the streets run east to west, and the rows of homes are far enough apart, the sun will get into the upper levels in winter, he says.
Skinner has borrowed from the common Sydney and Melbourne inner-urban model of having a wide street at the front and a lane at the rear, and redeveloped the proposition.
Instead of the “mean street” of the lane, the redevelopment would have “green streets” 20m wide at the front of the homes featuring gardens and angled parking, and “lean streets” 13m wide at the rear where the garage door is up against the street.
This would mean every home could have a northerly aspect overlooking a garden, he says.
On both the lean and the green streets, either the shade of trees or shade cast by the terraces themselves provide cooling.
In terms of materials, Skinner says CLT and engineered timber are exciting.
These are very useful in the long-term, he says, and are one of the few materials that sequesters carbon.
In considering their application in the terrace house model, CLT could be used for both the front and rear walls, and for the party wall between houses. It has the fire rating and acoustic properties that make it ideal, Skinner says.
The typology could also be adapted for prefabricated modular components, which would decrease costs and increase the speed and quality of construction.
“I think there will be a change in the nature of our expectations of buildings,” Skinner says.