Does greater density create greater sustainability outcomes?

To the outsider (and dare I say, for the insider), most urban planning pivots around the central assumption that greater density creates greater sustainability outcomes. Even without having any urban planning background, this assumption does intuitively make sense because with density you can minimise the amount of land cleared for housing, roads and infrastructure, and furthermore, get greater economies of scale for these and other investments, particularly public transport. Despite this intuitively making sense, after attending a number of recent forums and conferences, I get the feeling that environmental reasons and not economies of scale are driving the push for greater density.

Interestingly, however, the emphasis may be one-sided because despite the numerous planning guides limiting land release and promoting density, according to the Australian Bureau of Statistics (ABS) “… current homes (have) more bedrooms on average than homes ten years ago. At the same time, households are getting smaller on average with decreasing proportions of couple families with children and increasing couple only and lone person households.”

Other data doesn’t necessarily support the density assumption either. According to research conducted by the Australian Conservation Foundation (ACF) in conjunction with the University of NSW, suburbs that typically have a higher density of population are actually less sustainable than those suburbs on the fringes of cities. According to Australia’s Consumption Atlas report, “…on average, single-person and small households have greater environmental impacts than larger households… (suburbs) with higher average household size also tend to have markedly lower levels of greenhouse gas pollution per capita, and smaller but still clearly lower levels of water use per capita.” ACF proposes that this is the case because wealth is higher in the inner suburbs and by extension, consumption is also higher. The primary argument of the ACF is that consumption is the key sustainability metric rather than location.

So where does the assumption that greater density produces greater sustainability outcomes emerge from? Especially if we look at some of perverse implications that urban growth boundaries have created.

Restricting land supply on the urban fringes of cities has created the situation where demand is massively outstripping supply. When combined with a prolonged period of economic growth that has provided the type of certainty individuals look for before making significant housing decisions, we now see people making decisions to have children or upgrade their homes (building their castles!). These individuals are then competing for the limited supply of land and what is interesting is that whereas once there may have been a greater sense of caution, currently we are seeing these competing individuals and families taking on greater mortgages and other debt because economic conditions are so good.

This is dangerous territory because while we may have environmental sustainability by virtue of reducing the amount of land cleared for housing, it is arguably at the cost of economic, and in particular social, sustainability outcomes. And while I agree that we should never understate the interconnected nature of the environmental system we live in, it seems that our current planning assumptions are not providing sustainable outcomes.

At the end of the day I think sustainability is a product of design because as the ACF’s research pointed out, the higher environmental impact caused by higher density suburbs is a product of consumption rather than location. If the products being consumed were designed better so that they used less electricity and water, and produced less waste, and likewise if fringes were better designed to take advantage of solar-passive design, used smarter materials (like brick!), and overall made less of an impact, then urban planning and environmental management would require a fundamentally different set of assumptions.

Because unfortunately I think that planners have occasionally lost touch with the very reason they exist, just as environmentalists have forgotten that individuals do have aspirations that are greater than their concern for the environment, and equally as business has forgotten that if there is no stable environment, then they will constantly lose money because of ‘acts of nature’ such as drought, flood, hail, etc etc.

Which brings us back to the question; does density create greater sustainability outcomes? Ironically, I think the planners had it partly right by imposing certain restrictions on developers. These restrictions, in the forms of land releases, environmental impact statements, infrastructure development etc have seen the rise of master planned estates that actually emphasis the benefits of good design. Things like recycled water, renewable power generation, tree planting, river and land regeneration, public transport, schools, and perhaps most importantly, partnerships with local businesses (to ensure jobs and services exist so the community can be self-sufficient) have become increasingly sophisticated and common.

So let’s not throw the baby out with the bath water; perhaps our best bet is to go to these developers and ask them questions about how they could do more of the good things they do, and likewise, what regulations should be in place to stop the ‘cowboys’ giving an entire industry a bad reputation! Because I think its fair assumption that leading developers would like anything which lifted their reputation in the community!