What kind of issues to we need to consider when we examine the pluses and minuses of urban environments and livability?  

What about cost of infrastructure, what about ability to grow your own veggies if you want to, what about travel time to work, walkability, privacy?  Urban environments raise multi-variable issues.

At Shaping Suburbia, we understand that there is a call for a careful balance in pretty much all design decisions and there are of course many issues to consider when thinking about places and what makes them what they are.  While some issues to consider point one-way to an answer, others are in direct opposition.


OK, lets look closer at the density of urban environments as a variable and not simply as a choice between the polar opposites of brick-and-tiles housing (sparse) vs high-rise (very dense).  The range of typical issues can be represented by colour (darker green is better).  

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The Sustainability of Density. Source : Shaping Suburbia. 

As represented graphically,  most of the issues can have some 'representation' on the chart by a middle ground of 35-45 net dwellings per hectare.

what about the real world?

But does this theory translate to real world behaviour?  Shaping Suburbia undertook research to look at exactly this issue.  We have shown a link between residential density and the walkability of a place.

The walkability of a place is key determinant of a vibrant, active and healthy suburb as previously discussed in the section Suburbia Now.

Our research looked at physically small 'pockets' (using Australian Beaureau of Statistics' Census Collection Districts) within suburbs over a wide range of disparate areas and assessed their residential density and their walkability.

Highlights from this finding is shown in the graph below showing walkability to residential density in dwellings per hectare (nett). 

Connection between walkability and residential density. Copyright Shaping Suburbia.

You can notice a steep but almost linear relationship rising at low residential densities from zero up to about 25-30 dw/Ha. You would expect this, the more things around to walk to, the more walkable it is. But it is not a linear relationship across the whole range of the built environments density range.  

It does not continue to rise as density increases - instead it plateaus between 70+ and 100. The walkability benefits become maximised.

The residential density of about 45-50 dw/Ha  and beyond is the upper limit of separate titles - in other words residential units cover the right hand 2/3 of this chart.

This leaves a sweetspot of between 35-45 dw/Ha where walkable communities result AND you still have free-hold title family homes. 
Note the 'sweetspot of 35-45 dw/Ha, equates to a population density of approximately 6,500- 8,000 persons per square Km. 


The recent report Sustainable Suburbia by UK architects MJP approached the issue from the carrying capacity of urban infrastructure, such as shops, schools and transport.  

The hypothetical scenarios in the report outlined a range of different urban forms which can realise the required desnity.  Their study pointed to an optimum of 50 dwellings per hectare which is commensurate with the Shaping Suburbias findings.  


Walkability is a key feature of sustainable suburbs.  There are a range of  measures which assess walkability and, via a robust process give it a rating or score.  Walk Score is a US based website that creates a score between 0 and 100 that measures the walkability of any address.  Walk Score measures how easy it is to live a 'car-lite' lifestyle and not how pretty the area is for walking.

The Walk Score algorithm awards points based on the distance to amenities in each category. If an amenity is within 0.4 km, they assign the maximum number of points. The number of points declines as the distance approaches 1.6 kmno points are awarded for amenities further than this. The points are summed and normalized to yield a score from 0100. The number of nearby amenities is the leading predictor of whether people walk.  

If you are thinking that walkability is one thing but walking is another, a recent study looked at precisely this issue and it found that: 

"the examined walkability indices [including walkscore] are highly correlated with walking trips for most non-work trip purposes"
Source : "Validating walkability indices: How do different households respond to the walkability of their neighbourhood?" Manaugh & El-Geneidy

but what about 'good design'?

Yes, its important to have good design.  We are architects - we love good design.  But we also like walkable suburbs, low infrastructure costs per person, a range of shops close to home, great access to social services and to public transport and so on.

Design matters, no doubt. But there is a key point here: these other positive attributes occur and survive best when the density for these things is optimised. The 'sweet-spot' of density allows this to occur. 

Getting the density right is not just about housing more people – it is about creating vibrant, active, safe, more sustainable places where people can live in connected communities and be their healthy best.

a financial model too

Shaping Suburbia has used independent research and 20 years experience with development industry as an integral part of the approach to the solution to improving the sustainability, vibrancy and health of our suburbs.  

Read more about the financial model behind Shaping Suburbia 

will it work?

Studies show that communities designed with active living-friendly design considerations in mind benefit from reduced cars trips, increased walking trips and reduced overall housing costs.
Source : Khattak and Rodriguez 2005 quoted in New Urbanism (Online TDM Encyclopedia).  Litman 2000 and Arigoni 2001 quoted in New Urbanism (Online TDM Encyclopedia).

Improving housing affordability is directly connected with increasing density.  In existing areas this can be effectively achieved by changing lot size.

There are some signs that the ideas outlined in Shaping Suburbia are beginning to take effect.

The NSW government is in the process of creating a State Environmental Planning Policy (SEPP) for Urban renewal. It aims to consolidate and streamline the rezoning process for areas that are defined as urban renewal precincts.

If you would like to look at a practical example of Shaping Suburbia, please click here