Urban density matters – but what does it actually mean?

Shove up: London's Oxford Street, looking crowded. Image: Getty.

In debates about urban density we often find comments about buildings being too tall or not tall enough, about too many people in a neighbourhood or too few, about streets and buildings being overcrowded or empty.

We are told that Melbourne is building at four times the density of Hong Kong, or that density is good and will make us happy.

But as these debates over density in cities continue, what is most often missing is any clear understanding of what people mean when they use the word “density”.

Is it the volume or height of buildings? Or is it the numbers of people? One person’s high density may be another’s sprawl; the same tall building may be experienced as oppressive or exhilarating; a “good crowd” for one can be “overcrowded” for another. One is reminded of Humpty Dumpty’s logic in Through the Looking Glass:

When I use a word it means just what I choose it to mean – neither more nor less.

What such debate most needs is greater density literacy.

Density is a concept borrowed from physics where the meaning is clear – mass divided by volume. Yet when transferred to the city, nothing is so simple.

Are we talking about buildings or people?

First, we need to clarify whether we are talking about concentrations of people or of buildings. If we take population densities first, these are generally measured as residents per hectare based on census data.

But we also need to distinguish between “internal” and “external” densities – the numbers of people in a room or apartment versus those in an urban precinct. If you look at new high-rise housing in the evening, you can find many apartments unoccupied. At the other extreme, internal crowding largely defines a slum. Building density does not mean population density.

Building density does not necessarily mean population density, an example being low-occupancy housing in Melbourne Docklands. Image: Kim Dovey/author provided.

Population densities cannot be based on residents alone, since the numbers of people in a given neighbourhood at a given time include those who work there or are visiting. In a mixed-use neighbourhood, residents may be a small proportion of the population density.

There are also population density rhythms, as people move from place to place throughout the day and week. The same urban precinct can be densely populated during work hours and empty on weekends. Population density is not only the number of residents but fluctuates over time and with functional mix.

And how do you measure building density?

When we shift attention to building densities, we soon encounter some unavoidable jargon. The most common measure of building density is the “floor area ratio” (known variously as FAR, FSI, FSR and plot ratio) – the ratio of floor area to land area. This is the most widely used measure for limiting the bulk of development on any given plot.

However, it does not control the building height, “footprint” (the area occupied by the building) or “coverage” (the proportion of land covered by buildings). Thus it is quite possible to build high-rise low-density (with very low coverage or small footprints) or low-rise high-density (with high coverage or large footprints).

Most high-rise public housing from the 1960s and 70s is roughly the same FAR as the low-rise housing that was demolished to build it.

Building height is not a measure of density, although sometimes the two align. Confusions here abound; press reports (such as here and here) regularly equate FAR with height control.

Areas of different heights but similar building density in Fitzroy, Melbourne. Image: Kim Dovey/Google Earth.

Another common measure of density is dwellings per hectare. This is often used as a means of assessing population and building densities at the same time. But it does neither, unless we know the size of dwellings and of households. Thus dwellings per hectare is a very blunt measure of density, although a useful proxy for comparing housing projects.

Then there is the distinction between gross and net densities. Urban planning controls are focused on the net density on a particular site – yet such measures are of little use in understanding how cities work, because they do not include the public space of streets and parks.

The gross density is always lower than net density and it is the one that matters in debates over urban density. While we might be packed in on a particular site, the street network of a car-based city tends to keep us apart. Net density is not an effective measure of urban density.

As we measure densities of people or buildings at larger scales, we also incorporate water bodies, freeways and unbuildable sites, so the average density diminishes. Where one draws the boundary is a crucial decision in measuring urban density, or in getting the answer one wants.

Even urbanists such as Paul Mees can be guilty of this when using broad metropolitan density measures to advocate for public transport at suburban densities. Elizabeth Farrelly, a vocal proponent of higher density, compares it to the thread-count of luxury sheets (her minimum is 1,000), yet her only measure for urban density is “dwellings per hectare” – whatever the scale, net or gross.

Here we encounter the politics of density literacy and return to the logic of Humpty Dumpty:

The question is which is to be master – that’s all.

There is no single scale at which to measure urban density, but the larger the scale, the lower the density. The best approach is to understand density as multi-scalar: for any location there is an internal density, a net density, a walkable density and a metropolitan density.

High density is no guarantee of urban buzz

Finally, there is the question of streetlife density – of people in public space, of crowds and crowding. Here the complexities multiply. While we can measure the outcomes in pedestrians per minute or per square metre, we are far from understanding the ways in which streetlife is geared to building and population densities.

These connections depend at least on numbers of jobs and visitors, functional mix, car dependency, access networks and walkability. Yet this is where density delivers its greatest benefits in social and economic encounters – what we often call the urban “buzz” or “intensity” – along with disbenefits such as congestion.

Density without intensity in the car-dependent city – in this case, Tampa, Florida. Image: Author provided.

In Australian cities we have become quite good at generating high density without intensity. Think of car-dominated high-rise districts where few people use the street. Yet we also have good inner-city examples of intensity without high density.

For many people, density has become a negative word. Those who want more of it often use other words and phrases: the “compact city”, “urban intensification”, “transit-oriented development” and the “30-minute city”.

This can be useful language but the question of what it means remains. The challenge is to raise the standard of urban density literacy – not to make density mean one thing but, as Alice might put it, to understand the ways it is made to mean so many different things.The Conversation

Kim Dovey is professor of architecture and urban design, and Elek Pafka a research fellow, at the University of Melbourne.

This article was originally published on The Conversation. Read the original article.


Segregated playgrounds are just the start: inequality is built into the fabric of our cities

Yet more luxury flats. Image: Getty.

Developers in London have come under scrutiny for segregating people who live in social or affordable housing from residents who pay market rates. Prominent cases have included children from social housing being blocked from using a playground in a new development, and “poor doors” providing separate entrances for social housing residents.

Of course, segregation has long been a reality in cities around the world. For example, gated communities have been documented in the US cities since the 1970s, while racially segregated urban areas existed in South Africa under apartheid. Research by myself and other academics has shown that urban spaces which divide and exclude society’s poorer or more vulnerable citizens are still expanding rapidly, even replacing public provision of facilities and services – such as parks and playgrounds – in cities around the world.

Gated developments in Gurgaon, India, have created a patchwork of privatised services; elite developments in Hanoi, Vietnam, offer rich residents cleaner air; and luxury condos in Toronto, Canada, displace local residents in favour of foreign investors. An extreme example is the Eko Atlantic project in Nigeria – a private city being built in Lagos, where the majority of other residents face extreme levels of deprivation and poverty.

A commodity, or a right?

Although these developments come with their own unique context and characteristics, they all have one thing in common: they effectively segregate city dwellers. By providing the sorts of facilities and services which would normally be run by public authorities, but reserving them exclusively for certain residents, such developments threaten the wider public’s access to green spaces, decent housing, playgrounds and even safe sewage systems.

Access to basic services, which was once considered to be the right of all citizens, is at risk of becoming a commodity. Privatisation may start with minor services such as the landscaping or upkeep of neighbourhoods: for example, the maintenance of some new-build estates in the UK are being left to developers in return for a service charge. This might seem insignificant, but it introduces an unregulated cost for the residents.

Privatising the provision of municipal services may be seen by some as a way for wealthier residents to enjoy a better standard of living – as in Hanoi. But in the worst cases, it puts in a paywall in front of fundamental services such as sewage disposal – as happened in Gurgaon. In other words, privatisation may start with insignificant services and expand to more fundamental ones, creating greater segregation and inequality in cities.

A divided city

My own research on branded housing projects in Turkey has highlighted the drastic consequences of the gradual expansion of exclusive services and facilities through segregated developments. These private housing developments – known for their extensive use of branding – have sprung up in Istanbul and other Turkish cities over the past two decades, since the government began to favour a more neoliberal approach.

By 2014, there were more than 800 branded housing projects in Istanbul alone. They vary in scale from a single high-rise building to developments aiming to accommodate more than 20,000 residents. Today, this development type can be seen in every city in Turkey, from small towns to the largest metropolitan areas.

The branded housing projects are segregated by design, often featuring a single tower or an enclosing cluster of buildings, as well as walls and fences. They provide an extensive array of services and facilities exclusively for their residents, including parks, playgrounds, sports pitches, health clinics and landscaping.

Making the same services and facilities available within each project effectively prevents interaction between residents and people living outside of their development. What’s more, these projects often exist in neighbourhoods which lack publicly accessible open spaces such as parks and playgrounds.

This is a city-wide problem in Istanbul since the amount of publicly accessible green spaces in Istanbul is as low as 2.2 per cent of the total urban area. In London, 33 per cent of the city’s area is made up of parks and gardens open to the public – which shows the severity of the problem in Istanbul.

These branded housing projects do not feature any affordable units or social housing, so there are no opportunities for less privileged city-dwellers to enjoy vital facilities such as green spaces. This has knock-on effects on excluded residents’ mental and physical health, contributing to greater inequality in these respects, too.

Emerging alternatives

To prevent increasing inequality, exclusion and segregation in cities, fundamental urban services must be maintained or improved and kept in public ownership and made accessible for every city-dweller. There are emerging alternatives that show ways to do this and challenge privatisation policies.

For example, in some cities, local governments have “remunicipalised” key services, bringing them back into public ownership. A report by Dutch think-tank the Transnational Institute identified 235 cases where water supplies were remunicipalised across 37 countries between 2000 and 2015. The water remunicipalisation tracker keeps track of successful examples of remunicipalisation cases around the world, as well as ongoing campaigns.

It is vitally important to keep urban services public and reverse subtle forms or privatisation by focusing on delivering a decent standard of living for all residents. Local authorities need to be committed to this goal – but they must also receive adequate funds from local taxes and central governments. Only then, will quality services be available to all people living in cities.

The Conversation

Bilge Serin, Research Associate, University of Glasgow.

This article is republished from The Conversation under a Creative Commons license. Read the original article.