Build up or build out? How to tackle urban density

The Sapphire Tower: one of a new generation of residential towers proposed for Cardiff. Image: Nicholas Socrates Associates.

These days, we almost expect that any large-scale, big impact inner-city development will be a skyscraper. But for smaller cities in the UK these proposals can still appear as fairly extreme, and their approval contentious.

Take, for example, Cardiff, where a new 42-storey, 132m high building of affordable student accommodation is due to become Wales' new tallest building. At just under half the height of London’s Shard, the new building seems paltry when compared to the world’s skyscrapers – but developments like this are still big news for smaller cities.

This contention with skyscrapers is something that has been hashed out again and again in cities all over the world. But rather than focus on how high we are building new housing developments, or where they are situated, it is time that we looked at the big picture.

Under pressure

The pressure to accommodate the housing demand in the UK is enormous. However, the opportunity is there to look more at holistic solutions that achieve balanced outcomes. Unlike London, cities such as Cardiff, Manchester, Sheffield and Birmingham, to name a few, are not short of space; they still have capacity to accommodate the housing needed, while promoting happiness and well-being.


Building high rise residential units should be given a great deal of thought, even in those cases when the setting can accommodate them appropriately. There is sufficient scientific evidence of the negative health and social implications of dense living. Nottingham, for example, among other cities, is currently demolishing its iconic towers the Lenton flats, to give way to more positive residential alternatives.

The issue of urban density has been the subject of debate and research for decades, if not centuries. Humans can adapt to their environments but they do so at a cost – and a number of studies have highlighted the links between density and stress as well as other physical and psychological disorders.

High-rise living can be isolating, separating residents from daily urban life and the activities that take place on the streets. Up to three or four storeys, however, one can still comfortably walk down to the street. From a window, one can connect visually and feel part of the public scene. For this reason, many built environment professionals believe four storeys is the maximum acceptable building height to achieve a decent level of connection, protect health and deliver the right level of density at the same time.

Although it may then seem better for our health, low urban density and detached housing in “out of town” locations have been branded as one of the largest causes of greenhouse gases emissions because of car use. Lower densities also make it harder to develop a neighbourhood feeling: they increase travelling distances and may be more detrimental to farming and species preservation due to their potential expansion into agricultural land.

High or low

Despite the perks and pitfalls to both inner-city and low urban density living, people’s preference tends towards the latter. A study conducted in the US found that some people prefer low density suburbs because freestanding houses in open wide areas enhance their self-esteem and sense of ownership, and are convenient for driving and parking. Large UK housing developers have also found that this “American Dream” model also appeals to customers who want “character; neighbourhoods that feel like places with their own attractive identity”.

The major concern over increasing density is the public perception that privacy would be compromised and, although this issue can be resolved with intelligent design, traditional models remain largely the norm. Some aspects of design are essential to achieving a successful density level where people still find peace, a place where they can retreat from the stress of everyday life, a distinctive character, a sense of identity and community belonging.

But which approach should we choose – building up or moving out?

There is still debate about whether humans should live in lower density settlements or if the damage caused to the environment through this approach is simply too large. Unfortunately, both ends of the spectrum – suburbia and high rise – still dominate landscapes. And while people’s preferences justify low density, the argument that higher density better delivers sustainability is often misinterpreted and misused to justify development led by land value and to secure larger economic gains.

Some recent schemes – such as Accordia in Cambridge and Trent Basin in Nottingham Waterside – demonstrate that common ground can be achieved, delivering models of medium density with compact yet green living as a compromise, to create desirable urban environments while also delivering on sustainability.

However, prototypes like these often require innovative and creative funding mechanisms to make schemes feasible; and traditional residential development models are not currently sufficient to cope with all the pressures of the market and legislative frameworks. Until the planning, regulatory and financial mechanisms take the issues of environmental and social sustainability seriously, it is unlikely we will see positive changes in the design and delivery of residential schemes.

Perhaps a bigger effort is required from the built environment industry as a whole to find positive solutions to the issue of housing in UK urban areas. Skyscrapers should be more carefully considered for cities like Cardiff, where medium density developments are still viable and could provide the best of both worlds.The Conversation

Laura Alvarez is a lecturer in architectural technology at Nottingham Trent University.

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

 
 
 
 

Green roofs improve cities – so why don’t all buildings have them?

The green roof at the Kennedy Centre, Washington DC. Image: Getty.

Rooftops covered with grass, vegetable gardens and lush foliage are now a common sight in many cities around the world. More and more private companies and city authorities are investing in green roofs, drawn to their wide-ranging benefits which include savings on energy costs, mitigating the risk from floods, creating habitats for urban wildlife, tackling air pollution and urban heat and even producing food.

A recent report in the UK suggested that the green roof market there is expanding at a rate of 17 per cent each year. The world’s largest rooftop farm will open in Paris in 2020, superseding similar schemes in New York City and Chicago. Stuttgart, in Germany, is thought of as “the green roof capital of Europe”, while Singapore is even installing green roofs on buses.

These increasingly radical urban designs can help cities adapt to the monumental challenges they face, such as access to resources and a lack of green space due to development. But buy-in from city authorities, businesses and other institutions is crucial to ensuring their success – as is research investigating different options to suit the variety of rooftop spaces found in cities.

A growing trend

The UK is relatively new to developing green roofs, and governments and institutions are playing a major role in spreading the practice. London is home to much of the UK’s green roof market, mainly due to forward-thinking policies such as the 2008 London Plan, which paved the way to more than double the area of green roofs in the capital.

Although London has led the way, there are now “living labs” at the Universities of Sheffield and Salford which are helping to establish the precedent elsewhere. The IGNITION project – led by the Greater Manchester Combined Authority – involves the development of a living lab at the University of Salford, with the aim of uncovering ways to convince developers and investors to adopt green roofs.

Ongoing research is showcasing how green roofs can integrate with living walls and sustainable drainage systems on the ground, such as street trees, to better manage water and make the built environment more sustainable.

Research is also demonstrating the social value of green roofs. Doctors are increasingly prescribing time spent gardening outdoors for patients dealiong with anxiety and depression. And research has found that access to even the most basic green spaces can provide a better quality of life for dementia sufferers and help prevent obesity.

An edible roof at Fenway Park, stadium of the Boston Red Sox. Image: Michael Hardman/author provided.

In North America, green roofs have become mainstream, with a wide array of expansive, accessible and food-producing roofs installed in buildings. Again, city leaders and authorities have helped push the movement forward – only recently, San Francisco created a policy requiring new buildings to have green roofs. Toronto has policies dating from the 1990s, encouraging the development of urban farms on rooftops.

These countries also benefit from having newer buildings, which make it easier to install green roofs. Being able to store and distribute water right across the rooftop is crucial to maintaining the plants on any green roof – especially on “edible roofs” which farm fruit and vegetables. And it’s much easier to create this capacity in newer buildings, which can typically hold greater weight, than retro-fit old ones. Having a stronger roof also makes it easier to grow a greater variety of plants, since the soil can be deeper.


The new normal?

For green roofs to become the norm for new developments, there needs to be buy-in from public authorities and private actors. Those responsible for maintaining buildings may have to acquire new skills, such as landscaping, and in some cases volunteers may be needed to help out. Other considerations include installing drainage paths, meeting health and safety requirements and perhaps allowing access for the public, as well as planning restrictions and disruption from regular ativities in and around the buildings during installation.

To convince investors and developers that installing green roofs is worthwhile, economic arguments are still the most important. The term “natural capital” has been developed to explain the economic value of nature; for example, measuring the money saved by installing natural solutions to protect against flood damage, adapt to climate change or help people lead healthier and happier lives.

As the expertise about green roofs grows, official standards have been developed to ensure that they are designed, built and maintained properly, and function well. Improvements in the science and technology underpinning green roof development have also led to new variations on the concept.

For example, “blue roofs” increase the capacity of buildings to hold water over longer periods of time, rather than drain away quickly – crucial in times of heavier rainfall. There are also combinations of green roofs with solar panels, and “brown roofs” which are wilder in nature and maximise biodiversity.

If the trend continues, it could create new jobs and a more vibrant and sustainable local food economy – alongside many other benefits. There are still barriers to overcome, but the evidence so far indicates that green roofs have the potential to transform cities and help them function sustainably long into the future. The success stories need to be studied and replicated elsewhere, to make green, blue, brown and food-producing roofs the norm in cities around the world.

Michael Hardman, Senior Lecturer in Urban Geography, University of Salford and Nick Davies, Research Fellow, University of Salford.

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