Building in the green belt: 1

This is a post in two parts. In this first part, I’ll set out some reasons for considering green belt development. In the second part, which will follow (eventually), I’ll describe a test case proposal for a specific green belt site.


People have made good arguments for developing some of London’s green belt as housing. After thinking about this for a bit, I agree. The quantity of land designated as green belt is excessive, given the intense pressure on London’s existing housing and the escalation of house prices. Green belt designation helps to create that pressure and the rise in prices: it is inequitable policy.

I’m not arguing for the abolition of green belt: I think it should be reformed. Not all green belt land is of equal quality. This helps enormously when it comes to considering how some of it could be converted to housing. We are not talking about national parks, or anything much resembling ’nature’. Instead, large tracts of green belt are used as monocultural farmland (leading to the argument that suburban housing, with extensive hedge planting and gardens, delivers better biodiversity). Big chunks are laid out as golf courses. Some green belt is not even green, and of non-existent amenity value: gravel pits, surface car parking.

Still, there are people who believe that the green belt shouldn’t be touched. What are their arguments?

1: Limiting the city

One argument for retaining the green belt is that limiting the city is good in itself: why should the city be allowed to grow indefinitely? This connects with arguments about immigration: why should the population grow indefinitely? Here I think we run into a kind of fallacy where principle is argued against degree. Most would accept that at some point a city, or a region, or a nation, is ‘full’ and should not grow further. The issue is whether or not we’re at that point. I don’t think London is ‘full’. I also don’t think that the very high densities typically now proposed for urban sites are acceptable, or that existing lower density areas can be made denser to a sufficient degree (I will discuss this further below). Therefore, to allow for growth, the green belt constraint on the city should be relaxed. Exactly how far is a matter for further argument, but it’s an argument in which all sides can accept the principle that there should be a limit to growth. Advocates of green belt development are not saying that the city should grow forever, until everything is ‘covered in concrete’. Instead they tend to agree, as I do, that there should be a green belt; just not the green belt that we have.

2: Non-green belt solutions

Another argument accepts that the green belt contributes to the pressure on housing but claims that this pressure can be relieved in other ways. Development of the green belt is therefore unnecessary, at least for now. This is a much better argument. But let’s look at how urban intensification is currently done.

Open market sites

The key fact here is that suitable open market urban sites in London are scarce and expensive. This has led to a very large increase in density in those places where development is happening. The London Plan calls for a maximum residential density, for sites with the best access to public transport, of 1,100 habitable rooms per hectare. A typical modern housing development will tend to exceed this density by a large factor (2,000-3,000 habitable rooms per hectare is not uncommon). This has two consequences. One is height: London is rapidly acquiring towers, or high slab blocks. These are relatively expensive to build and carry significant environmental penalties: poor daylight, wind at street level, and visual impact on the skyline. Another is intense pressure on the amenities that go with housing: child play space, car parking, schools. Partly as a result, developers have aimed this style of development at people without families: that is, occupants who can accept relatively small dwellings, don’t need cars, and don’t call on facilities such as schools or parks.

Non-traditional urban sites

In response to tower proliferation some people have called for moderated density, albeit still an increase, and have looked for alternative urban sites across which non-high rise housing might be distributed. A recent competition organised by New London Architecture threw up a range of ideas. In addition to (the usual?) capsules and houseboats we saw residential schemes that in effect double count land: housing on top of retail car parks, on top of schools and hospitals, on top of railway lines, and in one perverse proposal, instead of roads (refuse collection and fire brigade access to be determined). But the thing to note here is that the principle of mixed use development already informs planning policy in every London borough and has not significantly moderated the cost of land or reduced pressure on housing. Stacking uses is hard. The 2005 Gerrard’s Cross tunnel collapse shows the risk of building over a working railway line. It is almost impossible to imagine building on a working hospital, or even on top of a school. How do you connect services? How do you guarantee un-interruption of existing services? (Hospitals are very highly serviced.) How do you even get to your front door? (Hospitals are secure buildings, and schools require secure sites.) Housing on top of shops is feasible if starting from scratch: this was first seen on a large scale in the 1990s with the development of the Cromwell Road Tesco, and is a feature of the recent Woolwich Central development (and perhaps undeserving winner of the 2014 Carbuncle Cup). Large scale stacked use schemes may have a place but raise liveability questions and are difficult to construct: I don’t foresee them arriving in quantity.

Suburban intensification

More promising is the idea of suburban intensification. Much of suburban London is low density: it is largely under-utilised land. But simply observing that large areas of London are low density is not enough. It is true that, were these areas to be rebuilt at the density of Islington or Chelsea, there would be a large increase in housing stock, and without need for high rise. But these areas cannot easily be rebuilt wholesale: the land is already divided and owned. Hence one line of investigation is to see if existing households could be helped or incentivised to sell, for higher density replacement development. But even taking an optimistic view, land release here is likely to be slow.

Council estate redevelopment

Perhaps most promising of all is redevelopment of low density council estates (and some are low density overall despite inclusion of high rise). This type of redevelopment is already happening in several central London boroughs (I live in the recently redeveloped Myatt’s Field North, Lambeth), and the model could be extended to outer boroughs. It is politically sensitive, and tends to be described as ‘social cleansing’ if existing council homes of similar quantity and quality are not re-provided in the new development. There is a risk that sites that are made available in this way will be unpopular with purchasers, who do not always want council tenant neighbours; this, in turn, pressures developers to reduce or exclude the social housing component. And again the land is not empty, it is built; hence there is sometimes a risk to significant existing architecture, such as Robin Hood Gardens in Poplar, East London, which is to be demolished as part of an estate intensification scheme. This is a conservation issue, which should be weighed against the desire to retain green belt: is it really better to sacrifice a good example of modern housing over even the lowest quality green belt?

Council estate redevelopment at higher density – combined with whatever can be gained from suburban intensification – can help to grow the city while leaving the green belt untouched. But is it enough? And are advocates of this route to growth adopting a balanced, moderate, or fair position? When combined with fastidious preservation of green belt, advocacy of estate redevelopment looks partisan. Advocates of this route only to growing the housing supply are open to the accusation that they favour one constituency, those who enjoy green belt adjacency, over others; those who live in and around council estates, and those who live in suburbs targeted for densification.

3: Escape from urban life

A final argument for leaving the green belt untouched is that it provides essential amenity – an escape from urban life. I agree that some of it does: I spend plenty of my weekend days biking up and down the Surrey lanes popular with cyclists. However, a point made by Howard – the originator of the garden city idea – still stands: the ‘countryside’ is often not accessible. It has open spaces but also ‘no trespassing’ signs. Knowing that much green belt is farmland, this shouldn’t be surprising: farmland is rural industry; someone’s productive resource, not a leisure resource. And then there are the golf courses and country clubs; also typically enclosed, with no right of access. There is also the issue of infrastructural barriers to access: the green space exists, and perhaps you have the right to go there, but can you as a practical matter get there?

Howard answered both of these challenges with one idea: the garden city would enfold the green, developing some as housing and employment and making the rest more accessible than before, both as a matter of right, and physically. Howard is often taken for an advocate of the suburb but he envisaged small, relatively dense and delimited settlements, interspersed with a mix of public parks and farmland, and linked by fast rail connections. Compactness produces practical variety: if you live two hundred meters from a green space, you are likely to be able to go there often. Rail connections give further choice: if you are bored with the settlement where you live, and with its amenity offer, you can quickly travel to another. His emphasis on rail as a key enabling technology is in part down to context – cars existed only as prototypes when he wrote Tomorrow (published 1898) – but increasingly, rail – efficient, sustainable – is vindicated as the transport mode of choice. But new rail links are only justified when they serve development. Counter-intuitively, development – by bringing the railway – helps with the escape from urban life.


There is huge demand for housing in London. Although the green belt brings certain benefits – principally leisure – through restricting supply it also harms. As it stands, green belt legislation is bad policy. It preserves open land of questionable quality. It preserves land that is often hard to access, undermining the claim that what is being preserved contributes to London’s amenity. Efforts to find non-green belt sites for increasing housing supply not only risk falling short, they risk leading to extremes, such as planning to redevelop most of London’s council estates. That we are contemplating such extreme measures only highlights the unfairness of the institution of the green belt. It deserves reform.

Danish density

Following the last post, I thought I should try to get some data on housing density in Copenhagen, which is widely taken as a model for urban development. From this paper by Jin Xue at Aalborg, I get a figure for habitable space in Copenhagen of 51 m2 per person. Interestingly, this is at a population density of 27.7 pers. / ha, which is relatively low. There’s further interesting commentary on Copenhagen’s housing model by Greg Bamford, Queensland, who supports the Danish approach, emphasising building separation and generous provision of usable semi-private / shared outdoor space.

British density

Britain is often described as crowded. London? Well, it seems stupid even to ask the question: of course it’s crowded. But I’d like to flip the question around. How much space can a person in Britain reasonably expect? And, for comparison, how much space does he or she actually have?

Some back of the envelope arithmetic. The UK has a land area of 243,610 km2. The population is 62.5M or so. That gives 3,900 m2 per person, or 0.39 ha. A decent amount. Of course, most people live in urbanised areas; let’s concede that this is desirable for economic reasons. So, how much space can a person living in a British town or city reasonably expect?

Leeds, my home town, has an area of 562 km2 and its population is around 750,000 (source). That gives 749 m2 per person (0.075 ha). But two thirds of this area is designated as green belt (ibid.). For now, let’s accept this planning designation: it curtails the area per person to 250 m2. That’s land area. Of course, we have the technology to build multi-storey structures on the land, potentially increasing the area per person. So there’s a multiplier: the plot ratio. Let’s assume, conservatively, that Leeds can be developed to a plot ratio of 2. This ratio can be taken to allow for open space such as roads and private gardens, and hence a typical structure might be 3-4 storeys. Sounds like a reasonable development goal? OK, then. A plot ratio of 2 gives us 500 m2 per person.

Now, how much area does a person living in Leeds actually have to swing a cat? This is a hard question to answer with elegance or precision, but here goes. Around half of the dwellings in Leeds are classified as having three bedrooms; this is the most common dwelling type (source). Take this as representative. The median gross internal area, for a three bedroom house in the UK, across all tenure types, is 92 m2 (source). If you take it that a three bedroom house in Leeds is lived in by three people (this might be conservative), then around 30 m2 per person looks plausible. So what happened to the other 470 m2? Is it all given over to employment use? Railway lines? Schools? Hospitals? Parks? Is it just wasted? Reserved for grouse shooting? It’s possible I’ve gotten my sums wrong, but I have to say I find this difference – between the space people could have and the space they actually have – just flat out boggling. Call it naivety if you like.

Coincidentally, when the LSE Cities project looked in detail at the Green Street East district of Newham, London, they found 27.8 m2 of habitable space per person, comparable to my (very rough) estimate of living space in Leeds (source). In the same study, the LSE project also looked at the Town district of Hammersmith and Fulham and found 49 m2 per person. However – and this is the interesting part – when measured in terms of persons per hectare, both districts had very similar densities: 176 pers. / ha in Green Street East versus 153 pers. / ha in Town. So in Town, Hammersmith & Fulham, for a given land area, more area is available to people. It’s also the wealthier district of the two. Conceivably, the provision of this extra space in Town is explained by a higher plot ratio, although not necessarily: the only firm conclusion I can draw is that this part of Hammersmith & Fulham just does better at land utilisation. Less land is wasted: more is converted – perhaps by building higher – to habitation. Which is what we want, right?

Update: On re-reading this, it occurs to me that a problem with the topic might be equivocation over the term ‘density’. Building taller increases built form density but doesn’t have to result in higher population density (and perhaps shouldn’t). A lot of UK discussion focusses on population density while glossing over the issue of habitable space. For example, Ed Glaeser:

We maximise our damage when we insist on living surrounded by greensward. Lower densities inevitably mean more travel, and that requires energy. While larger living spaces certainly do have their advantages, large suburban homes also consume much more energy. Anyone who believes that global warming is a real danger should see dense urban living as part of the solution.

This misses something important. Energy-intensive ‘sprawl’ is bad, yes, but people like living space; we should somehow try to arrange things so that they can have more of it.



Compare and contrast. Chelsea Barracks, 5.2 ha. Sold for £959 million to a housing development consortium in 2007. Site remains empty. Woolwich Arsenal, 13 ha. Parcelled up and the best plots sold, from 2003 onwards, to housing developers such as Berkeley Homes and Barratt Homes. Large parts of the site remain undeveloped; enough for 5,000 (masterplanned) homes. Vauban, Freiburg, 38 ha. Sold, via an NGO, to a mix of private developers and baugruppen. Site is fully developed.

All of these sites were government sites (all were formerly defence sites). And while it’s arguable that the Chelsea site sale was ‘good value for the taxpayer’, there are good reasons for preferring the Vauban model over the Woolwich Arsenal model. With Vauban, the resulting development:

• Is democratic, and reflective of community needs and aspirations;
• Is socially well integrated;
• Has excellent energy performance;
• Conserves the best natural features, such as trees;
• Is interestingly diverse, being designed by or in close consultation with residents;
• Has safe, car-free residential streets (but with car ownership);
• Is popular: the entire site is now lived in.

Generally, the features of the Vauban Quarter were argued for, rather than imposed:

It was … meticulous liaison work with prospective residents that contributed to, and eventually built the necessary popular support for, some of Vauban’s most conspicuous innovations – such as the parking-free and carfree models of mobility management, the emergence of owner cooperatives (Baugruppen) as self-governed, non-profit developers and the instigation of building energy concepts far exceeding the already stringent legal requirements. Assisting people to translate their dreams and aspirations about sustainable living into feasible plans, and seeing them through a council planning department (that may be well-meaning in general terms but often sceptical in detail), became an invaluable role that Forum Vauban filled with verve, notwithstanding some inevitable conflict potential.

(Jan Scheuerer)

Of course if you look sympathetically at developments such as at Woolwich Arsenal, you can see some of the same planning ideas in play: there’s integrated public transport (the DLR extension) and developers are encouraged to create high quality public spaces, and to prioritise sustainability. But the dialogue between private for-profit developer and local authority, often antagonistic, is never going to much resemble the dialogue between future resident (and owner) and a non-profit development organisation like Forum Vauban. Developers have their own ideas about what appeals, and in Britain that often means a view of some water. In London, river front sites are strongly preferred, and are developed to very high densities. Meanwhile, other sites are neglected completely. Local authority planners struggle to give a humane shape to the outcome; often the result is very poor urban planning. Just try to take a walk along York Road, Wandsworth.

More about Vauban, Freiburg, here.