Density is just a number. What counts is quality of place

It’s increasingly clear that the GLA is pinning its hopes on higher density as the way to deliver the 65,000 homes a year the new draft London Plan shows we need. This is 50% more than the 42,000 target of 2014, and three times the 20,000-ish that has actually been delivered over recent years.

There are undoubtedly some worrying aspects to this and I read Duncan Bowie’s recent article, The new London Plan has got it wrong on density, with interest. He’s right to say that densification will put pressure on housing standards, and that family housing tends to get squeezed as density rises, but I don’t share his view that retaining the density matrix is the solution to these problems.

The matrix may have been a useful concept but has always been too blunt an instrument: the dwelling bands are too broad and it all hinges on the availability of public transport. Important though that is, it matters just as much that local schools, health centres, hospitals are not just present in the area but also have capacity to cater for additional residents. London is too “mixed up” for banding to work. Part of its unique charm is that you don’t know what to expect when you round the next street corner – and part of the designer’s role is to respond to the specific opportunities of each site. Bands of 55-225 dwellings/hectare and 200-700 habitable rooms/hectare don’t help anyone.

As Bowie himself points out, the matrix has largely been ignored in recent years anyway: around 60% of current schemes already exceed it. Any policy that is flouted to that extent must be called into question. In this case, the answer is not simply a new table with bigger numbers (they’ve already tried that), but a rethink.

The 2016 London Housing SPG quotes from a report produced by Maccreanor Lavington and others:

“Residential density policy is about everything and nothing… On the one hand it informs everything to do with housing design and management. On the other hand, the actual density calculation of an acceptable development (in terms of units or habitable rooms per hectare) is a product of all the relevant design and management factors; if they are all met, the resultant figure is what it is and is arguably irrelevant.”

They’re right; density is just a number. Yes, OK, it’s an interesting number, but with limited practical value and highly prone to miscalculation and misleading claims. A simple, contextual, massing model will tell you far more about the scale and feel of a development than a number ever could. The smaller the scheme the less useful that number becomes because so much depends on whether the development can be served by existing streets and play space, or needs to provide them. Just varying the amount of on-site parking has a huge impact on density; start factoring in schools, parks and community facilities and you find that neighbourhood density and scheme density become poles apart.

For the figures to mean anything at all, we need robust, standardised calculations. The current London Housing SPG suggests that the RICS Standard Method of Measurement should be used to calculate gross internal floor area. Devised originally for valuation purposes, it’s out of date and not the right tool; it deals with chimney breasts but doesn’t mention access decks.

A fine balance must be struck between the overwhelming demand for numbers and the need to protect quality and create a lasting legacy

The density matrix is certainly not the way to protect housing quality. This is much better tackled through other plan policies and supplementary guidance. While I welcome the fact that the strategic commitments to quality in the draft plan are stronger than ever, they mean little unless they are delivered in practice. Evidence suggests that planning officers are already finding it difficult to uphold current standards. In spite of the strong presumption in favour of dual aspect, we see large numbers of single aspect apartments, particularly for private rent. Many also lack the private open space that is currently required, and the space standard isn’t preventing micro-homes from being waived through as “sui generis”.

Before density is ratcheted up again, the GLA must reflect carefully on the “living standards” it sets. It’s certainly very difficult to achieve zero carbon at high densities; most schemes pay their way out, which isn’t really the point. Some of the basic attributes we value (daylight, sunlight and privacy are the obvious examples) come under threat as buildings get taller and the spaces between them get smaller. But we need to protect these attributes at all densities and encourage inventive design solutions rather than accept lower standards. A fine balance must be struck between the overwhelming demand for numbers and the need to protect quality and create a lasting legacy.

Bowie’s other point – the squeeze on family housing – should also be taken seriously. But that too, is better dealt with through locally set mix policies, than through the matrix. It’s over- simplistic to assume that singles and couples live in high-density flats, and families live in houses. Families can, and do, live well in flats, but there are intermediate options that could work better, even at high densities. Why not, for example, consider a “family-friendly floor” of duplexes part-way up an apartment block; setting off any extra cost against the saving on communal circulation?

My scepticism about density is mostly about the fact that the matrix has been used as an input, rather than an output. We should continue to measure and record density and in a number of different ways because different metrics tell you different things. I’d forget habitable rooms (open-plan living makes the definition of a habitable room very difficult) and go instead for dwellings per hectare (where single-person homes score highest) and bed spaces per hectare (where family dwellings do better). Some sort of aggregate of these two metrics would provide a more rounded picture and support a better mix of dwellings. I’d ask for plot ratio too.

Even so, the focus should be on how living environments work and feel in practice, not on the density they achieve on paper. Rising density will continue to affect the physical character of the city and have social implications too, but there is little evidence to suggest a direct correlation between density and quality. City Hall should also consider the very real risk that even higher densities will lead to even higher land costs and even higher prices; in theory it should bring prices down but there’s no sign of that so far. It would be tragic if higher densities resulted in higher profits and poorer housing. Success will be judged on built outcomes, not policies.