Density and Amenity

A sustainable solution to London's house building crisis

London is in the middle of a housing crisis.  The growing demand for homes in the UK capital far outstrips supply, and means that the city is facing its most serious housing shortage since the 1950s.  In 2013, only 16,800 new homes were built in London, when the number needed (42,000) was more than double that figure.  This crisis is nothing new; we have been building less than half the number of new houses needed for a decade. During the next ten years it is anticipated that the number of people living in London will increase by the equivalent of the population of a city the size of Birmingham.  At this rate, the housing crisis will become even more severe.

Inevitably, this under-supply of new homes has economic consequences.  Recent data from the ONS shows that the average cost of a house in London has edged above £500,000 for the first time.  The cost of a house in relation to the amount a person earns is a well-established measure.  In England, and particularly in London, this ratio has soared to over 8 times earnings and is now touching 9 (see graph).  Rising ratios such as this have resulted in new MMR regulations which are intended to restrict lending if the differential between house prices and earnings becomes too great.

All the main political parties seem to agree that the need to build more homes is paramount.  The government has relaxed planning rules and introduced new incentives in a bid to facilitate this.  The Labour Party has announced plans for a National Infrastructure Commission to ensure the supply of 200,000 new UK homes by 2020.  The London mayor, Boris Johnson, is reportedly working on ‘Further Alterations to the London Plan’, which propose a housing target of 49,000 new homes each year. 

 However, despite the economic incentive of rising prices, the number of new homes being built remains stubbornly low.  The London mayor’s plan to increase threefold the number of homes being built will do little to improve matters, unless all local authorities accept the need for greater density within their boroughs. Planning rules need to reflect greater density as well, or there is a danger that ‘nimbyism’ will prevail and hamper plans for increasing the number of new-build properties.

 The details concerning the number of completions in 2013 illustrate the problem.  According to ONS data, only 20 new homes were built in Kensington & Chelsea in 2013.  Other boroughs also fared poorly, with 80 new homes built in Harrow, 110 in Kingston, 170 in Hammersmith & Fulham and 220 in Richmond.

 In an article in the Evening Standard reporting on these statistics, Richard Tamayo, commercial director of the National Home Building Council, is quoted as saying that too many London town halls are still dominated by ‘nimby’ self-interest, which makes it difficult to secure planning permission.  He says: ‘Let’s get the planning permissions through or we are going to disenfranchise a generation.’

 In order to reverse the decade-long failure to deliver sufficient homes for Londoners, developers need to be encouraged to increase the density of planned developments. Some local authorities have already recognised this, but are struggling to reconcile it with the guidelines they see as necessary for ensuring reasonable standards of living accommodation.  This is because our current need for greater housing density is being considered in the light of historic and inappropriate standards. And while these standards are not wrong, they are simply outdated for the current schemes and locations.

As our cities become more densely populated, one standard that requires greater understanding is the availability of daylight and sunlight to new developments and their neighbours.  In London, most local authorities refer within their UDPs to the Building Research Establishment (BRE) guidelines to determine whether there will be an impact upon neighbouring properties and whether the quality of light within a development is acceptable. In addition, the guidelines consider the effects of overshadowing.

The BRE suggests using a few key tests to determine whether a new development is acceptable for daylight and sunlight.  The summary guidelines suggest that a Virtual Sky Component (VSC) of 27%, or a reduction in VSC of less than 20% should apply to existing buildings. They state that this recommendation should be interpreted flexibly, and that in city centres different target criteria should apply. In practice, consideration is given only to the headline criteria.

But planning officers frequently interpret these ‘guidelines’ rigidly and simplistically, often treating the assessment of a proposed scheme as a tick-box exercise and without giving consideration as to whether the levels of daylight and sunlight are acceptable. This is perhaps unsurprising, as detailed understanding is necessary to appreciate what these criteria mean in a practical sense, particularly in city centres.

For example, while more than 20 per cent loss of sky visibility is deemed material, the guidelines do not differentiate between a postage-stamp-sized window and an entire glazed wall.  If the householder can only see 5 per cent of the sky from his or her window, will the loss of 1 per cent visibility (i.e. a 20 per cent reduction) be material?  The problem does not lie with the BRE guidelines specifically, as they allow flexibility; instead it stems from the fact that the people who need to make decisions in this area are unlikely to be informed as to what may or may not be appropriate.



Minimum acceptable daylight and sunlight levels need to be reconsidered against the need for increased housing densities. It is not enough to consider it in isolation; it should be taken in context with the overall level of amenity.  The Oxford English Dictionary definition of amenity is 'the pleasantness or attractiveness of a place’. Daylight/sunlight is only one aspect of this pleasantness.  In residential schemes, the following factors can also contribute to amenity:

1.    Orientation
2.    Room Volume and Layouts
3.    Outlook
4.    Window Size
5.    Internal Finishes
6.    External Finishes
7.    Balconies
8.    Access to Open Space
9.    Privacy
10.   Sense of Enclosure 


Thoughtfully designed developments that take into account all these aspects should be encouraged and not adversely affected by strict adherence to rigid daylight and sunlight criteria.

Central and local governments need to recognise that greater flexibility is required to promote this approach. The BRE guidelines were originally published in 1991 and last revised in 2011; in the interim, there have been significant advances in the technical analysis and simulation of daylight.  Software such as Radiance, developed by Lawrence Berkeley Laboratories, is widely regarded as the most accurate tool available for daylighting and artificial lighting analysis and simulation.  But while tools such as this produce accurate simulations of proposed developments, we still rely on rigid and simplistic guidelines such as the VSC criteria.

Either a supplementary BRE guide needs to be written specifically for city centres or the evolving London Plan needs to incorporate this approach, to support the advanced technical analysis now available and to demonstrate to local authorities the many ways in which amenity can be improved. While this would invite developers to undertake more detailed studies to show a commitment to creating better environments, it will also permit denser building schemes that have been rigorously tested to optimise or ameliorate amenity. This will then lead to more intelligent designs and better environments.

The clear message to developers is that in order to increase residential development beyond current guidelines, proposals which demonstrate good design and ameliorate amenity are most likely to be successful.