Day 9: Housing supply (SHLAA) and targets [M19], part 1

Photo: Dave Pearce (CC BY-NC-ND 2.0)

Housing and Urban Form: Tensions in the London Plan Examination in Public
Prof Christine Whitehead | LSE London
LSE, Knowledge Exchange and Impact fund

M19: Housing supply and targets

In many ways this topic – about whether the 10-year housing targets for London and the individual boroughs are justified and deliverable – lies at the heart of the draft London Plan with respect to housing. One would have expected this to have generated two of the most exciting and instructive days in the whole of the Examination in Public (EiP). In practice it seemed to be rather mechanistic – more focused on whether the SHLAA and the SHMA had followed the ‘rules’ for matching land supply and housing needs than on whether the figures are unrealistic in terms of the likely delivery of additional dwellings.

The scene was set by an agenda requiring a dozen sub-questions to be addressed one by one, rather than directly tackling the over-arching ‘matter’ in question (as had been the case in earlier sessions). The specified sub-questions were a very mixed bag, with no obvious logic to their ordering, or reason to believe that answering them all would provide an answer to the general question. Notably, an initial sub-question covering the ‘capacity’ of large sites was not matched by one about delivery of this capacity, nor was there anything about small sites (the subject of a later ‘Matter’). Some synthesis only came at the start of day two when sub-question (g) asked what was going to bring about the (very large) overall step-change in delivery implied by the Plan.

The starting point of the discussion was around the contribution to capacity coming from large sites – where the methodology was very similar to earlier Plans (except for a new, more realistic basis for estimating likely densities of development) and the measured capacity was also quite similar once allowance was made for the change in densities. As such there was little to criticise and local authorities seemed happy to accept this element of the SHLAA.

Even so, capacity of itself is not the point – a significant issue remains about when, and if, sites that are potentially available will actually come forward and get developed, since actual speeds of development in previous periods had fallen well short of planners’ expectations. There are undoubtedly a variety of reasons for sites not coming forward. But in the absence of clear remedial action, or evidence that exogenous factors are reducing this development gap, our view is that it has to be assumed to continue through the period of the NLP. The baseline expectation would then be of only a very modest increase in the scale of delivery from this source, maybe proportionate to that in large site areas between the 2013 and 2017 SHLAAs. That would leave an enormous gap between the Plan’s large site capacity estimates and the likely scale of delivery.

Logically, this gap might have been closed by increased building on smaller sites, where the same delivery constraints might not apply – especially as the Plan embodies a significant new GLA small sites initiative that could be delivered within the GLA’s current legal and financial resources. In fact, the scale of output growth from such sites (which is directly included in the capacity estimates, though using a different logic) is clearly much smaller than the delivery gap on large sites. If expectations were fulfilled, overall housing output might be expected to increase quite substantially (by perhaps 18K dwellings p.a.) but that would still not get half way to the growth target set in the Plan. And, in any case, there are very real questions about whether the small site sub-target could (or should) be met, many of which (naturally) came up in discussion on this Matter – even though direct consideration was scheduled for a separate session in the following week.

The core problem is that the specific kinds of (very small) sites from which the GLA expects to stimulate/enable a much greater level of intensification and infill currently represent only a small fraction of housing output (perhaps 15% of the trend level), making this unlikely as the main engine of increased London housing delivery in the next decade or so. For this category of sites, the SHLAA envisages a totally incredible quintupling of output in the next decade, as compared with the last 8 years – up from 3.6K p.a, to 18.7K. There seems scarcely any evidence – and effectively none actually deployed – as to what might be achievable through the application of the set of small site policy changes set out in the Plan. But banking on a transformation on this scale needs very solid evidence to back it up, rather than the simple conjectures that underpin the SHLAA’s ‘modelling’.

Another issue, of a more political kind, is that the potential capacity of small sites is very differently distributed, between individual boroughs, but also between the broad groups of inner versus outer boroughs. Notably, as representatives of outer areas have highlighted (usually negatively, in varying degrees) the latter are being expected to enable and accommodate a substantially larger proportion of the planned net housing growth than has traditionally been the case, when reliance were placed much more heavily on the development of large sites. As the GLA point out, relative to size of the existing stock, overall planned growth is still a bit lower than for inner London across the outer boroughs as a group. But this still means that some 80% of the planned intensification is expected to be in outer boroughs.

Discussion about the realism of the small site capacity and delivery assumptions, their impact on area character, and the reasonableness of transport accessibility assumptions embodied in the estimation of small site development potential in outer boroughs were to come to the fore in the next scheduled ‘Matter’. So, all we could really do at this stage was to express our disbelief both in whether the capacity could be effectively identified and in whether there was any chance of such numbers being produced within the next decade (let alone its potential impact on the proportion of affordable homes that could be achieved).

To be honest much of the rest of the discussion was desultory. The day’s sub-questions had either already implicitly been answered in the negative or were not really answerable at this stage – e.g. how can one assess whether environmental and social implications of the proposed increase in housing targets have been fully and properly assessed when the fundamental story does not make sense. In particular, how can one assess the impact on outer boroughs when in some boroughs the small sites target would imply modifying one in five dwellings in the borough!

So, at the end of the first day, our understanding of the situation was that with respect to capacity the large sites estimates differed little from those in the last Plan – which have clearly not been realised; while the capacity of small sites was based on statistical modelling which in principle identified capacity but with no reality check in terms of whether these sites would come forward. Actual delivery is another matter – to which we turned in the next session.

All of our blog entries for this project can be found here. An introduction to this project can be found here.

This document can be downloaded in PDF form here

Follow us:


Leave a Reply

Your email address will not be published. Required fields are marked *