What lessons does Cambridge green belt project offer?

Nearly 100 years after the introduction of the green belt – one of Britain's most popular planning measures – is its original aim still valid? If so, is the green belt itself the best way to achieve this objective while fulfilling other equally important obligations to create sustainable communities?

The concept emerged as a way of providing a boundary for new garden cities in the late 19th century, and by the 1930s had become a broader response to sprawling development. Formally proposed in the London Plan in 1935, it was then incorporated into the Town and Country Planning Act 1947.

The policy encouraged local authorities to curtail urban sprawl by creating a ring of open, undeveloped land around their towns and cities, protecting this area from development and restricting the outward expansion of settlements on valuable agricultural land.

However, the context for urban development in the 21st century differs significantly. Affordable housing for a growing population that is close to employment has become a critical objective of the plan-led system, and people's expectations of their cities have changed. But is this sufficient justification for a comprehensive review of such a popular strategic planning measure?

To answer this question, RICS is looking at how more housing could be provided, and reviewing its own position on the way green belt policy should evolve to inform public debate.

The focus of the round-table was whether the successful development of Eddington, which has taken several decades to realise, could serve as an exemplar in the redesignation of green belt land for sustainable development elsewhere, or whether the circumstances were unique to Cambridge with its patient funding sources and could not be replicated.

In contrast, Oxford for instance has resisted changes to its green belt, and some have attributed its extreme housing shortage to the rigid pursuit of this policy; though flood-plains and transport may also be factors.

Nevertheless, the broader question is whether green belts can be partially developed to service their expanding communities while at the same time providing beneficial access to open areas.

Participants at the RICS round-table, which was hosted by the University of Cambridge, included its development director and masterplanner for development, as well as its former estates director and Cambridge City Council's former city planner. Both of the latter had been instrumental in the redesignation of the land in the 1990s.

Also participating were a number of practitioners, including RICS members, representatives of Homes England, the British Property Federation, the Home Builders Federation, the Country Land and Business Association and the Royal Town Planning Institute, and academics from the London School of Economics, University College London and the University of Cambridge itself.

Although the regional level of the UK planning system is now defunct, regional planning guidance published in 2000 went on to advocate the city's expansion to the north west, and critically informed development policies during the early planning stages.

North-west Cambridge was again identified in the Cambridgeshire and Peterborough structure plan 2003 as the site for major change, anticipating the release of green belt land for development following a boundary review.

Once released, that land was only to be brought forward for development as and when the university could show a clear need to do so. The university duly identified a need for affordable housing for its key workers, and was active in advocating reclassification of this green belt land through various consultations from regional to area action plans (AAPs).

In 2008, the draft development plan's examination in public focused on the needs of the university, the mix and viability of development, and matters relating to the green belt, environmental footprint and open space. This draft plan was approved the following year, and the north-west Cambridge AAP was adopted, reflecting best practice in environmental sustainability.

While the plan would entail revision of the green belt and the creation of a new landscaped urban edge, these would preserve the unique character of Cambridge, enhance its setting and maintain the separate identity of the nearby village of Girton.

After consultation, a more detailed masterplan formed the basis of the university's outline planning application. This was granted permission in January 2013, and the scheme is still under construction.

Overall, along with 1,500 homes for its key workers, it is providing accommodation for 2,000 postgraduates as well as 1,500 homes for sale and 100,000m2 of research facilities. Plans also include a local centre as well as parklands, playing fields, sustainable transportation and an extensive cycle network. As the scheme has evolved, open space increased to 50% of the site area.

Phase one of construction in 2013 provided more than 1,300 homes. There were also central amenities including a school, community hall, shops and a health centre, as well as a hotel and key primary infrastructure. Many of these necessitated capital expenditure to ensure that early residents were fully supported.

Most cities with green belts are now experiencing housing shortages, and redesignation may be one option to remedy this; but they would have to bear this potential time frame for expansion in mind if operating through the current planning system. Nevertheless, although public policy implies that green belt development is only permissible in exceptional circumstances, such reallocations in fact take place all the time.

What justifications or incentives might enable redesignation from green belt to development land? The fact that more than 50% of land reallocated is becoming recreational open space was a significant incentive for the local community in north-west Cambridge.

In this case, the university's unique requirements, its ownership of land immediately adjoining it in the green belt, the quality of development proposed and the proximity of students and employees – including key workers – to their place of study, research or work provided a compelling argument for reallocation. But even then it took a long time to process through the existing planning system.

One academic who had researched the London green belt questioned whether there should be a super levy on developers benefitting from such reallocations, given the historically ascribed permanence of the designation and the fact that windfall gains are similarly obtained by local authorities when reallocating agricultural to development land.

Once the regional planning guidance had identified north-west Cambridge for development, the AAP and detailed masterplan fleshed out that guidance. The decision-makers reported a generally positive response from the city council and the community, although the risk of congestion around Girton village drew objections from its parish council.

The proposal was subject to extensive consultation at various stages. The university also proactively engaged with local and national stakeholder groups, encouraging the establishment of a residents' association to develop a consolidated view with input from Cambridge Past, Present & Future and the Campaign to Protect Rural England, now simply CPRE the countryside charity, among its stakeholders.

As part of the open debate to inform RICS' position, the round-table discussed whether green belt redesignations can be more constructively dealt with through a regional scale of planning in a designated hierarchy, rather than working through a patchwork of individual plans at local authority or district council scale without any binding obligations to cooperate.

The international status of the University of Cambridge provided a compelling case for its expansion, particularly at this location. There were a few objections to the plan, mainly because of its proximity to Girton, as the project focused on the university rather than the city community. However, the university's record of stewardship of its estate over centuries makes it a credible master developer and custodian of a multi-phased complex development on green belt land, once considered sacrosanct by residents.

Recently, there has also been greater willingness to discuss the role of green belts around towns and cities more generally. Research from 2016 carried out by the London School of Economics and the London Society, for instance, is being re-examined by academics and others in the sector, while incremental adjustments have been made to green belts by offsetting development with the provision of land elsewhere.

Eddington is probably the most comprehensive proposal of this type being implemented, and will be completed either to level 5 of the former Code for Sustainable Homes or, for non-residential property, to a BREEAM rating of excellent.

Yet despite the rhetoric of previous governments, reform in the planning system has historically been glacially slow. The Cambridge development was achieved through the existing planning system and advanced through regional planning guidance and the local plan-making process, and even then it took a long time.

To recreate the Cambridge case study elsewhere would require a long lead time to prepare, control of the land during that period, significant upfront investment and would be dependent on a long pay-back period. Clearly the long wait for a return on investment requires a different business model for development. Capital expenditure on infrastructure that contributes to significant capital appreciation in the long run, will require a patient funding partner.

This strategy should also have regard to the diversity of demands being placed on land, from food production and natural habitat to urban development and renewable energy. Such a strategy would provide the context in which an objective review of green belt policy could take place, alongside other options.

North-west Cambridge shows what one version of development on former green belt land looks like: the space being developed; the open space accessible to all; the density and mix of uses; and the quality of the built and natural environments.

As a spatial concept, this approach could result in the green belt ceasing to be a ring of private land around a settlement and instead becoming a series of wedges around the perimeter that alternate between development and publicly accessible open space.

Such wedges could be bounded by rail lines and roads radiating from the town centre. Could this arrangement fulfil the desire for openness advocated by the existing green belt policy, albeit in a different shape?

There is international precedent for such a concept in the form of Copenhagen. Although circumstances in one country are not always transferrable to another in their entirety, the Danish experience may help to understand how such an approach evolved.

There is an additional rationale for seeking to expand existing settlements: many declining town centres need to have their population catchments reinforced, and expansion could boost local consumption and give an incentive for modernising infrastructure.

There are of course considerable challenges to be overcome in reconfiguring former green belt land to maintain openness while developing sustainable, housing-led settlements. The first thing to do is understand what could be achieved in an appropriate framework. The second is to understand the consequences of not reviewing the green belt as a legitimate response to the UK's pressing need for housing.