Affordable housing, viability and the limits of sustainable development in London

The Michael Welbank Bursary is awarded by the RTPI Trust and provides one-off financial bursaries for students taking RTPI accredited planning courses at universities in London.

The bursaries are targeted at disabled students, students from groups and backgrounds under-represented in the planning profession, in particular, those of Asian, African or Caribbean heritage, and students with personal or domestic situations e.g. caring responsibilities, which impact their ability to meet the financial commitments of studying.

The 2026 bursaries were awarded to applicants Oge Anyokwu and Anna Redmond, who were asked to write blogs giving their perspective on planning in London communities.

Anna’s blog explores viability assessments and the tension between the current housing supply ambitions and the delivery of affordable housing for Londoners, in what she refers to as the 'field of compromise'.

Anna is studying the Town and Country Planning PgDip at London South Bank University.

Online applications for the 2027 Welbank bursaries will open in March 2027.

By Anna Redmond

London’s housing crisis is often presented as a problem of insufficiency: not enough homes, not enough supply, and not enough delivery speed. National and regional planning policy therefore places significant emphasis on increasing housing provision, with ambitious targets intended to respond to persistent demand.

Yet throughout my planning studies, I have become increasingly drawn to a more difficult question: if the homes being delivered are not affordable to those who live and work in the city, to what extent can this be understood as sustainable development?

Planning is founded on the principle of balancing environmental, economic, and social objectives. Within this framework, affordable housing sits within the social dimension of sustainable development, representing a key component of inclusive urban growth. Access to secure and affordable housing is widely recognised as fundamental to enabling participation in the economic and social life of the city.

Within the London planning context, however, this objective is continually negotiated through the language of viability. The planning system seeks to secure social value through affordable housing provision, yet it is also dependent on private sector delivery to meet overall housing need. As a result, affordable housing is often balanced against the financial feasibility of individual schemes, embedding negotiation at the heart of planning decision-making.

Viability assessments sit at the centre of this tension. Intended to ensure that development is deliverable, they test policy requirements against market conditions such as land values, construction costs and expected developer return. While this mechanism can support development coming forward, it may also result in reduced affordable housing contributions in certain circumstances, highlighting the balance between policy ambition and delivery outcomes.

This dynamic can be understood as a policy–profit tension. Planning seeks to secure social outcomes through development, while also operating within a market system driven by investment, risk and financial return. The outcome is a system in which affordable housing provision is not fixed, but subject to ongoing negotiation and local context.

The implications for London’s housing market are significant and spatially uneven. As affordability pressures increase, access to the city becomes more stratified. Key workers, younger households and lower-income groups may be pushed towards outer London or surrounding regions, contributing to longer commuting patterns and reinforcing spatial inequality. Housing therefore functions not only as a market commodity, but also as a gateway to urban opportunity, shaping patterns of inclusion and exclusion.

This raises broader questions about London’s growth model. A system that continues to produce housing that is unaffordable to significant parts of the population risks reinforcing inequality within a context of continued expansion. While housing delivery may increase overall, the distribution of benefits may be uneven, which challenges how far the current model can be considered sustainable in social terms.

Of course, the alternative is not straightforward. More rigid affordable housing requirements could constrain viability and reduce overall delivery, with implications for housing supply. Planning therefore operates within a constrained field of compromise, where policy ambition and market realities must be carefully balanced.

Ultimately, the challenge for planning practice across London’s development landscape is not only to deliver more homes, but to ensure that growth is inclusive in its outcomes as well as ambitious in its scale. Until the tension between viability and affordability is more effectively addressed, London risks a development model that is economically productive but delivers uneven social outcomes. This raises an important question for planning practice: not only how many homes are delivered, but for whom the city is ultimately shaped.