When is Demolition Justified?

Demolition has far-reaching consequences for people, nature and the climate. When is demolition and rebuilding appropriate?

Colin Rose (University College London) reflects on the recent Buildings & Cities special issue ‘Understanding Demolition’. The answer depends on better understandings of the circumstances for demolition versus refurbishment.  A more transparent, public approach is needed that involves wider environmental, social and cultural costs and benefits.

Introduction

As a major disruption to the urban fabric, it is no surprise that demolition is a divisive and emotive topic. This special issue is a timely effort to explore more reasoned approaches to the highly-charged decision-making around demolition. In a variety of contexts, the papers in this special issue aim to understand the drivers for demolition, progress towards more reliable assessment of the relative merits and impacts of demolition and its alternatives, and develop science-based tools to support practitioners. It is clear that the decision to demolish has major environmental, social and economic impacts, yet the topic remains under-explored in academia (Huuhka 2023). The research in this special issue can be built upon to improve policy and clear away some of the ambiguity that can lead to expensive and unhelpful delays in reaching planning decisions.

Understanding and influencing the decision to demolish

The special issue sets out to understand demolition, not with the a priori goal of avoiding it, but to build a picture of ‘whether and how demolition helps to build environmentally, economically and socially sustainable cities, and when it is in fact helpful toward these goals’ (Huuhka 2023, p. 928). Demolition can be part of the healthy renewal of cities. If we consider all demolition versus refurbishment¹ decisions as a cohort, then there is a spectrum ranging from typically demolished (e.g. structurally unsound, beyond economical repair) to typically saved (e.g. for heritage / cultural reasons). Policymakers can influence where the thresholds of these groups lie, for instance by widening the types of buildings that are protected by listing beyond traditional heritage categories (Huuhka 2023).

Policymakers also need to consider other factors that influence decisions about demolition that are often pivotal. The drivers for demolition include economics and profit (e.g. rising land value that makes significantly higher density on a site possible); prevailing views on the merit of certain eras of building and neighbourhood design (Jonker-Hoffrén 2023); a building’s location being incompatible with a masterplan (e.g. proposed infrastructure); and perceived risk from problems with an existing building (Baker et al. 2023).

If policymakers set more restrictive policies around demolition, owners of buildings that cannot be transformed to suit their needs would be motivated either to change their brief and expectations or to sell to someone more able to make use of existing assets. In a perfect market, this might create better allocation of end uses to buildings that can readily accommodate them. But in practice, local authorities are not motivated to set policy that drives away building owners and discourages local investment.

Assessing and comparing options

If local authorities struggle to set a blanket policy to influence all demolition versus refurbishment decisions, this could come from regional or national level. Baker et al. (2023) provide evidence to support the introduction and standardisation of embodied carbon measurement within national regulation, which would ‘seem highly likely to become a key driver towards the retention of buildings’. In London, the metropolitan authority (the Greater London Authority – GLA) has attempted, inter alia, to tip the market in favour of refurbishment through two policies introduced in the last London Plan (GLA 2021, policies SI 2(F) and SI 7) and accompanying guidance on circular economy (CE) statements (GLA 2022a) and whole life-cycle carbon (WLC) assessments (GLA 2022b). These submissions are required for the largest developments.

A recent case generated much controversy and reveals why assessment can influence outcomes. An application to demolish a 1929 art deco flagship department store in London (Marks & Spencer – M&S) and then build a new department store on the same site rested much of the argument on the carbon emissions. The WLC assessment for M&S arrives at the conclusion that the new build scheme, with its significant carbon spike (almost 40 million kgCO2e in modules A1-A5, Arup 2021b), achieves carbon payback after 16 years (Arup 2021b). The proposed scheme is compared to a ‘light touch refurbishment’ that does not upgrade the thermal performance of the existing building (effectively a ‘do nothing’ option). Clearly this is not a like-for-like comparison. The range of potential refurbishment options are represented by a single ‘straw man’ option that is bound to fail (DLUHC 2023). The approach seems biased towards justifying demolition. The applicant’s position, however, is that this is the realistic alternative to a new build scheme.

Improving the assessment process

Huuhka et al. (2023) apply the concept of ‘consequential replacement framework’ (CRF) to buildings. This provides good methodological proposals that could be adopted to improve policy:

• Include emissions from demolition in analysis and decision-making.  Often guidelines (e.g. RICS and normal LCA) for projects exclude demolition of an existing asset from WLC assessment.
• Assess a range of realistic options. The demolition versus refurbishment decision is often presented starkly in practice – black and white options – whereas a sensitive and thoughtful approach to all elements of an existing building, carbon implications, aesthetic opportunities etc., might suggest a range of adaptation options – some more radical and interventionist, some more preservative.
• Compare fairly and allow findings to influence decision-making.
• Provide clarity over functional unit. There is no point in claiming refurbishment would be cheaper if the practical economic comparison is with a new build scheme that is more profitable because planning permits it to be much taller. Cost and carbon assessments should be conveyed in absolute real numbers for a project as well as per m² rates.

The CRF approach seems to provide a reliable and valid comparison of options. The same method can also be used for life cycle costing. However, the results of single assessments do not determine whether or not permission is granted in the UK and many other countries: planning permission for complex schemes is not a checkbox exercise. Each factor in the decision-making process is qualitatively weighted in the project’s specific context to determine the overall balance in favour of or against consent. Credible and robust assessment of the impacts of demolition versus refurbishment would allow more weight to be placed on this factor.

Expanding system boundaries versus simplifying assessments

Where path dependency leads developers to keep choosing the less favourable option, understanding the reasons for demolition can be the first step in setting appropriate policies to support and encourage desired shifts. It can also lead to development of tools and strategies that help practitioners to switch to retention, when that is favourable. 

To be robust and meaningful, LCA tends towards increasing complexity of assessment (categories, timeframes, scales), and becomes more onerous rather than more simple to use in practice. Lundgren (2024) assesses social impact in adaptive reuse project and notes the increasing number of impact categories under consideration. For example, one important social factor that is relevant to many demolition and densification cases is access to affordable housing.

Several papers in this special issue grapple with the complexity of measuring all the implications of demolition (Huuhka et al. 2023; Lundgren 2024; Zimmerman et al. 2023). Further development of LCA is needed to strike a balance between thoroughness and more nimble tools that allow developers and design teams to easily compare different demolition and refurbishment scenarios at strategic stages.

Deconstruction and reuse

Another area of focus for the special issue is the use of materials when buildings are demolished or deconstructed (van den Berg et al. 2023; Zhang & Lee 2023). A future expectation is the large-scale reclamation and trade of used building components emerging from buildings that were designed for disassembly and reuse. Information will be retained on digital platforms that gather material passports. While this is harder to achieve for older materials emerging from the existing building stock, the scale of these flows demands action to improve upon current waste management.

Van den Berg et al. (2023) collaborated with a demolition contractor to develop a decision-support tool for selecting material end-of-life strategies. The tool helps demolition contractors decide whether materials in existing buildings should be sent for reuse, recycling or recovery, by evaluating technical feasibility (e.g. of effective reclamation), costs and environmental and social gains. This is a valuable contribution that tests assumptions in favour of waste management (recycling/recovery), and could instead enable ‘component management’ (Rose & Stegemann 2018). The tool identifies what cost of deconstruction would be justified by the revenue from selling reclaimed materials, or by other benefits of reuse.

Sufficiency and demolition

Policy can influence the factors at play in demolition decisions, e.g. by setting expectations of site density or building height. Given rising urban populations, this densification may be an example of demolition’s function as a route towards environmental, economic and social sustainability. Many parts of Europe have a scarcity of affordable housing.

However, this deserves to be challenged. For example, floor area per capita, a measure of lifestyle, is high and still rising in Europe (Müller 2006; Ness 2020; Vásquez et al. 2016). If we take the view that in most of Europe the per capita rate is sufficient, then the problem becomes (a perhaps even more intractable) one of equitable sharing of existing assets, rather than how to sustainably increase the stock.

Extending the time horizon beyond the next generation’s access to housing may also cast doubt on the wisdom of building more homes in Europe. Global population is expected to peak in the 2080s (United Nations 2022); some nations’ populations are already falling. European total fertility rate has dropped below 2.1 and by 2100, Europe’s population is predicted to drop by 20% compared to today (Statista 2024). Is it better for a couple of generations of Europeans to live with unenhanced floor area per capita, rather than building vast numbers of new homes in a critical period for the global CO₂ budget, and creating a possible surplus in the future? Which parts of the world will be inhabitable by 2100 and what will be the patterns of climate migration? These questions are outside the scope of this special issue, and point to the need for collaboration across disciplines – demography, political science, climate justice, economics, urban planning – to inform policy. Whilst the papers in this special issue address demolition at building, masterplan or city level, the topic is part of the grain of these wider challenges.

Note

1. For brevity, ‘demolition versus refurbishment’ is used as shorthand for ‘demolition and new build versus the alternatives to demolition’, which in practice are multiple and varied – this is rarely a binary decision.

References

Arup. (2021a). 458 Oxford Street: Whole life carbon assessment (part 1). https://idoxpa.westminster.gov.uk/online-applications/files/DFCD081BC0E184426C3444D523E4EBC4/pdf/21_04502_FULL-WHOLE_LIFE_CARBON_ASSESSMENT_PART_1_OF_2-6921336.pdf

Arup. (2021b). 458 Oxford Street: Whole life carbon assessment (part 2). https://idoxpa.westminster.gov.uk/online-applications/files/40A3F7A3C334CD7FCE36E4D39705A915/pdf/21_04502_FULL-WHOLE_LIFE_CARBON_ASSESSMENT_PART_2_OF_2-6921343.pdf

Baker, H., Moncaster, A., Wilkinson, S. & Remøy, H. (2023). Demolition or retention of buildings: drivers at the masterplan scale. Buildings and Cities, 4(1), 488–506. https://doi.org/10.5334/bc.308

DLUHC. (2023). Application made by Marks and Spencer PLC 456-472 Oxford Street, London W1. https://assets.publishing.service.gov.uk/media/64b90f082059dc00125d265b/23-07-20_DL_+_IR_456-472_OXFORD_STREET_LONDON_W1_-_3301508.pdf

GLA. (2021). The London Plan: The spatial development strategy for Greater London. https://www.london.gov.uk/sites/default/files/the_london_plan_2021.pdf

GLA. (2022a). London Plan Guidance: Circular Economy Statements. https://www.london.gov.uk/sites/default/files/circular_economy_statements_lpg_0.pdf

GLA. (2022b). London Plan Guidance: Whole Life-Cycle Carbon Assessments. https://www.london.gov.uk/sites/default/files/lpg_-_wlca_guidance.pdf

Huuhka, S. (2023). Understanding demolition. Buildings and Cities, 4(1), 927–937). https://doi.org/10.5334/bc.398

Jonker-Hoffrén, P. (2023). Policy tensions in demolition: Dutch social housing and circularity. Buildings and Cities, 4(1), 405–421. https://doi.org/10.5334/bc.305

Müller, D.B. (2006). Stock dynamics for forecasting material flows: Case study for housing in The Netherlands. Ecological Economics, 59(1), 142–156. https://doi.org/10.1016/j.eco lecon.2005.09.025

Ness, D. (2020). Growth in floor area: the blind spot in cutting carbon. Emerald Open Research, 2, 2. https://doi.org/10.35241/emeraldopenres.13420.1

Rose, C.M. & Stegemann, J.A. (2018). From waste management to component management in the construction industry. Sustainability, 10(1), 229. https://doi.org/10.3390/su10010229

Statista. (2024). Forecast of the world population in 2022 and 2100, by continent. https://www.statista.com/statistics/272789/world-population-by-continent/

United Nations. (2022) Population. https://www.un.org/en/global-issues/population

Van den Berg, M., Hulsbeek, L. & Voordijk, H. (2023). Decision-support for selecting demolition waste management strategies. Buildings and Cities, 4(1), 883–901. https://doi.org/10.5334/bc.318

Vásquez, F., Løvik, A.N., Sandberg, N.H. & Müller, D.B. (2016). Dynamic type-cohort-time approach for the analysis of energy reductions strategies in the building stock. Energy and Buildings, 111, 37–55. https://doi.org/10.1016/j.enbuild.2015.11.018

Zhang, Z., & Lee, J.D. (2023). Decision-making analysis for Pittsburgh’s deconstruction pilot using AHP and GIS. Buildings and Cities, 4(1), 292–314. https://doi.org/10.5334/bc.306

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