MESH Construction Consultancy’s Zoe Curnow and frequent collaborator Richard Woods, of Urban Fabric Architects, discuss alternative approaches to business as usual

The climate emergency is indifferent to postcode. With the fate of the Marks and Spencer’s Building on Oxford Street hanging in the balance, it continues to generate huge media interest. Relatively recent buildings are routinely demolished, and the majority of the time no serious examination is given to retrofit opportunities. These may be in places where land value has less market interest, nor significant architectural merit. But on one crucial level this is immaterial: the squandering of their embodied carbon will have precisely the same deleterious impact on the climate emergency as the demolition of more prestigious buildings in more prominent locations.

The UN’s Emission Gap Report 2022 makes for stark reading. Their environmental agency sees “no credible pathway to 1.5C in place”, while “the failure to reduce carbon emissions means the only way to limit the worst impacts of the climate crisis is a rapid transformation of societies”. We simply cannot assume we can continue to demolish old buildings and build new replacements without consequence.


Herefordshire School

Through working on Design Review Panels in various parts of the UK, Woods has witnessed numerous design presentations where the proposed removal of an existing building (sometimes with architectural merit) passes without mention, or examination of whether the building could be re-purposed. What might incentivise a different approach which takes seriously the heft of embodied carbon of any existing building, together with the embodied carbon of its replacement?

In London, we are seeing the beginnings of a response to this challenge with the publication of the latest edition of the London Plan, where Whole-life carbon assessments (WLCAs) are required for any schemes taller than 30m or providing more than 150 homes. Whilst this is welcome, WLCA is an assessment method in its infancy. It calculates the impact of whole life operational carbon against embodied carbon, based off important but speculative assessments of future scenarios. Due to the difficulty WLCAs are to undertake without substantial financial backing, there are some concerns that they are unlikely to be independent assessments.

Meanwhile, Architects Declare are calling for more comprehensive and country-wide initiatives to address the current propensity towards demolition. Amongst proposals being brought forward is a suggestion for the government to lead by example by setting a programme to retrofit all public buildings to comply with sustainability standards. Another is to “leverage planning permission to facilitate built environment interventions that address the climate and biodiversity emergencies. For example, to offer faster planning periods for retrofit schemes and to put checks in place to disincentivise interventions that exacerbate the climate and biodiversity emergencies, including requiring permission to demolish a building”.

It possibly isn’t too pessimistic to believe that the government is unlikely to implement these proposals any time soon. The latest cabinet reshuffle has demoted the environmentally committed Amok Sharma, and has brought in David TC Davies as Welsh Secretary, who has written that spending money fighting climate change is irresponsible, stating that “I am concerned that we are spending a vast amount of money on tackling man-made global warming when the problem may not even exist.”

Therefore, positive change must come from the construction industry itself. Over the last 18 months Urban Fabric Architects and MESH Construction Consultancy have undertaken an extensive series of cost designs for local authorities, to support with the increase of pupil numbers. These include feasibility studies for Milton Keynes Council and Herefordshire Council, where we provided three developed design options for 21 separate school sites.

With very close collaboration between the client team, cost consultant and architect, we have brought detailed scrutiny to assessing new-build options against “deep energy retrofit” alterations, which would also address accessibility deficits. The studies required both new-build and retrofit options to achieve operational carbon zero. Though retrofit proposals inevitably require more complex phasing considerations, and sometimes the requirement for temporary accommodation, consistently they were shown to provide substantially more economic solutions.

Retaining existing buildings can bring more nuanced benefits too. Several years ago, during the Wolverhampton Building Schools for the Future programme at King’s School, Woods encouraged the retaining and enhancing of an existing 1950s school block over re-provision with new-build accommodation, which was the client’s original presumption. The only credible place to locate the new build would have been through the removal of a group of deciduous trees in the school’s courtyard. The option for a “shiny new building” was revoked, and Woods was able to implement the retrofit option, which benefited from both a substantial save in costs for the renewal of an existing building and the retention of the courtyard.

This does not just apply to educational buildings. At MESH we have recently started working with a London landlord to develop a “waste less” concept of refurbishing office space using as little new materials as possible. Collaboration is at the heart of success for this approach, requiring not only design team coordination, but engagement from the outset with a main contractor and their supply chain to source re-used and re-cycled materials. It can often be more expensive to procure bespoke upcycled materials and products than to buy new, so the level of specification will need to be carefully balanced with the client’s affordability limits to ensure lettable but also profitable space is created.

Curnow reflects on the challenges this presents financially. It is difficult to obtain early cost certainty given materials are selected as and when they may (or may not) become available; and given the bespoke nature of the fit-out it is equally difficult to accurately benchmark costs of future “waste less” projects for landlords, developers, and tenants alike. This project highlights the complexity of sustainable development; in this instance M&E plant being re-used to avoid buying new and reducing embodied carbon, but some could see this as a lost opportunity to install new better performing plant. We acknowledge there is no one size fits all solution to retrofitting existing buildings.

Existing buildings hold cultural value too. Laura Baron of Purcell has recently set out ways to address improved environmental performance in prestigious historic buildings through Constructive Conservation. This is self-evident for more prestigious heritage assets. However, buildings of more minor significance can also hold an important place in a community’s collective memory. In Scarborough, Urban Fabric recently retrofitted the Victorian beachfront public toilets after decades of decline. We were able to rescue and repair four historic tiled panels which were intended to be disposed of and integrated them into the new fully accessible layout. The public popularity of the retrofitted facilities is testament to the importance that any building can have in a community’s collective memory.

We have discussed, retrofitting schools as schools, and offices as offices, but we challenge the industry to go one step further: to be creative in how they re-use buildings, and what for. In the last couple of years, we have seen an increase in commercial buildings being repurposed for healthcare and life sciences. This presents obvious challenges (some of which Tim Molden of MESH explored in the article ‘Why other sectors should follow healthcare in embracing modular’, which you can read here. However, we should not simply opt for the simple solution without exploring alternatives. In the past we have successful repurposed a banking hall as an office, and a retail unit as a health centre, demonstrating this can be done sustainably.

The UN’s Emission Gap Report 2022 conceives of a closing window of opportunity to prevent climate disaster. We urge creative and credible collaboration across disciplines, to help clients recognise the clear benefits of retrofit. Not every existing building should be retained, and not every new building is a misstep. However, we need to grow a construction culture where new build increasingly becomes the exception and retrofit the rule.