SPR Seminar: Making residential property more sustainable
Monday 10 October 2022
If there’s a will there’s a way
In this seminar hosted by Savills, two architects set out detailed roadmaps for reducing the carbon emissions from residential property. Marion Baeli of PDP explained how it is now possible to retrofit older stock to retain heat much more efficiently, while Sunita van Heers of SuReal explored some of the materials and technologies that could revolutionise the sustainability of newbuilds – both in terms of the embedded and operational carbon emissions.
Before the meeting moved on to the potential solutions, Millie Todd of Cushman & Wakefield summarised the scaIe of the challenge in the UK, where homes account for 13% of greenhouse gas emissions, based on 2019 data. Although there has been a gradual improvement in energy performance this millennium, 54% of homes are still rated D or below on the EPC scale, and while rented accommodation looks set to be mandated C or better in 2025, owner occupied assets are a far bigger issue. There are some promising trends, with home owners starting to give greater priority to energy efficiency in their buying decisions and new homes on average achieving a B rating, but the cost is deterring many from upgrading existing buildings. The cost of retrofitting to reach a C rating averages nearly £8,000 for those UK homes failing to meet that level, a big outlay in current inflationary conditions, and there are also serious limitations on the workforce available to make such improvements.
Baeli then spoke about the possibilities for retrofitting in the UK owner-occupied sector, where the country’s Net Zero ambitions suggest that energy use for heating needs to fall by two-thirds from the current 150kwh/m2/year, a massive challenge when much of the existing stock is old – for instance, 21% of homes are Victorian in origin. Presenting a number of case studies, she showed that even older properties can gain a huge benefit from effective wall insulation and vacuum-glazed windows, by making them airtight, and by improving ventilation; together, such improvements will help make it possible to use electric heat pumps rather than fossil fuel systems for heating.
Van Heers’ presentation took a continental European perspective on developing new residential buildings, and focused on a test case measuring the carbon performance – both operational and embodied – for houses adopting various more sustainable technologies over their life-cycle. The presentation was striking for its quantitative approach to measuring emissions, with each technology compared in terms of tonnes of CO2 emitted over the 60 years of a dwelling’s assumed lifetime. She particularly stressed the potential from using natural construction materials, including wood for walls and hemp-based screed in the floor, as well as using different energy sources, at the same time stressing that sustainability is not just a question of carbon emissions but also the comfort of residents in terms of air flow and background noise levels, for example.
Dr Kat Martindale joined the panel discussion and audience Q&A, which was chaired by her Savills colleague Emily Williams. Martindale commented that it was likely to be easier for large scale housing investors and social housing owners to retrofit buildings because of their strong purchasing power in relation to suppliers. Along somewhat similar lines, van Heers later suggested that local authorities might arrange for retrofitting services to be available across whole streets.
The cost of upgrading was clearly a major concern among the audience, with Baeli explaining that retrofitting older houses along the lines she had suggested could cost between £80k and £250k, dwarfing the £8k initially mentioned to reach EPC level C. It was however noted that such upgrades could be less expensive when accompanying refurbishments that were already deemed to be necessary, while financial incentives (eg zero-rated Stamp Duty or VAT) could also push individuals in the right direction. But Martindale felt such changes to be unlikely in the current UK political climate.
Tim Horsey