To build or not to build? Arguments abound over green claims
Two landmark mid-century buildings are set to be demolished and replaced with tower blocks. Some claim they would be better refurbished to avoid the ‘embodied carbon’ of a new build, but others insist starting again is better for the climate. explores the
LAST week Bristol City Council gave planning permission to developers to knock down the old Debenhams building in Broadmead, and replace it with 502 apartments split between several buildings, the tallest reaching 28 storeys. There are also plans to replace the Premier Inn on the Bearpit.
Debenhams was built in the 1950s, and across the country department store buildings are often too large for companies today. Instead, smaller shops and cafes will be built on the ground floor of the new buildings, along a new street running through the centre of the site.
Old buildings take much more energy to heat whereas newer ones are often much more energy efficient, saving on carbon emissions related to heating buildings, notably from burning natural gas. On the other hand, “embodied carbon” from replacing buildings causes a huge one-off increase in emissions, as concrete and other materials require a lot of energy to produce.
According to a factsheet from the University College London, embodied carbon refers to all the CO2 emissions from producing materials. The factsheet says: “The embodied carbon of a building can include all the emissions from the construction materials, the building process, all the fixtures and fittings inside as well as from deconstructing and disposing of it at the end of its lifetime. Building a new replacement requires more materials and energy, creating more embodied carbon.”
But whether that was outweighed by the benefits of building new energy-efficient homes was a key matter for councillors on the development control A committee to decide on Wednesday. They heard from both sides of the debate about refurbishing versus replacing.
Tom Brown, a chartered environmentalist leading on sustainability for the Debenhams scheme, said: “The building will achieve a 50 per cent reduction in carbon building regulations, and a 42 per cent reduction in residual CO2 emissions, double the planning policy target.
“This will be achieved with a high efficiency building fabric, connection to the district heat network, and provision of onsite solar PV. This is a highly sustainable development, which will positively contribute towards the council’s net zero commitments.”
According to council planning officers, the department store has “come to the end of its useful life”. There is less demand from retailers for large department store buildings, and several large stores have closed recently.
Developers explored adapting the building, but this would be a challenge due to limited daylight inside. Part of the building would need to be demolished in order to provide enough daylight to the flats.
Several members of the public spoke against the plans to replace Debenhams, due to the height of the new buildings, and also the loss of the historic architecture and embodied carbon.
Stephen Wickham, from the Bristol Conservation Advisory Panel, said: “The existing landmark building, with its impressive and sophisticated fivestorey facade should be identified as a non-designated heritage asset, in recognition of its clear historic significance. It should be refurbished and repurposed, thus avoiding the carbon cost of demolition and reconstruction.”
A similar argument was heard in the council chamber a month ago, when the same councillors narrowly voted to approve plans to knock down the Premier Inn on the Bearpit, and replace the hotel with two apartment towers, the tallest also reaching 28 storeys. The development control A committee met on March 6 to debate whether to grant permission for the Premier Inn scheme.
Matthew Montagu-Pollock, opposing the scheme, said at the time: “We’re filling the centre with 28-storey tower blocks. The embodied carbon cost per square metre will typically be horrendous.
“A more realistic option would be to repurpose the existing building as housing.”
But Zeta Stebbings, a carbon specialist working on the project, said: “We’ve used the most robust industry software tools to assess the lifecycle carbon of the building, including an option to retain the existing building. The results of this assessment are emphatic.
“They show that retaining the existing building would produce three times the carbon over its operational lifetime, compared to replacing the building with a highly energy efficient new building.
“Structural studies show the existing building has suffered significant concrete degradation, and has reached the end of its 55-year life.”