In a recent report by Aecom, 60 per cent of embodied carbon emissions are associated with the sub structure, frame, upper floors and roof of a building. “A deep refurbishment should retain these elements, meaning on average, the carbon footprint of a refurbished building is half that of the newly-built replacement.” 6The frame and structure are also the elements with the longest life span, lasting in excess of 100 years. Laterally, this principle is well-established in a rural context, where Class Q and R Permitted Development rights have allowed for the change of use from agricultural buildings to dwellings and commercial uses respectively, and specifically require that the existing structure is retained. While not necessarily motivated by a low-carbon agenda, this policy has been widely adopted and lots of steel frame barns have been given a new life.
While permitted development rights which allow for change of use from commercial and retail to residential (Class MA) can be divisive, the results can be highly sustainable. On the South Coast, Woldon has recently developed a design for converting a redundant government back-office building to residential, reusing the existing concrete frame and recladding with winter gardens. The winter gardens increase the floor area and provide additional solar shading and insulation to the apartments. Redundant high street retail spaces are also in the spotlight and have huge scope for retrofit innovation and townscape reactivation.
A retrofit brief may focus on changing and upgrading a building’s specification like at Devonshire Mews or expand to include a change in use, like Argal Farm. Both routes have their own merits and scope for innovation in reducing energy consumption and carbon emissions. The motivation behind a capital investment in a retrofit project is, however, likely to involve a range of market factors beyond reducing energy consumption and carbon emissions, for example, improving comfort, convenience and place-making. For owners and managers of existing built assets, there will also be ongoing programmes for periodic maintenance and refurbishment for consideration. The extent and initiation of a retrofit project will be informed by progress through that cycle.