- Increasing urban density can be achieved through considerate expanding of existing buildings, as long as this does not overwhelm the existing structure and structural integrity. Refurbishing and retrofitting should be the priority consideration over new builds, unless the whole-lifetime carbon of a new building is similar to or less than the retrofit. Climate change, resources and waste are the largest environmental factors, however, retrofit assessment must be a combination of environmental and non-environmental factors.
- Public housing must be well-designed, built, maintained and loved. Where public housing is faulty, dangerous, poorly built, difficult to manage, difficult to let, unloved by residents or out of scale, it must be rethought, rebuilt and optimised. Local authorities should lead this process, which requires a nuanced response and combination of retrofitting and demolition to improve public land.
- To enable truly sustainable development, an analysis of full lifecycle carbon emissions is necessary. This includes emissions caused by the materials, pre-construction, construction, operation and end-of-life phases of a building. These emissions can be compared and weighed up against different retrofit, demolition and newbuild options. Resources such as the GLA’s Whole Life Carbon Assessment guidance can be used to assess a building’s carbon impact, setting out 16 Whole Life Carbon principles.
- To make retrofit efforts as sustainable as possible, a combination of assessment tools can be used to analyse and tailor the retrofit approach. These assessment tools can include carbon calculators to quantify emissions from construction materials and processes, fabric analyses to establish the makeup and condition of a building, environment analyses to understand how buildings behave in their surroundings, and building information modelling (BIM) software to bring all the information together. This information can be utilised alongside retrofit decision-making toolkits for optimal outcomes.
- Retrofit-first policies should be introduced in local plans to strengthen the review of demolition and retrofit applications going forward. These policies can define different levels of retrofitting measures while making it easier and more efficient to evaluate public benefit and environmental impact.
- Hybrid masterplans combining elements of retrofit and new-build solutions on the same site can function as a sustainable form of development and revitalisation. Existing structures can be retained while enlarging their footprint and extending out from the existing building. New buildings can be added to densify the site and integrate into the local context. In the process of evaluating development approaches the existing building, retrofit option and newbuild option can be compared.
Simon Sturgis Architect and Founder, Targeting Zero LLP
Paul Karakusevic Founding Partner, Karakusevic Carson Architects
Arun Rao Interim Principal Policy and Programmes Officer, Environment Team, GLA
Geoff Rich Partner and Director of Heritage & Creative Use, Fielden Clegg Bradley Studios
Ian Poole Senior Whole Life Carbon Officer, LB Westminster
Phil Catcheside Partner, Residential Sector Lead and Certified Passivhaus Designer, Hawkins Brown
