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MPhil in Engineering for Sustainable Development

global challenges, engineering solutions

Studying at Cambridge

Philippe Bernier

Retrofit for the Future: Existing Homes and Building Rating Systems

With the ratification of the Climate Change Act, the UK Government agreed to a 26% reduction in greenhouse gas (GHG) emissions by 2020 and an 80% reduction by 2050.  Britain’s 26M existing homes account for 27% of total UK GHG emissions. Given the lowbuild rate for new homes, today’s homes will comprise at least 80% of the 2050 housing stock. Therefore, it is essential that significant improvements are realised to existing homes if the UK is to meet its sustainability objectives.

 

With owner-occupancy levels in excess of 70% and a highly fragmented home construction and renovation supply chain, a focal point is needed to align stakeholders and measure progress towards targets. Well-developed standards can align efforts to achieve consistent and quality results. While a growing number of building rating systems (BRS) assess and certify the ‘green’ credentials of new buildings, no comprehensive standard is yet available to guide and rate improvements made by existing homeowners.

 

A new BRS for existing homes was developed, and six leading retrofit case studies from different cuts of the UK housing stock were successfully assessed and rated. Performance of the BRS in turn was critiqued, and recommendations made for its improvement. Cost- and carbon-effective priority retrofit activities were also investigated based upon case study findings and further research.

 

To achieve aggressive GHG emissions reduction and other sustainability objectives, a coherent Government strategy and action plan are urgently needed to address existing homes.  Government should create and adopt a BRS as a policy centrepiece, with escalating mandatory performance levels in energy and water efficiency to drive improvement and overcome market failure. This BRS would be used to rate existing homes, galvanise stakeholders around a common framework, and provide long-term visibility to the marketplace. It must be integrated with existing building regulations, planning mechanisms, incentive programs, and assessment requirements such Energy Performance Certificates.  Barriers and solutions to rolling out such a tool are also presented.