Understanding carbon in the historic environment : scoping study

The UK is committed to becoming carbon neutral by 2050, necessitating fundamental changes in energy sources and end uses over the next three decades. As climate change mitigation policy continues to grow in importance, securing and communicating opportunities to improve the energy efficiency of the English historic building stock through low carbon refurbishment is critical to its long-term survival. To date, regulations and policymakers measure the carbon emissions of buildings based on operational energy use only, ignoring the embodied carbon benefits of reusing the existing structure. Very few studies have considered the whole life carbon of historic buildings. This study improves our understanding through the use of life cycle assessment and offers a more complete measurement method of all carbon emissions, both embodied and operational. The objective was to identify suitable methods and tools for the assessment of the life cycle carbon emissions of different concept-stage energy efficient refurbishment designs for historic buildings, and to assess the life cycle carbon emissions of two refurbishment case studies. This sample size is small and cannot be used to paint an overall picture of the potential carbon savings of refurbishing existing buildings for improved energy efficiency, however it demonstrates the need for more empirical data to be gathered and analysed. Heritage bodies, the development sector and building owners could contribute to this process, but it will also need to be driven by a revision of existing policies and regulations. Based on a review of current research and industry best practice in the field, a detailed methodology was developed for this study to assess the life cycle impacts of different concept-stage designs for historic buildings including refurbishment and demolish-and-replace. This methodology was applied to two completed energy refurbishment projects: a one-off conversion of a chapel for residential use; and the refurbishment of an end- of-terrace Victorian house similar to many buildings in England. These case studies analysed the life cycle emissions of the actual refurbishment works that were carried out at each dwelling and their projected the long-term operational emissions. It was not the intention of this study to verify the suitability of these works as much guidance on heritage and moisture-related concerns has already been published by Historic England and other reputable sources. The findings highlight that the energy efficient refurbishment of historic buildings is necessary to achieve performances similar to buildings. It was also found that existing regulations, which consider operational emissions only, are misrepresentative of the total carbon emissions of demolition and new construction. In the case of the New-build, the omission of embodied carbon emissions would underestimate the total emissions by nearly 30%. The prioritisation of refurbishment over demolition is inherently sustainable, as the waste of many materials with carbon already embedded in them would be avoided. With a view to the 2030 and 2050 policy targets, the refurbishment of the Victorian terrace was found to achieve the best carbon reductions of all options considered. The life cycle carbon emissions of the Victorian Terrace Refurbishment are less than those of the New-build until approximately 60 years from now, at which point they remain competitive though slightly higher. As it would not be feasible or preferable to demolish and rebuild the entire existing building stock, this emphasises the comparable energy performance that can be achieved with historic buildings if they are refurbished with improved energy performance in mind. Historic building refurbishment was also found to achieve the best economic performances in terms of marginal abatement costs and savings-to-investment ratios. Ideally, life cycle assessment will be done at the concept-design stage to guide the decision-making process, rather than after the fact. This research, however, did not identify a single one-stop-shop tool suitable for the calculation of life cycle analysis of refurbishments at the concept-design stage, but tools have been recommended which could be adapted, combined and/or extended to develop a suitable tool for refurbishment projects, which would make the process of LCA faster. A number of recommendations are made based on this study, which include: developing associated decision support tools such as computer applications; developing an ongoing data collection and analysis programme; developing practitioner guidance which addresses.