Maintenance and benign changes as a sustainable strategy for the refurbishment of historic suburban dwellings

Ritson, James (2020) Maintenance and benign changes as a sustainable strategy for the refurbishment of historic suburban dwellings. (PhD thesis), Kingston University, .

Abstract

The need to reduce carbon emission from the existing built environment is well recognized. However, the advice for historic (pre-1919) homeowners, wanting to reduce the carbon emissions from their homes remains ambiguous at best, and, at worst ineffective and damaging to the historic fabric of their home. This study focuses on the largest group of these dwellings, the pre-1919 suburban dwelling. The study uses a conservation-based methodology as the basis for sustainable refurbishment interventions in the pre-1919 suburban housing stock. The study’shypothesis is that the most sustainable way to refurbish a historic (pre-1919) dwelling is via maintenance, periodicreplacements and benign changes. Benign changes are defined as interventions that have little or no impact on the heritage of the dwelling.The literature review of the study defines what is the heritage of the suburbs and what interventions can be considered benign. It also reviews existing accepted sustainable refurbishment interventions. The literature review shows that the suburbs are a constantly adapting and changingtypology that consists of the majority of the UK’s housing stock. The literature review concludes that a benign intervention is one that has no or little impact on the visual heritage, the fabric heritage and does not change the use or material behaviour of the historic dwelling. The primary research reviews 20 different historic (pre-1919) suburban dwellings. The analysis is based on both computer modelling and live-data and analyses different interventions and their impact on the dwelling’s carbon emissions and energy consumption. Both benign and non-benign intervention are analysed to compare the effectiveness in reducing carbon emissions and energy consumption and the cost to benefit ratio of each type of intervention.The study found that maintenance, periodicrenewal and benign changes (conservation focus) refurbishment has the potential to save between 30% and 50% of carbon emissions and along with this, up to around 40% savings in energy consumption. The study found that the most effective benign intervention was the improvement to the hot water and heating system rather than the more acceptedmethodology of insulation. The study calculated that it would cost between £9 billion and £32 billion to reduce their historic housing stock in the UK's carbon emissions to around 40% to 50%. To reduce the same stock by an additional 30% to 50% (to meet the government target) an additional £61 billion-£373 billion will be needed.A key finding of the study was the tipping point and carbon value of the heritage of the historic dwellings. All the results from the primary research followed a similar pattern when each intervention was plotted against carbon emissions savings from an intervention versus the cost of the intervention. A clear tipping point was found to occurin the range of £2,000 to £7,000 which provides a carbon emission saving of between 30% and 50%. After this point, the cost-benefit ratio decreases significantly meaning that much more money is needed after the tipping point to reduce the carbon emission further(in comparison to before the tipping point). The study goes on to define the carbon value of the heritage of the historic dwelling in the following equation: The triple bottom line carbon value of heritage = Target carbonemissionreduction - Total carbon emission reduction of the benign changes which are financially viable

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