The UK government's Clean Growth Strategy unambiguously described the decarbonisation of heat as the UK's greatest policy and technical challenge in meeting our carbon targets. Maximising the potential for energy efficiency in the existing domestic stock is critical to the low-carbon heat transition. Good information exists on the technical potential for energy efficiency measures in the UK stock, however, a lack of knowledge about current stock conditions and in-use factors places considerable uncertainty on how much of this technical potential is achievable in practice. This study uses data from the fifth carbon budget (CB5) policy projections and updates the in-use factors using measured data from the National Energy Efficiency Database (NEED). This results in a 26% shortfall by 2035 in the anticipated energy savings through cavity, solid wall, and loft insulation compared to what is assumed in the CB5 projections. This will have costly implications for meeting future carbon budgets. Risks and policy implications are discussed. The practical potential for energy efficiency measures beyond cavity, solid wall, and loft insulation is explored.

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By 2050, UK plans to create 'low carbon society'. To meet this ambitious target, UK's heating sector must be completely decarbonized. The identification and deployment of low carbon heating sources is thus an urgent policy and research priority. Recovering heat from sewage wastewater is relatively new and attractive option as it can help UK move towards its climate change targets while decarbonising the heating sector & reducing the reliance on fossil fuels. In the domestic context, wastewater is normally discharged at higher temperature than ambient (a carrier of heat/ thermal energy) losses its energy to (ground) environment before it reaches to WWTP. Recovering this heat from wastewater could be a considerable source of energy, revenue and is environmental friendly as it results in the reduction of GHG emissions, resource conservation and in increase share of renewable energy. In last decade, many cities around the world have successfully implemented wastewater thermal energy recovery but UK is lagging behind. Pilot project such as in Scotland is leading the way, but further research is needed to build the evidence base and replicate the concept elsewhere in UK. The Home Energy 4 Tomorrow (HE4T) project at London South Bank University (LSBU) was created to address this evidence gap. The project objectives include sizing the heat potential recoverable from wastewater at designated sites. The current paper forms part of the HE4T project and the second in series of output on wastewater heat recovery in UK. In this paper we present some initially measured data, variations in wastewater temperature and flow, steady state and dynamic model results wastewater temperature and the potential heat recovery of the designated site. Early results, their limitations and possible routes to address these limitations are discussed along with policy implications for UK heat strategy.

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Any attempts to limit the impacts of climate change must maximize the potential for energy efficiency in existing dwellings. Retrofitting the existing stock of aging and inefficient dwellings is a challenge on many fronts. A number of programs have been put in place to encourage domestic retrofits by reducing barriers such as the upfront costs and access to capital. While many such programs are delivering positive results, there is much uncertainty regarding what constitutes success, as well as the long term cost effectiveness of various approaches. Geographic, demographic, and programmatic differences frequently cloud the ability to make comparisons across programs. This work examines a case study from Efficiency Maine in the United States, in which a grant program transitioned to a financing program. The grant program was highly popular and delivered significant energy savings, but used considerable public funds. The financing program reaches fewer homeowners, but delivers larger retrofit projects per homeowner, and leverages private investment with smaller public expenditures. Which of the two programs can be considered more successful? This work explores the methods of assessing this question and offers the author's perspectives.