The Climate Change Committee (CCC) commissioned University College London to review and update the cost and savings assumptions related to energy efficiency measures in homes, including an increased focus on in-use performance. The updated assumptions incorporate in-use measured data from the National Energy Efficiency Data-framework (NEED) alongside the latest evidence published by Government on the costs of measures. Over 150 datasets, studies and published reports were considered in total. The resulting assumptions were used as an input to Element Energy’s analysis ‘Development of trajectories for residential heat decarbonisation to inform the Sixth Carbon Budget’, focusing on existing homes. The final energy efficiency assumptions used are set out here.
2. Key recommendations
- The most significant energy savings across different types of home are generally associated with wall insulation. While relatively easier to implement, measures such as draught-proofing and hot water tank insulation can collectively achieve considerable savings when combined and implemented properly.
- The results of an exercise to compare costs and savings assumptions for the Fifth and Sixth Carbon Budgets suggest that estimated savings for solid wall insulation and double glazing have generally reduced, with costs generally identified to be higher for internal wall insulation, floor insulation and double glazing. Despite achieving variable energy savings, costs associated with glazing measures are in some cases comparable to those for the most expensive insulation measures.