Journal article
Rethinking retrofit: Relational insights for the design of residential energy efficiency policy
Jan 2025
Author: Lucas Boehlé, Energy Efficiency Analyst, International Energy Agency (IEA)
In this blog, Lucas Boehlé gives an overview of our recent webinar ‘Reducing Energy Demand – A UK Success Story?’. He sets out the IEA’s analysis of UK energy efficiency gains from 2010 to 2019 – the highest in the G20 – and reflects on wider lessons for the global transition to net zero.
This was the key question during the joint IEA-UKERC-EDRC webinar on March 20, 2025. I kicked things off with a quick overview of the IEA Energy Efficiency 2024 report, which takes a close look at the UK case. Then, Professors Nick Eyre (University of Oxford) and Karen Turner (University of Strathclyde) shared their thoughts on the trends, followed by a lively discussion and audience Q&A.
Energy efficiency is usually measured by how much energy a country needs to produce a certain amount of economic output (energy intensity); lower energy use for the same output means better efficiency. At the 2023 United Nations Climate Change Conference (COP28), countries agreed to aim collectively to double the global average annual rate of energy efficiency improvements by 2030. In 2022, the global rate of progress was around 2%, so doubling implies a progress rate of 4%. The IEA Net Zero Emissions by 2050 Scenario also sees global energy intensity improve by around 4% each year between 2022 and 2030.
According to our analysis, the United Kingdom was the only G20 country to average more than 4% annual improvement in energy intensity over the decade 2010-2019. That is why we looked at the country in a bit more detail. Several factors contributed to the UK’s progress, including policy-induced gains in efficiency, structural shifts in the electricity mix, milder than usual weather in 2019 reducing heating demand, and structural changes in industry towards higher-value-added activities.
Between 2010 and 2019, the UK’s total energy supply fell by 17%. Coal use dropped by 80%, while renewable electricity generation grew fivefold. These changes helped cut supply-side energy intensity, since coal and other thermal power sources waste a lot of heat. Final energy use also fell 9% from 2010 to 2019, while the economy grew 19%. Residential energy use decreased 21%, despite a growing population and more homes. Industrial energy demand declined 16%, partly due to reduced steel production. Transport energy use stayed flat, even though people travelled more.
Further gains may have been possible with stronger energy savings in transport and if high-impact buildings retrofit programmes had been maintained. Electrification of transport and heating also offers opportunities for a step-change in efficiency compared with what was possible in the past. For instance, impressive reductions in gas use were made through condensing boiler efficiency requirements, contributing to a fall of residential gas use of 30% between 2010 and 2019. There was, however, only a limited shift towards electrification of heating with heat pumps. This suggests that significant efficiency potential remains, even for countries with strong historical progress.
Prof. Nick Eyre discussed how factors like warmer weather and the phase-out of coal might have influenced the results. But he also highlighted the real impact of policies, such as the UK’s insulation efforts – especially before 2013 – and strong appliance regulations in the European Union. He believes hitting the 4% target again is doable, but only with strong policies in place.
Prof. Karen Turner noted the United Kingdom still has lots of efficiency potential, especially in electrification. She pointed out that upfront costs remain a barrier, particularly for lower-income households, and that there are also important challenges, such as shortages in skilled workers. This is an area where policy can really make a difference.
The UK case shows there has been real policy-driven efficiency progress that can provide important lessons for other countries. Accelerated implementation of new and existing efficiency policies is required, however, to reach those progress rates again and sustain them.
The next big international event to discuss global progress is IEA’s 10th Annual Global Conference on Energy Efficiency in Brussels on 12 and 13 June 2025. The event comes at a pivotal moment. Governments agreed at COP28 to double the global rate of energy efficiency improvements by 2030. Achieving this goal is critical if the international community is to bring about the secure, affordable clean energy system that can meet our shared climate goals. But progress must accelerate rapidly if the goal is to be met. The 10th Global Conference provides the key forum in 2025 for Ministers, CEOs and senior leaders to come together to chart a path towards achieving the doubling goal.
We have also begun working on the next report, Energy Efficiency 2025. We very much welcome feedback from efficiency experts around the world to bring their ideas, data, and case studies that they believe can contribute to the report.
Lucas Boehlé, IEA
Please reach out to Lucas.BOEHLE@IEA.org for more information.