Energy Efficiency EGM

Published date: 03 July 2020
Last modified date: 03 July 2020



Climate change is one of the most challenge of our era, mitigating its effect is one way to fight it. The adoption of energy efficiency (EE) solutions has a great potential to reduce energy demand and consumption, thereby contributing to mitigate the reduction of global CO2 emissions. Over the last decade, there has been an increasing global interest in EE. In 2019 alone, USD250 billion were invested in EE, with numerous programmes, policies and projects implemented to foster the adoption of EE technologies and practices among different end users. By searching both academic and grey literature, we have mapped a total of 283 impact evaluations (IEs) and 16 systematic reviews (SRs) related to the effects of energy efficiency (EE) interventions at the household, public institutions, and business level around the world. The EGM reveals clusters of evidence and key gaps where limited or no evidence exists and more research is needed.

Main findings

  • Despite the increasing number of IEs published each year, there are some absolute evidence gaps among interventions and outcomes evaluated
  • The most commonly evaluated interventions were: the introduction of systems to monitor energy consumption (66), the direct provision of EE technologies and services (53) and the implementation of education campaigns to raise awareness regarding EE (40).
  • Most of the studies measured net savings of energy consumption (204). Other common outcome measures included changes in the adoption of EE behaviours (85) and changes in awareness and attitudes (67). Only a few studies measuring socio-economic outcomes, such as health and well-being or changes in buildings’ values.
  • There are seven intervention categories with no or few studies, which represent ‘absolute’ gaps.
  • There is a geographical gap as studies skewed toward HICs (75% of the included studies).
  • Of the 16 SRs included, none has been rated as of high-confidence level.
  • There is also an important gap in studies at the end-user level: 86 per cent of studies evaluated interventions implemented at the household level, whereas only nine per cent were at the level of businesses, and 5 per cent were implemented among public institutions.

Implications for policy, programming, research investments 

Implications for policy and programming
Decision makers and programme implementers can use this map when designing or implementing an intervention by taking into consideration the existing rigorous evidence, learning useful lessons from completed research and avoiding duplication of efforts. Hence, we suggest the following:

  • When commissioning a new EE intervention and the map shows no existing evidence for that intervention, or evidence is lacking in that geographic area, consider including an IE when implementing the intervention, following the research implications presented in the next section.
  • If there is evidence available for the intervention of interest, consider the results from medium-quality SRs (with some caution because they are not high-quality), and if useful, consult low-quality reviews to learn about the characteristics of the evidence base.
  • If no SRs are available, the findings from primary studies can be useful for programme design. However, because the results of one or several studies could not be generalised, they should be treated with caution. In using evidence from a single case evaluation, both IE experts and specialists in the sector should be consulted to assess the transferability of results to different contexts.
  • If there is a cluster of evidence on the intervention of interest shown in the EGM and no high-confidence SR exists, as in this map, consider commissioning an SR, ideally following guidelines that ensure high-confidence level of the results, as presented in the next section.

Implications for future research
Despite the challenges in conducting experiments to evaluate the interventions and contexts discussed herein, we found numerous RCTs and quasi-experimental studies. However, there are still many evidence gaps, as discussed in Section 5. When commissioning or designing a new evaluation, we suggest that researchers and funders consider the following:

  • Conducting an IE for one of the following intervention categories: capacity building to develop EE skills, technical assistance to support those who want to switch to an EE technology, bank lending reserved for EE investments, and home appliance credit to support the purchase of more efficient appliances.
  • Applying the most rigorous experimental and quasi-experimental methods (Section 3.2.4 of the report) that suit the available data, intervention type and context.
  • Applying guidance from the Collaboration for Environmental Evidence, Campbell, and Cochrane, as well as reporting standards like PRISMA2020 or ROSES (or equivalent) to conduct high-confidence level SRs.
  • Evaluating more EE interventions in L&MICs.
  • Evaluating EE interventions that target firms, industry or public institutions.
  • Measuring both energy-related and socio-economic outcomes.
  • Including cost data, a cost-effectiveness analysis, a cost-benefit analysis or a return on investment analysis in the evaluation.
  • Making use of mixed methods approaches to combine qualitative and quantitative evaluations for more holistic overviews of what affects intervention effectiveness.
  • Reducing evaluations’ costs, considering efforts made to standardise methods for evaluating EE projects and programmes, and ensuring consistency and common approaches (such as the international performance measurement and verification protocol).
  • Making new evaluations publicly available so that everyone can learn more about the effectiveness of these interventions.
  • Recognising the necessity of a ‘living map’ or an update of this map in the near future, because the effectiveness evidence on EE is expected to grow rapidly.

Original map publication date: 22nd of April 2021
Current map date of publication: 22nd of April 2021

Online map citation:
Berretta, M, Zamawe, C, Ferraro, PJ, Haddaway, N, Minx, J, Snilstveit, B and Eyers, J, 2021. Mapping energy efficiency interventions, 3ie. Available at:

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