Academicians and professionals in the architecture, engineering, and construction (AEC) field have expressed an increasing interest in sustainability and its application in the development of construction projects, especially with its deemed relationship with lean construction, for the purpose of improving efficiency in the construction processes. Practices framed under the lean philosophy show their potential in reducing environmental, economic, and social impacts during the construction phase, with an increase in the parameters of sustainability in the development of projects.

Cities are crucial sites for achieving socio-technical transitions in technology and infrastructure systems. Raising building energy efficiency (BEE) through new construction or retrofitting holds particular relevance to sustainability transitions since this requires diffusion of new technologies and energy management practices. In pursuit of this, city policymakers around the world are increasingly utilising mixes of multiple policy instruments.

This report is the first report of the ‘Energy Savings 2030’-project which seeks to help the Coalition for Energy Savings to produce a robust and timely input to the 2030 policy discussion. It brings together and summarises recent empirical evidence on costs and benefits of energy efficiency measures. The evidence gap in terms of reliable ex-post data is well known. In the majority of cases results from ex-ante modelling studies inform the debate. The research carried out for this report confirms the persistent gap in publicly available ex-post evaluations of energy efficiency programmes.