This paper reviews empirical data from evaluations of the influence of residential energy efficiency retrofits on indoor environmental quality conditions and self-reported thermal comfort and health. Data were extracted from 36 studies described in 44 papers plus two reports. Nearly all reviewed studies were performed in Europe or United States. Most studies evaluated retrofits of homes with low-income occupants. Indoor radon and formaldehyde concentrations tended to increase after retrofits that did not add whole-house mechanical ventilation.

The building sector is not on track to lower total greenhouse gas emissions. Given that emissions from the sector represent nearly 40% of global energy-and process-related emissions, this represents a serious challenge to keeping global warming to 1.5oC. The Buildings sector must therefore decarbonize.To support this goal, this report focuses on policy drivers for decarbonisation, and the costs and benefits associated with their implementation.

The review of policies being implemented in China, the EU, India and the US presented in this report has also identified some key challenges that we must address if we are going to realize the mitigation potential of the building sector. Chief among these is the need to improve our monitoring of the impact that our policies are having. Lack of measured and verifiable data on the influence of policies on building energy performance currently hampers our ability to assess and continuously improve their effectiveness.