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.

Around the world, engineers, architects and policymakers have been exploring ways to deliver highly efficient buildings whose reduced energy demand is satisfied by clean, renewable energy. Building off of the broader concept of a green or sustainable building, the concept of the “net zero building” focuses on the energy dynamics and performance of the building. And as policymakers and leaders align toward the net zero concept, the focus on achieving deep energy efficiency has centered on integrated technologies as well as ways to connect buildings to the natural environment.