The existing residential building stock accounts for a substantial portion of worldwide energy consumption and greenhouse emissions. Improvements to the thermal performance of existing buildings is a vital activity to mitigate climate change, and often has additional benefits in the form of improved comfort, health and well-being for occupants. Despite the extensive body of literature in this area, it remains a difficult task to assess the performance of retrofit packages in occupied residential buildings.

While household mould growth has been increasingly highlighted in response to its adverse health outcomes and building management burden, studies are reviewed respectively from perspective of epidemiological survey, or building technology. This paper thus presents a literature review to address the building environment and mould exposure in homes, including the mould growth and exposure characteristics, interaction with building features, design requirements from current standards.

This study presents three cost-optimal calculations. The overall aim is to provide a deeper analysis and to provide additional guidance on how to properly implement the cost-optimality methodology in Member States. Without proper guidance and lessons from exemplary case studies using realistic input data (reflecting the likely future development), there is a risk that the cost-optimal methodology may be implemented at suboptimal levels.