There are indications that energy-retrofitted buildings can create risks for indoor environmental quality (IEQ) and therefore for health and comfort of occupants. A review was conducted to identify and verify those risks, within three themes: building envelope, heating, ventilating and air conditioning (HVAC)-systems, and occupants. Publications from the last five years in major peer-reviewed journals from different fields (energy, buildings, indoor air, social sciences) were found by using a variety of keywords (health effects, occupant behaviours, energy-efficient retrofitting, etc.).

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.

In 2009, the European Union adopted high-level goals for renewable energy, energy efficiency, and greenhouse gas reductions with targets set toward the year 2020. This was followed in 2012 by adoption of the Energy Efficiency Directive (EED) (2012/27/EU), which included as a major component a requirement for Member States to create Energy Efficiency Obligations Schemes (EEOSs) on energy companies or equivalent alternative measures, and those provisions have now been in effect for three years.