How to ensure occupant comfort and satisfaction through deep building retrofit? Lessons from a Danish case study

The pace of building retrofit is expected to increase significantly in the coming decade if the European Union is to meet its ambitious climate targets. This study explores successes and challenges with current retrofit efforts, with focus on indoor environmental quality and occupants’ satisfaction with the technical installations. A survey, indoor environmental monitoring and semi-structured interviews were carried out in a Danish social housing area undergoing a deep energy retrofit. The retrofit considerably improved winter thermal comfort and indoor air quality, which was a great source of satisfaction for the occupants. Overheating was however identified as an important concern in summer. The mechanical ventilation units suffered from faults which caused discomfort, in particular dry air, noise and draft. Occupants lacked knowledge on ventilation and manual control over it, which led a share of them to mitigate discomfort in alternative ways, by obstructing diffusers or disconnecting the units. To avoid the risks linked to such behaviors, new retrofit efforts should pay particular attention to user-friendliness of technical installations, clear communication of technical information to the residents and a close monitoring of the installations’ performance and occupants’ satisfaction after move-in.