While energy retrofitting can alleviate some problems with the indoor environment, it has simultaneously introduced new problems. Research has recently revealed a shift in challenges regarding the thermal environment in Danish houses over the past decades. A survey by Realdania and Bolius shows that houses built before 2000 typically have problems with draught and cold, whereas houses built after 2000 tend to have the opposite problem – overheating.
This problem is also current in energy-retrofitted houses. Here it usually occurs due to a highly sealed, insulated façade – a renovation procedure that often requires installation of a mechanical ventilation system.
So-called passive solutions, such as natural ventilation systems, typically control heating and cooling and thus have an impact on the indoor environment and thermal conditions. At the same time, they can minimize energy use. However, only limited research has focused on the potential of using passive solutions to improve the indoor environment.