The energy use in the existing residential sector that was built in the second half of 20th century is considered a serious problem across the European Union. The current focus on building energy retrofit provides an opportunity to simultaneously reduce energy use and CO2 emissions of existing buildings. Minimizing energy consumption with energy efficient building design is reasonable. However, the current national legislations and energy performance requirements are not complemented with appropriate requirements and recommendations to secure good IAQ. This dissertation thesis assessed the differences in IAQ and occupants´ well-being and behaviour between original and renovated multifamily residential buildings. The results indicated that renovation of apartment buildings in Slovakia may reduce the quality of the indoor environment in the apartments, especially in the winter season.
When old, leaky residential buildings are upgraded into more airtight and energy efficient ones, the retrofitting effort should include improved has to consider aspects of ventilation in order to ensure sufficient air exchange rates and acceptable and healthy IAQ.