Apartment building pictured from the ground up

Poor indoor air is relatively common. Studies show that more than half of residents in apartment blocks suffer from indoor air problems. When looking at the apartment building stock in more detail, the problem is especially true for older houses with either gravity or mechanical exhaust ventilation. 

In general, the problem is insufficient ventilation. In newer properties, the problem is smaller, because ventilation has been increased in building regulations over the years. There is a mandatory requirement for heat recovery in new properties, which was not initially available in existing properties. Because ventilation is the single biggest cause of energy loss, efforts have been made to keep it low – and this is causing problems.


The purpose of adequate ventilation is to keep buildings and people healthy. Its function is to remove moisture and impurities from the property. Ventilation is designed to move air from clean rooms to dirtier and it typically exits from the kitchen and washrooms. In apartment blocks and terraced houses, the company is responsible for the ventilation. Here, too, the government and the property manager must be aware of their responsibilities. In old apartment buildings, ventilation is typically at half power for 16 to 18 hours per day and at full power for 6 to 8 hours. However, there have been houses where ventilation has been on for only 6 hours a day to avoid wasting energy. They are sailing through dangerous waters, for energy savings should never be made at the expense of the building and the health of the occupants.


Our HybridHEAT system, which we have developed for houses with mechanical exhaust ventilation, offers the best possible heat recovery and a variety of ventilation control options to improve indoor air quality. If your property has original windows, you may want to consider purchasing modern replacement air windows. This will improve the supply of replacement air to the property and thereby increase the amount of ventilation.

The author is the Managing Director of HögforsGST

Antti Hartman

Strategy & Business Development Director

+358 400 738 325
antti.hartman@hogforsgst.com