VTT has developed more effective air filter solutions capable of removing
90% of ambient air particulates. The new filter solutions can be added to
existing ventilation systems without resorting to changes in structure or size.
Particulates are the cause of over one thousand premature deaths in Finland
every year. Exposure generally occurs in indoor spaces. The most serious indoor
air problems are caused by damp and mould. According to the Ministry of the
Environment, 600,000–800,000 Finns are exposed to these impurities every day.
The buildings in worst condition are day care centres, schools and hospitals.
According to the Parliamentary Audit Committee report of January 2012, the level
of health-related costs arising from damp and mould damage is in the order of
EUR 23–953 million.
Development of traditional ventilation systems can bring considerable
improvement in ambient air quality. Equipment solutions consist of a central
ventilation unit and air filtration solutions for supply air terminal devices
within the rooms. VTT's solutions entail no alteration to the basic structure of
ventilation systems, nor add significantly to their size, air flow or energy
consumption. Annual usage costs are estimated to be no more than 10 euros per
The new filter solutions also reduce the amount of ambient particulates by
10% compared to the current level, together with efficient removal of harmful
ozone, and help in relieving any damp and mould problems.
The filter solution for the ventilation unit passes supply air through a
combined electret fibrous filter and active charcoal filter, where the filtering
effect is enhanced by means of electrostatic charging. Air supply units are of
the so-called 'active chilled beam' type to which an indoor air particle
filtering solution has been added.
The solution for the air supply unit consists of a section for collecting
particles entering the unit and an externally fitted, electrostatically charged
unit for particles passing the underside of the supply unit's base plate. Poor
quality air in the air supply unit is cleaned on the recycling principle, where
the most important variable affecting air cleanliness is 'effective air flow'
(the product of collecting efficiency and air flow or, in other words, the
volume of air that is free of particles).
The operability of both solutions has also been tested by VTT in practical
environments, including offices. According to the measurement results, a 90%
reduction in the particulate content of indoor air is a realistic target. The
result for the reduction in ozone content was approximately 75%.
The next step is testing in larger projects for the air quality that can be
achieved using air supply unit solutions in office and school environments,
among others in the Helsinki metropolitan area. The principal funding agency for
this project is The Finnish Work Environment Fund.