New solutions bring a breath of fresh air


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 square metre.

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.

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