DEFINING SPECIFIC FAN POWER

The target level shall be defined according to Finnish Building Regulation instruction part D2 (2003) , according to which the SFP (Specific Fan Power) must usually be lower than 2,5 kW/( m3/s). This goes for ordinary ventilation systems. If the controlling of interior air in a building requires other than usual solutions, the instruction allows using a higher SFP-value.

Ventilation systems are usually equipped with heat exchangers, i.e. electricity uses up to 80 % of total ventilation energy consumption. The Finnish Building Regulations (D2 and D3) set new requirements on energy efficiency of ventilation systems in houses. The purpose of SFP- is to in practice describe a method for defining of Specific Fan Power for ventilation systems and air handling units.

In Finland, the supply air of interior air class S1 premises is to be filtered minimum with class F8 filter. In class S2 the requirement is F7. Additionally, close to dense traffic routes and other particle sources (<150 m), filtration rate must be one class higher.

Materials used in bag filters have not developed for e.g. prevention of health problems caused by fine dust. The filtration rate should be increased, but the dramatic cost increase makes it impossible: higher filtration rate requires higher fan efficiency, which again significantly rises costs, as one can see in the examples below.

Example 1.

The supply air filter in an air handling unit is class F7. The exhaust air filter class F5 or F7. The nominal power of the air handling system in the SFP-Guide, Pp. 22-23, is 2,59 kW/m3/s or 2,46 kW/m3/s. Read more

Example 2.

The supply air filter in an air handling unit is class F9. The exhaust air filter class F5 or F7. The nominal power of the air handling system in the SFP-Guide, Pp. 22-23, is 2,69 kW/m3/s or 2,50 kW/m3/s. Read more

Air filters in buildings are usually changed twice a year ”as it has always been done”. The system serves mostly interests of air filter industry and related interest groups. Our opinion is, that filters should be replaced based on the final pressure drop level, defined by the unit supplier.

Quinx-broad surface filters give real estate owners significant savings:

In SFP-values savings average 8% compared to standard filtering intervals of used filters are noticeably longer (not according to calendar)

Reduced costs on maintenance and logistics

The life time of an air handling unit is prolonged due to lower run pressure

Used filter can be utilized as energy waste

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Yrjö Siira