Efficient operation and maintenance of ventilation systems

Tasks for operation and maintenance staff

• Check electricity consumption and operating time. Continually calibrate the operating time in line with demand during the year. As a general rule, ventilation systems should be started up immediately before the first person uses a room, and should be turned off when the last person has left (e.g. use a time switch).
  > Read about operating times, CO2 and air quality (external link only in Danish)
• Check the filter once a week, and replace it if the pressure loss is too great.
• Check the belt drive between the motor and fan on a weekly basis. When changing the belt, choose a high efficiency one.
• Check the settings for the required temperature, including the supply temperature.
  > Read about supply temperature (external link only in Danish)
• Check that the damper closes when the system is switched off on a weekly basis.
• Check that the condenser outlet on any heat recovery unit is not blocked, and clean as necessary.
• Check that the system is not dirty, and clean as necessary.

Tasks for ventilation firms

• Carry out an annual certified VENT check of the system by checking the air volume, temperature conditions, electricity consumption, etc., and monitor the recommendations.
• Carry out one annual or half yearly service check of the system.
• Evaluate the key indicators, possibly together with staff responsible for operation and maintenance. Compare current and previous figures, and compare these with other ventilation systems. If there is a large variation, then investigate the reasons.

> View list of ventilation firms (external link only in Danish)

Operation and maintenance staff - what you need to know

Electricity consumption
Ventilation typically accounts for 10-40% of a building’s electricity consumption. It is therefore important that the efficiency is as high as possible so as to avoid unnecessary electricity consumption and costs.

The amount of electricity consumed depends on:

• The air volume supplied and extracted.
• Efficiency of the complete system, which depends on the pressure loss through the filter, ducts, connectors, air supply and extractor mountings etc., and the efficiency of motors, fans and belt drives.
• Operating time for the system, i.e. when it is switched on and off.

Air volumes
It is important that air volumes are suited to your needs. In many buildings air volumes are much greater than required for long periods. However, there are also some buildings in which air volumes are too low, resulting in a poor indoor environment. In these cases air volumes should be increased, with greater consumption of electricity as a consequence.

If air volumes are too great relative to the requirements, there are considerable savings to be made by reducing the volume. For example, a 20% reduction in air volumes results in electricity savings of 44%. This is due to the fact that, when the air volume falls, the electric motor which transports the ventilation air works considerably less.

> Read about recommended air volumes.

Efficiency
Changes to the system should be made if the efficiency of the fan, motor, any other related components and a reduction of the pressure loss are to be improved.

Operating time
The operating periods ought to be recorded and checked frequently with an electricity meter system, which is installed if you use the Trust’s ventilation package. In this way you can regularly set the operating period to suit demand.

Reduction in the operating time provides electricity savings that equate to the reduced time. For example, 10% less operating time results in electricity savings of 10%.