Report reveals many ventilation systems run badly

1/3 of all ventilation systems in schools do not ventilate well enough
The Trust’s survey of schools revealed that 1/3 of all ventilation systems in schools did not ventilate well enough. Headaches, mucosal irritation, tiredness and a reduced ability to concentrate were typical results. These affect the whole working environment, general well-being and productivity and can lead to extra days off sick. Children and students in daycare facilities learn less in such environments.

The check-ups revealed

• 1/3 of the systems did not meet the requirements for air volumes and energy efficiency specified in the Danish Building Regulations (BR 95).
  
• Half the systems ventilated more than 50% more than they needed to, in relation to the requirements in BR 95.
  
• 1/5 of the systems ventilated at more than twice the level in relation to the requirements in BR 95.
  
• 3/4 of the systems ventilated at night (between 22.00 and 07.00).
  
• Approximately 1/5 of the systems consumed over 30% of their electricity during the night.
  
• Approximately 1/3 of the systems consumed over 20% of their electricity during the night.

Typical opportunities for improvements

• On average, the systems in the survey used 16 kWh per m2 per year. Savings of 1/3 can be made if the air volume is reduced in line with the fresh air requirements.
  
• Reduce the air volume to suit demand, by replacing pulleys, drive belts, etc. 
  
• Replace fans with efficient low energy fans.
  
• Fit a time switch to start and stop the system based on the ventilation demand. This can reduce the electricity consumed by the system by 40-50%.
  
• Consider installing movement sensors to control when the system starts and stops.
  
• Consider installing CO2 sensors in classrooms to monitor the efficiency of the ventilation, and possibly to control the operation of the system.
  
• Reduce the pressure loss in the ducting system, components, and fan intake and outlet.
  
• Replace components and units with high efficiency types.

Reasons why ventilation systems run badly

• Ventilation requirements vary when the number of people in rooms changes frequently during the day and over a year.
  
• The conditions in rooms have changed since the system was configured, without the system being reconfigured in line with the new conditions.
  
• Check-ups and service of the system are carried out infrequently.
  
• There is generally too little awareness of the system.