Commercial Air Handling Units (Supply and Extract Systems)

Building ventilation systems are designed to control the environment within areas of a building, they are designed to deliver clean fresh air that can be heated up or cooled down to control the building temperature and humidity dependent on the type of build and its use.

Ventilation systems generally consist of supply and extract fans which convey the air flow throughout a building with the use of fabricated steel duct work, the air flow will be past across banks of air filters to clean the air before it is conditioned by heating or cooling.

The conditioned air flow will pass in to the building through controlled and balanced air dampers, within a building it is the case that to prevent stale odours from collecting, the used air flow is extracted from rooms and returned to the pant room to expelled to outside.

The extract air flow before it leaves the ventilation system, can be passed across a heat exchanger, this will then be used to preheat the incoming fresh air, this is a way to provide some heat recovery and reduce energy consumption and building running costs.

In addition to the above it is now common practice to speed control the supply and extract fans dependant on how the building is used and the number of people using a building, this is achieved by measuring the CO² % present in the extract air, with the increase of the number of people in a building and so the CO² % will increase, this is used to speed up or slow down the fans to control the number of air changers per hour in the building, this again will help reduce the energy cost as slowing the fans with an inverter will reduce the electricity used.