Fresh air, with the windows wide shut!

The engineering challenge

Fresh air, with the windows wide shut!When it’s unacceptable to open the windows, how do you meet the requirements of Part F of the Building Regulations? At the same time, how do you address the specific requirements for low noise in areas such as classrooms, libraries and offices?

The engineering solution

The solution is to install localised, zone-specific
mechanical ventilation with heat recovery. Not only does it deliver fresh air with low noise operation but also dampens the ingress of external noise.


Irresistible force – Immovable object

Part L (Conservation of Fuel & Power) of the Building Regulations includes the requirement to improve the ‘air tightness’ of buildings, thus reducing reliance on the permeability of the building for ventilation.


Part F (Ventilation) of the Building Regulations is designed to ensure that acceptable Indoor Air Quality (IAQ) is maintained in buildings.


Compliance with the requirements of both creates a conflict. This is apparent with natural ventilation options such as opening windows or using the stack effect, where the following can be expected:

  • Uncontrolled energy losses through lack of heat recovery.
  • Noise and pollution ingress from outside.
  • Uncontrolled CO2 levels.
  • Draughts and temperature fluctuations.
  • Windows being opened in response to rising temperatures, rather than IAQ.

Traditional, centralised AHU ventilation also has its drawbacks:

  • Extensive and costly ductwork, which can be hard to retrofit.
  • High air resistance, due to long ductwork runs.
  • Sluggish response to local IAQ.
  • Heat loss before extract air reaches the heat recovery stage of the AHU.
  • Difficult to extend or reconfigure, in the event of changes to the building.

How can all these be avoided?

Direct, zone-specific air handling units with Demand Controlled Ventilation and heat recovery

airmaster newsletter

2 x AML 500 AirMaster units in Reception classroom, partly recessed in ceiling void, with demand control of CO2 level.

SAV’s AirMaster is a direct, zone-specific air handling unit that delivers excellent control of IAQ, combined with energy efficiency and low noise. It comes into its own in any situation where opening windows is not admissible.

AirMaster units are installed in the space that is being ventilated, with short connections to the outside through a wall or roof. They respond directly to local ventilation requirements.