The Revolution in Classroom Ventilation

AirMaster direct, zone-specific air handling units with demand control, heat recovery and optimal energy efficiency.

SAV’s AirMaster is a direct, zone-specific air handling unit that is ideal for use in classrooms, lecture theatres and other educational spaces.

AirMaster units are installed in the space that is being ventilated, with short connections to the outside through a wall or roof, so that they respond directly to local ventilation requirements. Their key features include:

  • Effective control of Indoor Air Quality.
  • Demand Controlled Ventilation, perfect for spaces with variable occupancy
  • Low noise levels – 35db(A) at 1m (equivalent to a normal library).
  • AirMaster heat exchangers conform to EN308 and recover at least 84% (on dry bulb) of the heat energy contained in the outgoing air.
  • EC motor technology to maximise energy efficiency (specific fan power between 0.7 and 1.2 W/l/sec at maximum airflow)
  • High quality air filtration levels as standard: filter classification conforms to EN 13779 – the European Norm.

By avoiding the constraints imposed by inflexible, centrally ducted AHU systems, AirMaster helps further by:

  • Through-the-wall or through-the-roof installation
  • Discreet high wall or floor mounting
  • No extensive ductwork installation
  • No requirement for suspended ceilings
  • Innovative design maintains separation of inlet and exhaust air
  • System can be expanded one room at a time
  • Easy retrofit to existing buildings
  • Reducing flow to any room or area left unoccupied

AirMaster AHUs have been delivering effective, energy-efficient ventilation to classrooms in Northern Europe for many years, complying with the rigorous standards that are becoming the norm in the UK. SAV Systems has therefore teamed up with leading Danish ventilation specialist AirMaster AS to bring these innovative units to the UK education sector.

As building tightness improves and there is less natural air leakage, there is growing concern about indoor air quality (IAQ), and the need to ventilate in the most energy efficient way possible. There is also growing acceptance that Demand Controlled Ventilation is the most efficient way to address this issue.

Achieving good Indoor Air Quality with a responsive, efficient and long-life system imposes a number of challenges:

CHALLENGE 1: Inability to respond to changing ventilation requirements

Natural ventilation as used in classrooms is often unable to respond to changing ventilation requirements caused by variable occupancy, other than by manually opening windows.

Windows are likely to be opened in response to a rise in temperature, rather than to changes in air quality, (such as CO2 levels). Opening windows wastes heat during the colder months.


As AirMaster units are mounted within the space they ventilate, they are ideally positioned to respond quickly to any changes in key IAQ parameters as detected by CO2 or relative humidity sensors. As a result, they are highly responsive to variable occupancy and other factors that may influence Indoor Air Quality.

CO2 sensors can be wall-mounted or fitted integrally to the air handling units, providing a signal which is linked to fan speed. As CO2 level rises with occupancy, fan speed accelerates accordingly and thus maintains excellent Indoor Air Quality.

CHALLENGE 2: Local ventilation systems become less responsive over time


AirMaster units are fitted with Class M5 filters as standard (as recommended in EN 13779) on both supply and extract airflows. As well as maintaining Indoor Air Quality, these filters protect the heat exchanger from fouling, ensuring that heat exchange efficiency is maintained. Where external air quality is expected to be poor, AirMaster units can be supplied with filters up to Class F7.

CHALLENGE 3: Traditional designs based on simultaneous usage in all rooms results in wasted energy

Furthermore, extending or re-configuring centralised ventilation systems is complex, expensive and disruptive to the building’s occupants.


AirMaster air handling units can be located just where they are needed and the system can easily be extended at a later stage by the addition of further units. On most models, ‘plug and play’ cooling units can be provided initially or retrospectively.


CHALLENGE 4: Local systems can be noisy

AirMaster mechanical ventilation with heat recovery (MVHR)units have been specifically engineered with low noise levels
so that occupants are not disturbed. Typical noise levels at just
1m distance are only 35dB(A) at 100% power and 30dB(A) at 80% power. This complies with the recommended indoor ambient noise levels for classrooms and general teaching areas.

CHALLENGE 5: Extensions to existing ventilation systems can be expensive to provide.


AirMaster AHUs can easily be installed during refurbishment programmes, one room at a time. There is no requirement for additional ductwork to a centralised air handling unit. Given a flat surfaced ceiling, AirMaster MVHR units can supply air effectively using the Coanda effect, without further need for in-room distribution ducting.

The effect of CO2 levels on student performance

Studies carried out by the University of Exeter have shown that CO2 levels exceeding 1,500 ppm can lead to a 5% reduction in Power of Attention measures. CO2 levels in naturally ventilated classrooms are often above 1,000 ppm and frequently exceed 2,000 ppm.

Reducing CO2 levels by adequate ventilation improves the performance of students and reduces the risk of accidents in practical subjects. Studies in Denmark have shown that an increase in fresh air rates from 5 l/s to 10 l/s per person results in a 29% improvement in cognitive performance.

Field trials by the International Centre for Indoor Environment and Energy, found that deterioration in Indoo Air Quality – and increased CO2 concentrations in particular – have a more profoundly negative affect on cognitive performance than rising indoor temperature.

Effects of CO2 levels

  • 400-1000 ppm The condition for optimal learning
  • 1200-2000 ppm Fatigue, impairment of concentration
  • 2000-5000 ppm Fatigue, headaches, increasing loss of concentration
  • >5000 ppm Serious lack of oxygen, faintness, tasks seriously affected

Air Handling Units – ideal for all spaces

AirMaster units are versatile and are available in a range of sizes, from ceiling mounted units for single offices to floor mounted units for larger spaces.

Some examples of school projects where AirMaster ventilation has made a difference:

  • Applications is SEN schools, where noise reduction to 30dB(A) at 1m is especially valued.
  • Inclusion in classrooms facing out on to busy roads. Strong noise attenuation when passing through AirMaster air handling units effectively
  • neutralises external noise.
  • Use as background ventilation alongside natural provision by windows.
  • Multizone applications, with simultaneous air supply to classrooms and extract from toilet areas.
  • Ventilation of offices for senior staff using the ceiling mounted AM 100 heat recovery air handling unit.
  • Ventilation of atrium areas using the larger floor mounted AM 1200 unit, with ducted extraction at high level.
  • Ventilation of classroom areas using the flagship AM 800 model, rated to serve up to 32 people on boost at 8 l/sec/person.

SAV Systems provides a full design support service to ensure that each AirMaster unit provides maximum benefit in terms of performance, ease of installation and energy saving.