October 12, 2012
Technological innovation and service capabilities were some of the main criteria used by the judges – David Frise, head of sustainability at the B&ES; Mike Smith, engineering director at BSRIA; CIBSE technical adviser Gay Lawrence Race and Mike Duggan technical manager at FETA (Federation of Environmental Trade Associations) – when considering nominations and deciding on the winners.
In providing an effective alternative to centralised AHU/ductwork systems, Demand Controlled Ventilation also reduces capital costs and makes it easy and cost-effective to improve ventilation and energy efficiency in existing buildings.
SAV Systems specialise in providing low carbon, energy efficient solutions for the building industry. The company provides support to building services engineers, architects and consultants, by offering innovative solutions such as AirMaster Demand Controlled Ventilation, LoadTracker CHP, FlatStation Heat Interface Units, HVAC Commissioning Modules and Automatic Energy Monitoring and Targeting.
At the end of 2011, the Surrey based company opened its Low Carbon Technology Centre which integrates SAV’s eco friendly solutions within the heating and ventilation of the building.
Entrant: SAV Systems
Product(s): AirMaster Decentralised, Heat Recovery Air Handling Units
SAV Systems’ AirMaster direct, zone-specific heat recovery air handling units have been specifically designed to deliver localised Demand Controlled Ventilation (DCV) with low noise levels – controlling Indoor Air Quality (IAQ) quietly and efficiently within each individual zone.
AirMaster units are mounted within the space being ventilated, at ceiling height or or at floor level, and use direct connections to the outside through an external wall or roof. They are available in capacities from 100 m3/h to 1310 m3/h.
High efficiency counterflow heat exchangers ensure heat recovery of up to 91% (at 80% RH), while electronic commutation (EC) motor technology enables low Specific Fan Power and reduced energy consumption.
When combined with CO2 sensors, AirMaster Heat Recovery Systems deliver true Demand Controlled Ventilation (DCV) at local level, using Class M5 filtration on both supply and extract air flows to maintain IAQ and keep heat exchanger efficiency high.
Wall units can be mounted close to the ceiling or partly recessed in the ceiling void. In both cases they provide an even distribution of air across the ceiling, exploiting the so-called Coanda effect, so that supply air falls gently into the space towards the back of the room. Floor mounted Air Handling Units can be installed against the wall or used as partitions. They can be configured to provide ventilation either by mixing or displacement.
SAV Systems entered into a strategic partnership with AirMaster AS early in 2012, which led to AirMaster decentralised air handling units being introduced to the UK market. This move was specifically to offer an energy-efficient alternative to traditional centralised air handling systems. AirMaster designs have been tried and tested in a wide range of applications in Scandinavia.
A ventilation system using Demand Controlled Ventilation needs to be highly responsive to changes in IAQ, as measured by parameters such as CO2 levels, occupancy and relative humidity.
In contrast, centralised air handling systems respond to such changes by using dampers within the distribution system. This arrangement is prone to commissioning errors and imbalance in delivery. However, the AirMaster decentralised AHU is within the space to be controlled and can react promptly by modulating or on/off operation. Local manual control can also be provided.
Nor does this arrangement sacrifice the benefits of centralised control, as up to 16 AirMaster units can be slaved to a single controller, or take their instructions from a Building Management System. However, they would still retain their ability to operate independently.
As maintaining good Indoor Air Quality is the primary reason for using Demand Controlled Ventilation, it is vital to keep high levels of filtration for both supply and extract air. Ventilation standard EN 13779 recommends filters to Class M5-F9 to remove outdoor pollutants from supply air. Class M5 is also the minimum requirement for pr
eventing a build-up of grease on the heat exchanger surfaces. On the other hand, lower class filters can lead to a build up of deposits on the heat exchanger with attendant loss in performance. They may also allow a build-up of organic material in the condensate tray, with the potential for fungal growth.
AirMaster units are supplied with Class M5 filters as standard, using a pleated design to increase surface area by around 40% relative to flat designs, and thus keep pressure losses to a minimum.
When compared to centralised systems, SAV’s AirMaster can deliver significant energy savings. For example, AirMaster helps to avoid the wasted energy by over-ventilation which is associated with traditional ductwork systems designed for maximum throughput to the whole of the building. Furthermore, AirMaster units do not have to expend energy either in overcoming the air resistance of a centralised ductwork system, or by heat loss from the distribution ducting between the centralised AHU and the outlets.
For maximum recovery of heat from extract air, AirMaster units are fitted with counterflow heat exchangers tested to EN 308. They have a rated efficiency of 84% with dry air and 91% at 80% relative humidity.
SAV Systems’ AirMaster AHUs are fitted with variable speed fans using EC motors as standard. The unit’s motor control system ensures one of the lowest energy consumption rates on the market. AirMaster units have a Specific Fan Power in the range of 0.7 – 1.2 w/l/sec, which takes account of both fans, all electronic circuitry and actuated dampers.
Extensive research has shown that the aluminium heat exchangers used by AirMaster provide much longer service than the those made of plastic.
AirMaster can also be used to provide night-time cooling of the building fabric, so as to make temperature reduction easier during the subsequent day. Where required, units can also be fitted back-to-back with an auxiliary cooling module, designed to be dimensionally compatible with the AHU and to be fully integrated with the control panel.
Noise is one of the issues that most concerns specifiers when bringing a ventilation system close to the occupied space. AirMaster units have a noise level at full throughput of only 35 dB(A) at 1 metre (equivalent to a normal library), and and an even lower 30 dB(A) at 1 metre at 80% capacity.
Decentralised ventilation systems are not vulnerable to intrusive noise entering further upstream through the ductwork, as would be the case for a centralised system. This means that the 35 dB(A) at 1 metre can be regarded as the true maximum noise emission.
By eliminating the need for complex and extensive centralised ductwork systems, as well as by avoiding penetrations through fire compartments, SAV’s AirMaster Heat Recovery systems help to reduce capital and installation costs.
AirMaster makes it easy to extend ventilation to other rooms at a later stage by simply introducing additional air handling units. By contrast, extending a traditional ductwork system is disruptive and expensive, and may also require upgrading of the central plant.
Decentralisation improves the viability of retrofitting an effective demand controlled ventilation system to an existing building. This will become increasingly important as many older buildings have their insulation and air tightness upgraded to reduce energy consumption.
Ventilation systems using central air handling plant to distribute and extract air through a ductwork system have been the norm in commercial and industrial applications for many years. That being said, the maintenance of Indoor Air Quality in buildings, especially in schools and universities, has depended as much on the general lack of air tightness of the building (meaning draughts) as it has on the ventilation system.
As building tightness improves, there is growing concern about the potential decline of Indoor Air Quality (IAQ). This gives rise to the need to ventilate in the most energy efficient way possible, with growing acceptance that Demand Controlled Ventilation (DCV) will be an essential part of the ventilation mix.
This view has been reflected in recent consultations in the run-up to the publication of the Building Regulations 2013. There is a strong likelihood that the future SBEM notional building will incorporate Demand Controlled Ventilation, therefore any proposed building design in the future which does not incorporate DCV can be expected to score relatively poorly.
In SAV Systems’ view, these developments create the need for a re-think about how ventilation is delivered, particularly in relation to maintaining IAQ in the most energy efficient manner.
This was the primary driver for SAV to team up with AirMaster AS, a Danish ventilation specialist. AirMaster’s innovative solutions have been developed to comply with Northern European standards and best practice, which currently are considerably more rigorous than those used in the UK. By building on the 20+ years experience gained by AirMaster in this field, SAV are well-equipped to support HVAC specifiers and building operators on new-build and refurbishment projects to help them achieve the highest standards of low carbon, decentralised, demand controlled ventilation.