Air conditioning provided by 'commission-less' Matrix 2 underfloor 4 pipe fan coil units, manufactured by Ability Projects Ltd, is an important component of the building services for the new Cabot House, Bristol HQ of the Environment Agency.
Already 'flagged up' as the greenest complex of its type in the UK, the building has received the highest ever design and procurement stage BREEAM rating of 85.06% and relocating to energy efficient Cabot House should save the Agency £180,000 per year in operating and energy costs.
A total of 124 Matrix 2 underfloor fan coil units, fed with chilled water from a ground source heat pump (boosted by a chiller) and gas fired boilers, receive tempered fresh air at 100C and provide 200kW of free cooling. All fan coil units provide top access, have self balancing EC/DC motors, are pre fitted with BACNET controls and self balancing PICC valves and meet NR35 requirements environment at 30 Pascals resistance. Nominal unit cooling and heating capacities are just under 4.5kW. All units are also delivered to site with water flow rates, air volume and MAC addresses down loaded into their terminal controller strategy during manufacture - facilities that are unique to Matrix 2 models.
When installed, Matrix 2 units sense their surroundings and adjust automatically to provide and maintain the factory preset air volume and water flow design values. Furthermore, after a fit out, any value within the control strategy can be altered and transmitted to either a single fan coil, a group of fan coils, or the entire building system can be re-set in seconds through the software alone.
Once installed, each fan coil establishes the correct air volume as a total and along each individual duct, irrespective of the external static pressure of the ductwork system. Subtle variations between ductwork runs do not matter because the fans self compensate.
When installed, the fan coil control valve modulates between 0% (closed) and 100%, enabling the water flow rate to be adjusted through the software or the BMS, without the need for access to the fan coil itself. Flow rates are set with an accuracy of +/-2% on the maximum flow rate, and often even closer. The commissioning process therefore, becomes one of mere 'checking' rather than 'setting'.
As well as banishing volume control dampers, Matrix 2 also removes the need for flow regulating devices, double regulating valves or similar, in the hydraulic system. It also helps limit energy consumption, enabling air volumes to be gradually reduced or increased in parallel with thermal load and reacts to an 'unoccupied/occupied room' situation by relaxing cooling and heating set points.