Actionair FCUs as part of controllable low-energy air conditioning
As part of the low-energy refurbishment of two buildings near Bath for Helphire, air-conditioning is provided by Actionair fan-coil units with electronically commutated motors and digital control.
Actionair fan-coil units with DC electronically commutated motors have been used in the major refurbishment of two former MoD buildings near Bath to provide a new headquarters for Helphire Group, which specialises in replacement transport and other insurance-related services for motorists. The use of these motors can reduce power consumption by up to 40%, suiting them to low-energy environmental control. The heat gain from the fan motors is reduced by two-thirds. Around a thousand staff are accommodated in open-plan offices at high density, 6 m2 per person, so air conditioning was essential. The high energy performance of these FCUs helped designers at Jacobs of Cardiff to develop a low-energy solution for the project. Both buildings were stripped out to leave only the original walls and floor, and high levels of insulation were installed. Heating and cooling are provided by over 200 Actionair EHW 230 fan-coil units located horizontally in the ceiling voids. These units are designed to operate at constant volume against pressures from 10 to 60 Pa. The volume can be set at the factory using a potentiometer which transmits a constant voltage to the fan controller. Commissioning time is greatly reduced as the only requirement is to balance airflow through each branch. A 0 to 10 V DC output to a DDC controller offers further energy-saving benefits Until the room load is met, the FCU runs at the selected speed and duty and related noise level. The unit then throttles back by automatically reducing fan speed in response to a ‘ramp’ signal from the controller. If the room temperature varies too much from the setpoint, the controller will put the fan into auto-boost mode for quick recovery.