Ventilation ducts in the ground provide low-carbon solution for serviced office development
Passing ventilation air through a Rehau AWADUKT system in the ground will provide energy-efficient preheating and precooling for a development in Northern Ireland
Low-carbon heating and cooling of ventilation air for a development of serviced business units near Belfast is provided by passing air through a network of pipes in the ground. Using this system, the temperature of ventilation air can be raised by up to 9 K in winter and reduced by up to 14 K in summer. The system was proposed by M&E consultant Bennett Robertson for Ard Business Centre in Newtownards near Belfast after extensive research of low-carbon cooling solutions. Gary Bennett explains, ‘Our client wanted an environmentally friendly, comfortable building with low energy and maintenance costs. We considered Rehau’s AWADUKT Thermo system to be an elegant and simple solution to the anticipated solar overheating for the east- and south-facing units in the development. ‘We are using the system in conjunction with conventional tempered air-handling units and night cooling. The system simply replaces conventional fresh-air inlet ductwork and louvres. Treated fresh air is supplied to the office units via displacement floor grilles, with the access floor system used both as the supply plenum and also to provide access to the floor slabs for thermal storage.’ The concept relies on a network of polypropylene pipes 1.5 m deep in the ground, where the temperature is 8 to 12 °C throughout the year. Fresh air is drawn through the pipes, and energy is exchanged between the air and the ground. A coefficient of performance of around 50 is achieved, compared with just three or four for a ground-source heat pump. The pipework has an integrated layer of silver particles to prevent microbial growth on the inside of the pipe. Bennett Robertson will monitor the performance of the system and occupant satisfaction over the first year of operation and then compare it with a twin split-system and VRF air conditioning to validate the carbon savings. This is the first use of AWADUKT in a private-sector commercial development.