The Banff and Buchan College in Fraserburgh recently installed the largest AWADUKT Thermo ground-air heat exchanger system in Scotland. The installation forms part of the college’s refurbishment and extensions being carried out by Robertson Construction Northern LTD, and is expected to be completed by the end of 2011. The system’s passive cooling capability was a significant factor in it being chosen to provide a healthy and comfortable learning environment.
The REHAU system draws air from outside at a rate of 16 000 cubic metres an hour through a 42 metre by 30 metre grid of REHAU AWADUKT Thermo polypropylene pipe work, 1.5 metres below the playing fields of the college. The optimal heat transfer between the ground and air results in the air being warmed by up to nine degrees Celsius in winter. During summer the air can be cooled by as much as 14 degrees Celsius by the time it reaches the air handling unit.
This eliminates the requirement for refrigerant–based, mechanical cooling to counter the heat gain in the building, which is generated by high occupancy levels and large amounts of glazing, particularly in the atrium. This has a significant impact on the energy loading of the air handling unit.
Alan Gibb, a Senior Mechanical Engineer from KJ Tait Engineers, specified the system in response to requests from their client for an energy efficient heating and ventilation system. The system also needed to assist with securing a very good BREEAM rating, which is the Building Research Establishment’s Environmental Assessment Method.
Alan said, “On a sunny summer day when the external ambient temperature could be as high as 25 degrees Celsius, the system will deliver air to cool the atrium, which has been pre-cooled by the ground-air heat exchanger to around 10 to 11 degrees Celsius using minimal amounts of energy and with almost zero running costs. For a building which has no mechanical cooling, this will be hugely rewarding. In a learning environment where the requirement for ventilation is increasingly being recognised, the REHAU AWADUKT Thermo system is a very effective solution.”
Sparks Mechanical Services installed the system, with support from REHAU’s Glasgow sales office technical team. The pipe work grid consists of 60 metres of 1050 millimetre diameter, socketed header pipe and 1680 metres of 250 millimetre heat transfer pipe. A 70 metre run header pipe transfers air into the building.
KJ Tait monitors the temperature of the air entering the air handling unit via BMS readings. They are doing this to evaluate the performance and payback of the REHAU AWADUKT Thermo system during the first year of its operation.
For more information: http://www.rehau.co.za/