Smart mart
I Sainsbury's Horsham store in Sussex, Britain, goes green by adopting secondary refrigeration for storing both chilled and frozen foods. Ammonia is used as the main refrigerant while the secondary cooling agent is a combination of glycol and silicon oil (Technology Partnership Initiative, issue 7).
Each of the nine compressors contain 140 kg of ammonia, while the secondary system uses 3,960 kg of propylene glycol. Serving 41 chilled use sections, the system can recover heat. The likelihood of leaks has been minimised by operating the unit at low pressure and maintaining a constant flow in the secondary circuits.