CFC and HCFC refrigerants contribute to the breakdown of the ozone layer and the greenhouse effect. CFC is an abbreviation of chlorofluorocarbon; HFC is an abbreviation of Hydrochlorofluorocarbon. They describe the molecules’ atom content.
A great part of energy consumption in a ventilation system goes to heating outside air. Great reductions in operational expense can be achieved by transferring the heat from the expelled air to the cold air that is taken in.
Heat rejection is the excess heat from a cooling system which is removed by the condenser/cooling tower. Heat rejection is the total amount of heat energy which is transferred from the cool side to the warm side, plus the work carried out by the compressor.
The heating surface can be an integrated part of the AHU, or be placed directly in the air intake duct. The heating surface is used to warm up outside air before being injected into the building.