These air streams are distributed all through the area served by the air handling unit in separate and parallel ducts. Each zone has a terminal mixing field managed by zone thermostat to adjust the availability air temperature by combine the supply cold and warm air.
This temperature is beneficial to keep away from too much heating above occupants’ heads. The dual duct all-air system is a terminal-managed modification of the multi-zone idea. A central air handling unit provides two conditioned air streams such as a cold deck and a hot deck, as shown in Figure 7.
This could be observed in larger residences, where two (or more) single zone methods could also be used to supply thermal zoning. In low-rise residences, every house unit may be conditioned by a separate single zone system. Many sizeable single story buildings such as supermarkets, discount stores, can be effectively conditioned by a series of single zone techniques. Large workplace buildings are generally conditioned by a collection of separate single zone systems. However, the number of a system has some constraints that must be determined.
This kind of system will minimize the disadvantages of earlier methods and turn out to be more versatile by using terminal management. Although few buildings could be a single thermal zone, a single zone can be present in a number of applications.
One family residential buildings may be handled as single zone systems, while other types of residential buildings can embody different thermal energy based on the occupation and constructing structure. Movements of occupants affect the thermal load of the building, which results in dividing the building into a number of single zones to provide the required environmental situation.