Outdoor Air Unit - The OAU is a 70 kW (20 ton) air handling unit with a DX cooling coil that is used to condition outdoor air in order to provide a source of "outdoor air" whose thermal properties can be reproduced from one test to another.
Air Handling Units - There are two AHU's, each capable of 15.5 kW (4.4 tons) of cooling, that condition a mixture of return air and outdoor air provided by the OAU for use in cooling the zones.
Variable Air Volume Boxes -There are four VAV boxes, one for each zone, which are used to modify the thermal properties and airflow rate of the air supplied by the AHU's to meet the needs of the zone.
Zone Simulators - There are four ZS's, each of which can be operated to represent the load in a zone. Each ZS contains a 5 kW (1.4 ton) electric heater, a steam spray humidifier capable of 1. 8 kg/h ( 4 lb/h) of steam, and a thermal mass coil. The TMC is used to emulate the thermal mass that exists in an actual zone due to construction materials, furniture, etc.
Condensing Loop -The CL uses NIST plant chilled water to reject heat, representing the function of a cooling tower.
Chillers -There are two chillers, one is 26.4 kW (7.5 tons) and the other is 36 kW (10.25 tons). The chillers are used to produce ice in the thermal storage tank or to provide cooling for the AHU cooling coils.
Thermal Storage - Water is frozen in the TS and can be melted to provide cooling for the AHU cooling coils.