The throw room in CMEST is a state-of-the-art, specially designed room for measuring the air flow characteristics of grills, registers, diffusers, and other types of room ventilation devices. The room is 30 ft long by 22 ft wide. It has a 3-ft raised floor for testing floor diffusers and under-floor air distribution systems. The height of the room ceiling can be varied from 8 ft to 13 ft. The throw room can be used to conduct full-scale mockup tests of the airflow and sound characteristics of ceiling air terminals and above-the-ceiling air terminal devices.

The room contains a computer-controlled, four-axis (three translational axes and one rotational axis) traversing system. This system is used in conjunction with a three-wire, hot-wire anemometer and other related transducers to measure the flow-velocity characteristics of grills, registers, diffusers, or other ventilation devices that may be in the room. The four-axis traversing system can be programmed to make measurements at specified points within the room or to set the room up in a three-dimensional grid pattern and then make measurements by sequentially scanning the grid points.