A series of tests was conducted to establish the sensitivity of the Air Diffusion Performance Index (ADPI) to various parameters. Tests were conducted in a 12 ft (3.7 m) x 15 ft (4.6 m)room with a single 4 ft (1.2 m) slot diffuser located near a simulated perimeter windowed wall. Outside temperature, slot geometry, outlet velocities, cfm’s, and room height were varied. Because of the large number of parameters, a fractional factorial experiment was de­signed with two extra tests for the determination of test repeatability. It was found that a single 4 ft (1.2 m) linear diffuser could provide ADPI indices of 70% or better within the test parameter values.