Basic Documentation

Environment Adjustment Factor
14 in. dia. 11.5 6.6 3.0 1.0 0.3 0 0 0
16 in. dia. 10.5 5.8 2.5 0.8 0.2 0 0 0
18 in. dia. 9.6 5.1 2.1 0.7 0.2 0 0 0
20 in. dia 8.8 4.5 1.8 0.6 0.1 0 0 0
6 in. sq. 17.2 11.8 6.8 3.1 0.3 0.1 0 0
8 in. sq. 14.9 9.7 5.1 2.1 0.2 0 0 0
10 in. sq. 13.2 8.1 3.9 1.5 0.1 0 0 0
12 in. sq. 11.7 6.9 3.1 1.1 0 0 0 0
14 in. sq. 10.6 5.9 2.5 0.8 0 0 0 0
16 in. sq. 9.6 5.1 2.1 0.7 0 0 0 0
18 in. sq. 8.7 4.4 1.7 0.5 0 0 0 0
20 in. sq. 8.0 3.9 1.4 0.4 0 0 0 0
Environment Adjustment Factor
The Air Conditioning & Refrigeration Institute (ARI) has established ARI Standard 880-89 (Air
Terminals) for testing, rating and certifying HVAC air terminals and outlets. The device noise
rating is part of the data that the tests provide.
ARI Standard 885-90 (Procedure for Estimating Occupied Space Sound Levels in the
Application of Air Terminals and Outlets) states that an Environmental Adjustment Factor
should be subtracted from the sound power rating of terminals and outlets if the sound power
test data has been measured under free field (open space) conditions rather than
reverberant (room like) conditions.
When utilizing a manufacturer’s sound rating data, verify whether the data has been obtained
under a reverberant or free field test setup. If the data has been obtained under a free field
test condition, then subtract the Environmental Adjustment Factor from the free field sound
rating data:
63 125 250 500 1,000 2,000 4,000 8,000
Hz Hz Hz Hz Hz Hz Hz Hz
-7 dB -3 dB -2 dB -1 dB -1 dB -1 dB -1 dB -1 dB
Environmental adjustment factors for noise rating data obtained under Free Field test
conditions.
Space Effect
The last factor affecting attenuation of the sound power level to an acceptable room sound
pressure level is the ability of the room to absorb and attenuate the sound power.
Siemens Building Technologies, Inc. 63