Tilt Correction factors

Luminaires containing metal halide lamps often require a correction factor to be applied when the luminaire is tilted. The specific correction factors are contained in the IES format photometric file and are the responsibility of the luminaire manufacturer. Luminaires whose photometric files contain tilt information will have tilt correction factors applied whenever the luminaire is tilted. Specifically, when the luminaire is located, re-aimed or edited, the tilt information is extracted from the photometric file and the tilt correction is calculated. AGi32 looks at the luminaire's tilt angle and compares it to tilt angles and respective tilt factors within the photometric file. If the file does not contain the tilt angle, AGi32 interpolates linearly between the supplied angles to obtain the tilt correction factor. The tilt correction factor is then applied to the calculated illuminance from the tilted luminaire. This process is repeated for each luminaire in the job file employing a tilt.

The following metal halide tilt correction factors are provided courtesy of Venture Lighting International, Inc.

Tilt Angle from Nadir (in degrees)	Lamp = 1000/U	Lamp = 1500/HBU
0	1.00	1.00
15	0.97	0.97
30	0.94	0.94
45	0.90	0.90
60	0.88	0.88
75	0.87	0.87
90 (horizontal)	0.98	0.98

The tilt factors and relative angles are contained in the IES format file. For more specifics, please refer to IES document LM-63 or additional data provided here.

Per IES Standard file format, tilt correction is applied only to all tilted luminaires, and does not account for other aiming angles, such as Roll and Spin. In addition, the tilt correction factor is applied to tilted luminaires regardless of lamp-to-luminaire geometry. Refer to IES document LM-63 for detailed technical information.

The Luminaire Location Summary may contain (if selected) the tilt correction factor (TCF) for each luminaire placed on the drawing. Luminaires whose photometric report does not include tilt data will have a TCF equal to 1.0. Luminaire arrangements and luminaire groups will have an average TCF calculated. In addition, an average TCF will be calculated for all luminaires.