1. Photometric Data Photometry is the science of measurement of light.
Photometric data is a set of information related to the amount of light emitted from individual fixtures.
Independent labs are used to verify and objectively report photometric data from fixture manufactures

2. Photometric Data
Photometric Data may include the following information:
Candle Power Distribution Curve
Luminaire Efficiency
Coefficient of Utilization
Spacing Criterion
Physical Dimensions
Lamp and Ballast Data
Efficacy

3. Photometric Data Candle Power Distribution Curve
Describes the direction and the intensity of light from the luminaire.
Candle power distribution curves can also help determine if the fixture may create problems with direct and reflected glare as well as problems with hot spots.

4. Photometric Data Candle Power Distribution Curve
‘Batwing’ Distribution (Good for Computers)

5. Candle Power Distribution Curve ‘Even’ Distribution
Photometric Data
Candle Power Distribution Curve
‘Even’ Distribution

6. Candle Power Distribution Curve Potential Problems:
Photometric Data
Candle Power Distribution Curve
Potential Problems:

7. Photometric Data
Indirect bat wing pattern may reduce hot spots (unacceptable bright areas) on the ceiling.
Semi Indirect with a bat wing pattern down to reduce potential of reflected glare.

8. Photometric Data
Luminaire Efficiency describes the amount of light that is emitted from the luminaire compared to the amount of light that is generated by the lamps.
All fixtures absorb some of the light from the lamps. Comparing luminaire efficiencies between fixtures allow for quick energy efficiency ratings. Ê

9. Photometric Data Coefficient of Utilization (CU)
Coefficient of Utilization (CU) is the ratio of lumens on the work surface to the lumens emitted by the luminaire.
The CU is influenced by the reflectance values of materials, size and shape of the room, and the placement of the luminaire.
The CU is used in the lumen calculation method that is used to determine the light levels for ambient lighting systems.

10. Photometric Data
High Coefficient of Utilization (CU) values means more light reached the work surface and is more efficient.

11. Photometric Data Coefficient of Utilization (CU) Table
pcc = reflectance value of the ceiling.
pw = reflectance value of walls
Typically the chart assumes a 20% reflectance value for the floor. (This is due to typically dark colors and furnishings.)
Room Ratios the larger the number the larger the room.

12. Photometric Data Coefficient of Utilization (CU) Table
Note that small rooms with light colors have a high CU.
Large rooms that are dark have a low CU.
The CU represents the percentage of lumens that reach the work surface from the fixture.

13. Photometric Data
Spacing Criteria describes the maximum acceptable distance between fixtures when they are laid out in a room. The number provided by the fixture manufacture is a ratio that is multiplied by the distance between the work plane that is to be illuminated and the bottom of the fixture.

14. Photometric Data Spacing Criteria
If the distance between the fixture and the work plane is 6 then the maximum spacing criteria would be 6X1.2 = 7.2 parallel to the fixture and 6X1=6 90 degrees to the fixture.
(Remember that these are the maximum spacing recommendations.)
7-2 MAX
6-0 MAX

15. Physical Dimensions and Finishes
Photometric Data
Physical Dimensions and Finishes

16. Photometric Data
Lamp and Ballast Data

17. Manufacture Photometric Data
Fluorescent with Wrap Around Prismatic Lens
Fluorescent with Prismatic Lens
Deep Cell Parabolic Fluorescent
Semi Indirect Fluorescent
Indirect Fluorescent
Compact Fluorescent Down Light
Incandescent Down Light
MR 16 Down Light
HID Down Light

18. Manufacture Photometric Data
HID Down Light
Pendent Fixture
Wall Washer
Placement Guide
Calculation Data