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

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

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.

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

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

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

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.

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

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.

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

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.

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.

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.

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

Physical Dimensions and Finishes Photometric Data Physical Dimensions and Finishes

Photometric Data Lamp and Ballast Data

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

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