Mike Dolt Enterprises
Mike Dolt Enterprises
User: nizak, Location: PHX, arizona
Asked on: Friday, March 25, 2011 at 5:03 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:17 am EDT
Question: I have a 14'x27' room with 14' high ceilings, white painted walls and an unpainted concrete floor.This is commercial space and will be used as a 24/7 self serve wash area for dogs.Owner tells me that he want's to make sure that it is "bright" yet really knows nothing about foot candlesor lighting in general. I would like to use 4'4 lamp t-8 surface fixtures w/F32T8/SP50 lamps. Any suggestions as to how many fixtures I will need. I realize I'm not giving much info as far as how bright it will be. What are the standard specs for let's say retail commercial space?Thanks
Calculating Lighting Requirements
To determine the number of fixtures needed, we need to consider the following factors: Desired Illuminance Level
The Illuminating Engineering Society (IES) recommends an illuminance level of 50 foot-candles (fc) for retail commercial spaces.
Fixture Efficacy
The F32T8/SP50 lamps have an efficacy of 50 lumens per watt (lm/W).
Fixture Efficiency
Assuming a fixture efficiency of 85%, the output of each fixture is 50 lm/W x 32 watts x 0.85 = 1360 lm.
Ceiling Height
The high ceilings in this space will reduce the illuminance level, as the light must travel a greater distance to reach the floor.
Room Dimensions
The room is 14' x 27' = 378 sq. ft.
Foot-Candle FormulaIlluminance = (Number of Fixtures x Fixture Output) / Room Area
Solving for Number of FixturesNumber of Fixtures = (Illuminance x Room Area) / Fixture Output
Estimating Illumination Needs
Based on an illuminance level of 50 fc and the calculated fixture output, we can estimate the number of fixtures needed:Number of Fixtures = (50 fc x 378 sq. ft.) / 1360 lm= 8.87 fixtures
Recommendation
To ensure adequate brightness, it is recommended to use
9 4'4 lamp T8 surface fixtures with F32T8/SP50 lamps. This will provide approximately 45 fc throughout the space, which is close to the desired level of 50 fc.
Additional Considerations: The fixtures should be evenly distributed throughout the space to provide uniform illumination. Consider using energy-saving motion sensors to turn off the lights when the space is unoccupied. The lighting should be designed to minimize glare and shadows, which can be especially important for a space where people will be handling animals. Flag for review