question about lumens?

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steveng said:
what is the formula for figuring the lumens(lighting fixtures) in a school classroom?

room size is 30' x 25'
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I would contact one of your lighting rep's. Most manufactures have lighting calc programs to determine the lumen level for a specific application. There are several questions you would need to answer such as, what kind of classroom, ceiling height, wall color (reflectance) work area height etc. All types of classrooms do not require the same level of lighting.

Grant
 
The IES has published these lumen tables for many tasks for probably 50 years or more. As has been pointed out, it depends on the type of classroom. The lighting level for classrooms can vary between 40 and 100 footcandles. A little less in a computer lab, and little more in a science room, as a couple for instances.

http://www.iesna.org/
 
Lithonia also has a very cool software package, Visual, that has all of the IESNA recommendations listed, and will even lay out the particular fixtures for you, if you give it the recommended foot-candle level, the room dimensions, and the desired fixture.
 
thanks guys

thanks guys

bcorbin said:
Lithonia also has a very cool software package, Visual, that has all of the IESNA recommendations listed, and will even lay out the particular fixtures for you, if you give it the recommended foot-candle level, the room dimensions, and the desired fixture.
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thanks guys, you have helped a bunch,
i decided to increase the output lumens approx 50 % in this classroom,
i used about 20 per square foot. used 12 -4 lamp t8 fixtures.
 
bcorbin said:
Lithonia also has a very cool software package, Visual, that has all of the IESNA recommendations listed, and will even lay out the particular fixtures for you, if you give it the recommended foot-candle level, the room dimensions, and the desired fixture.
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Visual is a very handy app...

Download the basic version. It's free and will do much of what you're after. You will need to know what type fixture to use, but your local rep can help. Even if your local rep isn't a lithonia rep, you can get close enough using an equal. Here's a link:

http://www.visuallightingsoftware.com/

I use it all the time to create scenarios, print to a pdf then allow clients to make a decision based costs, light levels, etc.

Basics (very):

Lumens is basically lamp output and doesn't translate easily to a given light level. The standard is footcandle i.e. 50 fc @ the student's desk. It takes x number of lamps putting out x lumens in the right direction using x number of fixtures to provide that 50fc.

I would never discuss lighting in terms of lumens. In the back of my mind I know I need lamps putting lumens out to arrive at a desired light level i.e. footcandles.

There's a lot to consider w/ lighting classrooms; daylight harvesting, controls, etc. I've done a lot of schools and around these here parts; schools are very demanding lighting jobs but once you know the trick, they're all pretty much the same.

Anywho... the lighting bible (IESNA Lighting Handbook) ain't cheap, but what tool is? If you do even a bit of lighting it's (IMO) a required tool.
 
when we do standard class rooms we put 60ft candles on the floor where the students set and 50ft candles by where instructor stands on the floor..that way it is bright enough to read and take notes and reduces glare so the students can see the white board in front of class room..
 
Also, for anyone doing any amount of lighting work, buy a light meter and sample existing lighted environments as well as those you design once built. Knowing what 50fc "feels" like will go a long way in making lighting decisions.
 
If this is an institution that receives State or Federal funding, you may be required to comply with various Energy standards (LEED). Before you write a P.O., you might want to check with your Facilities Engineering Department.
 
barclayd said:
If this is an institution that receives State or Federal funding, you may be required to comply with various Energy standards (LEED). Before you write a P.O., you might want to check with your Facilities Engineering Department.
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LEED? Perhaps if they (owner) desire to, but more likely ASHRAE 90.1; a mandated standard.
 
50 Foot Candles is good design criteria. You would also need to understand wall reflectance, mounting height and working plane. Read lithonia's website. The site has design considerations as well as definitions with examples.
 
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