Lighting a One Car Garage

[bczygan]

This is a one car garage morphing into a metalworking shop.

I'll get more exact measurements and photos but it is 9' something by 19' something.

The structure is brick walls painted white.

Half the ceiling is rough plaster on metal lath painted white. The lath and plaster on the other half has been taken down/fell down.

The space is full of machines and cabinets and tools.

The idea was to get a bright cool white space for the least money.

So I used an online calculator to get 6-4' 2 tube T8 fixtures.

Bought the cheapest ones I could find which was the corded ones at Lowes.

Even used the $10 off $50 to save money and bought in groups.

Bought a box of the 6500K Sylvania bulbs from them too.

The ceiling is around 9' but I hung these, on the provided chains, closer to 8'.

2 rows of 3 running the long dimension.

This didn't provide enough general illumination for my old eyes.

So I just got 2 more and I am making 2 rows of 4. They end up being butted end to end with about an 18" gap in the middle of the row and some smaller space at each end.

I rehung 6 of them so far, and took them up to within about 6" of the ceiling. They are spaced off the side walls, so that the distance from row to wall is half of that from row to row.

I just went out and measured the FC in various spots, at the workbench height of about 40".

I get from 65 to 75.

The light level is such that it doesn't glare or hurt old eyes, yet I can find things on the floor, and do fine work on the bench use machines.

I might add a couple of task lights at machines, but it is almost enough to not need that.

In a small space like this, with a small number of fixtures, it is difficult to get dead even illumination levels. In fact, the level is higher at the entry door to the house, where unobstructed white door and walls, along with the light in the corner, actually give higher levels. And levels drop off where machinery, cabinets and benches block and reduce light.

The light levels are lower than my online calculator indicated, even after adding 2 additional fixtures. This could be a function of the missing ceiling, cheap fixtures, fixtures hung below the ceiling and the size, placement and color of equipment, machinery, cabinets,benches and the floor.

But the bottom line is that you need to try different layouts and quantities to get the result you want. These are good levels for me.

I'll add more exact measurements and information and photos when I get a chance.

Bill

 

[bczygan]

Some measurements:

9'5"x19'-7"

8'7 1/2" to ceiling.

Fixture rows are 29" off the side walls.

 

[Shiftless]

I am mystified about where all those lumens are going. Many GJ menbers report fantastic lighting levels when they provide 100 lumens per square foot of floor area. Assuming around 2800 lumens per bulb and you running 16 bulbs, you are running roughly 250 lumens per square foot, over two and a half times that of the general consensus of GJ members.
Hmmmmm?????

 

[bczygan]

I am mystified about where all those lumens are going. Many GJ menbers report fantastic lighting levels when they provide 100 lumens per square foot of floor area. Assuming around 2800 lumens per bulb and you running 16 bulbs, you are running roughly 250 lumens per square foot, over two and a half times that of the general consensus of GJ members.
Hmmmmm?????

Here are some photos.

I remeasured with a lighting app last night, and the measurement ranges from around 600 to 620 (plus or minus) lux in the open areas in the middle of the space. That translates to 55 to 58 FC at the 40" height I measured.

 

[cybrdyke]

Assuming around 2800 lumens per bulb.../QUOTE]

You cant get 2800 lumens out of a standard T8 lamp in real life. Standard ballast factor is .88 . 2800 x .88 = 2464. Then you have to consider fixture efficiency. That can vary from 70% to 85% for good fixtures. Now you're down to 1800 range.

Here are some photos.

I remeasured with a lighting app last night, and the measurement ranges from around 600 to 620 (plus or minus) lux in the open areas in the middle of the space. That translates to 55 to 58 FC at the 40" height I measured.

The light meter apps are only moderately accurate. They're better used for making comparisons. Just my experience.
It looks like you have very little reflectance, which would normally get taken into consideration if we were doing lighting calculations. The louvered fixtures dont allow any ceiling reflectance, and very little wall (vertical) reflectance. And all your tools, etc are blocking any floor reflectance.
IMO, that's why you're coming up short.
Good luck
CD

 

[bczygan]

Assuming around 2800 lumens per bulb.../QUOTE]

You cant get 2800 lumens out of a standard T8 lamp in real life. Standard ballast factor is .88 . 2800 x .88 = 2464. Then you have to consider fixture efficiency. That can vary from 70% to 85% for good fixtures. Now you're down to 1800 range.




The light meter apps are only moderately accurate. They're better used for making comparisons. Just my experience.
It looks like you have very little reflectance, which would normally get taken into consideration if we were doing lighting calculations. The louvered fixtures dont allow any ceiling reflectance, and very little wall (vertical) reflectance. And all your tools, etc are blocking any floor reflectance.
IMO, that's why you're coming up short.
Good luck
CD

Yes, cheap fixtures, half the ceiling a black hole and all the equipment sure contribute.

The overall ambient lighting level is adequate though. Maybe need a magnified circular fluorescent for small fine work on a bench.

And as I remove more unnecessary equipment, it will get better.

Bill

 

[bczygan]

Assuming around 2800 lumens per bulb.../QUOTE]

You cant get 2800 lumens out of a standard T8 lamp in real life. Standard ballast factor is .88 . 2800 x .88 = 2464. Then you have to consider fixture efficiency. That can vary from 70% to 85% for good fixtures. Now you're down to 1800 range.




The light meter apps are only moderately accurate. They're better used for making comparisons. Just my experience.
It looks like you have very little reflectance, which would normally get taken into consideration if we were doing lighting calculations. The louvered fixtures dont allow any ceiling reflectance, and very little wall (vertical) reflectance. And all your tools, etc are blocking any floor reflectance.
IMO, that's why you're coming up short.
Good luck
CD

I took the 1800 and using an online calculator, I end up with 8 fixtures giving 75FC at the working surface. Allowing for all the objects in the space, my 55 to 60 doesn't seem unreasonable. It's a good example of calculations versus real world results.

And it surprises me that I only need 50-60FC for general illumination.

 

[Shiftless]

More thoughts on lost lumens

So, lets use the 1800 lumens per bulb real world value.
16 bulbs times 1800 lumens each gives you about 29,000 Lumens
29,000 Lumens spread out over the total floor area, 185 square feet, gives you
156 lumens per square foot which is the same as 156 foot candles right? And you measured a bit over 55 foot candles, right?
So my conclusion is that your walls and ceiling and dark colored pieces of equipment are absorbing something like two thirds of your light.

Am I making some errors here? Please set me straight if you know more about this than I do.

 

[Platonic Solid]

bczygan 9x19x9

Don't think of it as adding light fixtures to a room, think of the room as one large light fixture. Obviously, your "light fixture" (room) is in dire need of repair. Fix the ceiling - paint it ceiling white and paint the walls satin white (at least the top 4 feet anyway) as this becomes your fixture (room) reflector.

Get Qty. 12 of Cooper Metalux SNF132RC $19.98

Suggested Lamp: Qty. 12 Sylvania 22026 (5000K) or 21767 (4000K)
5000K Fluorescent T8 Fo32/850/Xp/Eco3 available at globalindustrial.com for $2.93 each.
or
4000K Fluorescent T8 Fo32/841/Xp/Eco3 available at globalindustrial.com for $3.37 each.

Install like this:

 

[bczygan]

More thoughts on lost lumens

So, lets use the 1800 lumens per bulb real world value.
16 bulbs times 1800 lumens each gives you about 29,000 Lumens
29,000 Lumens spread out over the total floor area, 185 square feet, gives you
156 lumens per square foot which is the same as 156 foot candles right? And you measured a bit over 55 foot candles, right?
So my conclusion is that your walls and ceiling and dark colored pieces of equipment are absorbing something like two thirds of your light.

Am I making some errors here? Please set me straight if you know more about this than I do.

Lumens are a metric measurement of output.

Foot candles are an English measurement of illuminance.

They don't correlate equally.

Perhaps others can explain.

Bill

Bill

 

[bczygan]

Re: bczygan 9x19x9

Don't think of it as adding light fixtures to a room, think of the room as one large light fixture. Obviously, your "light fixture" (room) is in dire need of repair. Fix the ceiling - paint it ceiling white and paint the walls satin white (at least the top 4 feet anyway) as this becomes your fixture (room) reflector.

Get Qty. 12 of Cooper Metalux SNF132RC $19.98

Suggested Lamp: Qty. 12 Sylvania 22026 (5000K) or 21767 (4000K)
5000K Fluorescent T8 Fo32/850/Xp/Eco3 available at globalindustrial.com for $2.93 each.
or
4000K Fluorescent T8 Fo32/841/Xp/Eco3 available at globalindustrial.com for $3.37 each.

Install like this:

Some questions and comments.

First, what software (Online or off) are you using for your charts and layouts?

Second, I already have 8 fixtures. The ceiling will be redone. I'm going to tear off the other half and run a gas line and some electrical up there and insulate, then either drywall or use white painted steel panels. But for now, I'm getting an adequate level of light for general illumination. My layout is like yours, minus the 4 in the middle. If I added those, I have no doubt that the levels would come up, perhaps to the levels you show.

I have corded because they are easy to move around and reposition. Also, the fixtures and lamps were bought at Lowes with $10 off $50, so fixtures ended up costing about $15 each. I'm not so concerned about the ceiling reflecting, so having reflectors on the fixtures is OK. And I love the 6500K lamps I'm using.

I do appreciate the cleaner look of the ceiling mounted and hard wired fixtures though. Even lenses would make things look more finished. Even recessed.

I might pick up 4 more to try your layout. I can always use them elsewhere if they are too much. That's the fun of a small garage. Trying different things doesn't cost too much.

Bill