Lighting Layout Recommendations

[TurboEuro88]

(Crosspost from a comment made in my garage thread)

Been playing around with lighting layouts over on visual-3d.com to get a sense of how many fixtures I should order. Based on wanting around 100FC @ a 3ft workplane, it's been telling me I need 12-13 fixtures but the layout it wants to use doesn't really work with how I'd like to configure the lights. Yes, its a 2-car garage but if I am actually working on or detailing either car only 1 is going to be in there. It would make most sense then that I'd have the lights in a U-shape to make sure I had a light fixture above/behind me. The problem I run into there is that it drops me to ~80FC @ 3ft workplane. Thoughts? Keep in mind the layout of the garage itself, which will have a workbench at the far end, but I'll have under cabinet lighting giving the workbench its own work lighting. It should also be mentioned that the light fixtures I'll be ordering have a higher lumen output than what I could find on visual-3d.com (5200lm vs 4600 on visual-3d), so I imagine that will help mitigate things. I am also basing all this on the garage floor being epoxy coated in a light gray which should help in reflectance as well.

Base Layout @100FC:


Revised 2-row Layout:


Ideal U-shaped Layout:

 

[cybrdyke]

How did you come to choose 20/50/60 for room reflectances?
CD

 

[pbon]

I like the U or the 3 row. Few have said they have too much light. And you can use dimmers and switches to reduce or turn off lighting. I have 17 5200L 5000k lights on 4 dimmer switches in a 23x29 plus 3 more in a 6x15 bump out on one side and think it’s just about the right amount of lighting.

 

[TurboEuro88]

How did you come to choose 20/50/60 for room reflectances?
CD

No idea. Either it was a default entry or something I typed in unknowingly. Feel free to advise of more appropriate numbers.

I like the U or the 3 row. Few have said they have too much light. And you can use dimmers and switches to reduce or turn off lighting. I have 17 5200L 5000k lights on 4 dimmer switches in a 23x29 plus 3 more in a 6x15 bump out on one side and think it’s just about the right amount of lighting.

The plan is to split the overhead lights onto two dimmer switches, specifically alternating fixtures onto the 2 switches, so I have effectively full control over the lighting. I can't imagine the U-Shape with 8-10 fixtures wouldn't be enough light in my garage, though. Just want to be sure I am not under-spec'ing the lighting in any obvious ways.

 

[cybrdyke]

Reflectance is a huge part of the result. Default is usually 80/50/20, but it really depends on the materials on those surfaces. To use the default, you would assume a drywall surface painted white and a concrete floor. Then, the IES file of the fixture that you choose will work within those parameters.
It looks like your ceiling is open, which will reduce the "80". Try taking it down to 50. Cabinets and benches, etc, against the walls will reduce the middle figure somewhat, but remember that they have their own reflectance value. Floors can be new or old, clean or dirty, etc....Again, adjust the figures accordingly.

To your eyes, there is not alot of difference between 80fc and 100fc. I doubt that you could tell the difference by looking around the area. The difference will be in eye strain or visual comfort over several hours of use each day. So many people over-light their garages to 100fc that dont really need that much. If it was a full time auto shop and the mechanics are spending 10 hours a day in it, then yes, 100fc is a good figure. If it's a personal garage, then it's not really necessary.
CD

 

[TurboEuro88]

Thanks for the response. I had read in a few places that 100fc was the "go-to standard" which is why I had targeted it. Based on this and the tweaks youve suggested I think 10 makes most sense, and I may even be able to get away with 8. I am planning to get the concrete floor expoxied a light gray color in the coming months so that will help with reflectance as well. This is my personal garage where I'll mostly just be messing around and working/washing/cleaning my cars. I will probably appreciate the reduced eye strain as well.

 

[Platonic Solid]

Your unfinished ceiling reflectance is correct at 20. 93fc at 30" workplane is IES recommended for automotive mechanical work spaces. That's intended to be 93fc after all your stuff is in there. Hence aiming for 100fc in an empty space makes up for some of the loss experienced after filling the space. How much you personally are most comfortable in depends on your visual acuity which is typically related to age. If you're 50+, aim for the higher side.