While researching lighting options for my garage workshop, I discovered the online and free Visual Interior Tool
. I thought that it may be of interest to other builders who are designing lighting for their workshop.
I will be building in my two car garage measuring 25' wide by 21' deep. The present lighting is inadequate with two light sockets, one centered between the cars and the other near a wall over a laundry area. If I had no choice I could make that work, but it would be cheap and easy to install a few 8' fluorescent fixtures, right? Well, a few searches on VAF (where we have some lighting professionals contributing) convinced me to approach it with some added education and thought.
Here's how I used the Visual Interior Tool:
allow for Lux
, which are measures of light intensity. With some Google searches I found a professionally recommended light intensity for metalworking of 700 lux per sf, so I set the Units
to Feet - Lux
The tool only works with rectangular areas, so entering the Length
of my garage was straightforward at 25', 21', and 8.5' respectively.
is the height above the floor where you expect to be doing most of your work and therefore need the light. As my workbenches will be 3' high 3.5' seemed like a good estimate. (I noted after the fact that changing this value from 2' to 6' does not change the results.)
required more Google searches. My ceiling is flat and off white with most being unobstructed and therefore highly reflective. The walls are also flat and off white, but with shelving and other items covering much of it. The floor has a light blue, speckled epoxy finish. Based on these characteristics and my research I estimate the reflectivity to be 90% for the Ceiling
, 80% for the Walls
, and 55% for the Floor
. Unfinished cinder block walls and a concrete floor, for example, will have different values, but estimates can be found and confidence gained when similar from multiple sources.
As described above I found an Illuminance
estimate for metalworking to be 700 Lux.
No requirements for Power Density
. Under Constraints, per the instructions, I could have blocked off an area where I have a half bath, and you can impose a limit on the number of Rows
if there are obstructions on the ceiling, for example. I didn't need to use these.
Next I selected the green plus tab at the bottom and experimented with various types of fixtures. Fortunately Lithonia Lighting is one of a number of vendor options and their products are available at Home Depot, so I reviewed their products at homedepot.com while making selections in the tool. I did have to modify the Symbol Length
and Symbol Width
fields as originally the icons were squared and therefore the Calculation Results
such as Spacing and Arrangement
were incorrect. I used the product dimensions as shown on the Home Depot website.
I settled on the Lithonia Lighting 4 ft LED Strip Light, model MNSL M6. They're $119ea at HD but I found them for $101 elsewhere. That's not cheap, but they only require 18.5 watts, are rated to last 50,000 hours (23+ years!) and have a very high Color Rendering Index (CRI) of 89. CRI measures the ability of a light source to reproduce the colors of various objects accurately in comparison with an ideal or natural light source, 100 being optimal. Also, being in Florida I don't want lights that create a lot of heat.
I plan on installing nine of the LED lights as the row on the far left has a bathroom, washer/dryer and water heater below, in addition to a kayak hanging down that would block the lights. Per the results I should get 732 lux which just exceeds the 700 lux suggestion I found for metalworking. I also found a footcandle estimate for scroll woodworking of 70. Changing the units to footcandles and illuminance to 70 results in the same recommended configuration, providing some added confidence in the results.
I'm sure it's not perfect. The results are only as good as all of the estimates I made or borrowed from others. But, it should be a lot better than my original plan of simply putting up a few 8' T8 fixtures, and it gives me measurements for placement which should help coverage and minimize unwanted shadows. I was surprised to learn how much lighting is recommended, and with some of the fixture/lights I selected the configuration included upward of 30 4' fixtures!
I have an electrician coming to help, and plan to have the lighting, electrical outlets, and compressor each on a different circuit/breaker. I also plan to have multiple switches for the lights so they don't all have to be on/off at the same time.
Feedback is, of course, welcome, and especially from any of the pro's in the event that I am propagating any misinformation.