My 80-by-55-foot shop, which has an 18-foot-tall ceiling, is lit with 18 eight-foot-long, high-output T12 fluorescent lamp (FL) fixtures. Although I have a 15 kW solar-electric system to offset my electricity use, I’d like to reduce my lighting load. But when I’ve compared lumen output of other “efficient” lamps, they still draw nearly the same power. Is my lighting as efficient as it gets?
Dave Zabokrtsky • via email
At this time, it’s difficult to improve on the efficiency of straight-tube FLs. They still are the most efficient technology for illuminating large spaces. But you do have a few energy-saving options to consider.
If your fixtures are mounted directly on your 18-foot-high ceiling, the least expensive option might be to lower the fixtures so they can be closer to your work. Then you can simply remove lamps from each fixture as needed to save energy. If your lighting is not zoned, another inexpensive option might be to zone your lighting onto separate switches so you can illuminate only the areas you are using at any given time.
If those options aren’t possible or don’t save enough energy for you, your choices start to get more expensive. You can upgrade your current T12 lighting to more modern T8 or T5 fixtures and lamps, but the energy savings could take years to offset your investment. (The 12, 8, and 5 numbers refer to the diameter of the tubes, in eighth-inch multiples).
LED options with improved efficiency are now available to replace 4-foot and 8-foot FL fixtures, but they are also expensive and not usually available at your local big box store.
Will it be cost-effective for you to switch your 18 FL fixtures for new, more energy-efficient replacements? For that decision, you’ll have to weigh your energy needs against the cost of lighting retrofit options.
Dan Fink • Buckville Energy Consulting