The apartment building we own has "common" lighting in the hallways and stairwells. Lighting accounts for our largest share of electricity. I've worked over the years to reduce the lighting costs. Here is how I reduced our lighting expenses by a whopping 90%.
Pursuit 1: 70% savings by moving from CFLs to LEDs and reducing bulb count
My first pursuit was to simply transition from CFL lightbulbs to LEDs. LEDs are generally lower wattage than CFLs, and given the extraordinary reliability of quality LEDs, I no longer needed in-fixture bulb redundancy.
I happened to come across a set of Energy Star certified Cree LED bulbs and used them to replace all of the old CFLs.† This reduced the building's lighting expense by about 70%. This change also greatly reduced my labor costs, because the CREE LEDs have been 100% reliable for the past 6 years, unlike the old bulbs which needed to replaced every year or so. The reliability of the CREE LEDs have been so high that over the past six years, we have needed to replace a grand total of zero CREE LEDs.
Pursuit 2: 35% more savings with a Lighting Photosensor
About a year later, I got to thinking: all of our common areas have larger windows, so we didn't really need electric lighting on bright days. Therefore we installed a Woods photosensor, so that all the indoor common lighting automatically turn off on bright days, and then automatically turn back on when it gets a little dark. This change reduced the lights-on time from 24 hours per day to something more like 16 hours a day (depending on the weather and time of year).
This reduced the building's lighting expense by about 35%, bringing my total lighting cost reduction to about 80%.
And then a Pause...
After implementing the above changes, I couldn't think of a new way to reduce costs. I left the lighting as-is for 5 years. It worked, everyone was happy, and our costs were low. But a few weeks ago I bought a pack of 3 Watt Sunco LEDs for my own home, and I got to thinking....
Pursuit 3: 50% Savings with Lower Brightness LEDs
The common areas only need to be bright enough for navigation, and lower brightness bulbs use significantly less electricity.
I replaced all of the 6 watt CREE LEDs with 3 watt SUNCO LEDs.† The CREEs were still working great, but by reducing the current brightness 40% cut the power costs by about 50%.
Overall Savings: 90.25%
All together, I've reduced the building's lighting costs by a crazy 90.25%. Instead of spending $500 a year on lighting electricity, we now spend $49 a year. Or another way of looking at it: Over the next 5 years these changes will save about $2300. That's an incredible savings, and it was stupidly inexpensive and easy to implement.
Recommendations, and Next Steps
One thing I did right in all this is that I bought quality, long-life Energy Star-certified LEDs. I would never buy any non-certified LED again, as I do not want to be in the light bulb replacement business. I have had bad experiences with non-certified mystery-name bulb brands, with fading phosphors, flickering, and just outright failure. My strong recommendation is to stick with certified bulbs that support dimming and all-weather use, using the principle that robust bulbs will last a very, very long time.
At this point I cannot think of another way to further reduce our lighting costs. I suppose one option is to install a very smart occupancy sensor, but I imagine that would have to wait until we do some major electrical work. Let me know if you have any additional ideas.
Since I have optimized my lighting costs, I will next focus on reducing the load of some of our remaining large energy consumers, such as the laundry equipment.
† we kept all the working bulbs taken out of service, and have used them elsewhere.