Energy Math at 2 Charlton Street

WHAT CAUGHT OUR EYE. How 2 Charlton Street lowered the cost of hallway lighting from $9,586 to $604 per year.

It begins with Chris McGinnis, board director and energy sleuth extraordinaire of 2 Charlton Street, a 16-story, 175-unit co-op in Greenwich Village. Always on the hunt for energy efficiency, he noticed the light fixtures in his hallway and realized he didn’t know what kind of lightbulb they were using. “So I took a chair into the hallway,” he says, “undid the three screws in our lights, and took a picture of the light bulbs and ballasts with my cellphone.” After some Googling, he learned they were compact fluorescents. He knew these were more energy efficient than incandescent bulbs, but he also knew that LEDs were better.

And then what? “I just kept digging,” McGinnis says. He found out how much energy each of the fluorescent lamps and ballasts consumed, then he began calculating how much it cost to light the hallways with fluorescents. It was a four-step math problem, juggling watts, days, hours, and number of fixtures.

Bottom line. McGinnis figured out that his co-op was spending $9,586 per year to keep the fluorescents burning brightly 24 hours a day.

Yes, but, do you really have to keep the hallway lights on all day? The answer, McGinnis discovered, is yes and no.

Behind the scenes. There are city regulations stipulating how much light hallways actually need, but it’s not bright bulbs 24/7. There is also the matter of how much electricity costs at certain time periods during the day, and whether your rate is residential or a demand-service classification.

• The hallways of 2 Charlton were being billed under a demand service classification, which meant that during peak hours they were being billed expensive peak rates. 

• McGinnis projected that the hallways were empty approximately 20 hours a day. 

Expert advice. McGinnis says, “So I knew what we had, but I didn’t know where we could go.” He turned to En-Power, the energy consultant 2 Charlton had used for other efficiency projects, for next-step advice. En-Power double-checked the math and recommended a bi-level LED fixture manufactured by Remphos. This fixture would dim the lights when no one was in the hallway, but as soon as someone entered, the lights would brighten to full strength.

The big reveal: Installing bi-level LED lights slashed the electrical consumption for each fixture by about 90 percent. This translates to an annual cost of $604 to light the hallways, down from $9,586.95 with fluorescents. 

Takeaway. In the world of energy conservation, it’s a truism that you have to spend money to save money. That’s why energy gurus talk about how much time it will take to see a return on your investment. The total project cost about $42,450. Con Edison gave the co-op a rebate of $12,900, and 2 Charlton wrote a check for $30,000. Each year the co-op will be saving about $9,000 in electricity charges, bringing its payback period to about three and a half years.

Just do it. Everyone in energy efficiency circles talks about “low hanging fruit.” These are the easiest and most cost-effective projects to do. While many people might put a discussion of hallway lighting into the often contentious lobby/hallway design arena, there’s no denying it can offer a quick payback that will cut operating expenses year after year.