A lot of us have been trying to figure out how to get a solar photovoltaic system for producing our own power on top of the roof of the Co-op. But, the first step in any home or business renewable energy project is conservation, because every watt that we avoid using is one we don’t have to produce. For instance, home solar installations start with lowering consumption by replacing older, less efficient electric appliances, because efficiency in these devices has risen dramatically in the last 20 years. The saved energy – sometimes called “negawatts” – is the most environmentally friendly way for us to transition to a cleaner power economy, without adding solar panels, wiring, breakers, or any other new equipment made from new materials that would have to be mined and processed.
Light bulbs are electric devices that take electricity, measured in watts, and try to convert it into light, which is measured in lumens. Older, incandescent bulbs were measured in watts – think of a “100 watt bulb” – and they work by super-heating a piece of metal until it glows, meaning that most of those watts actually become heat instead of light. Industrial and commercial spaces have traditionally used fluorescent light bulbs (the kind where a fixture has a few tubes four or eight feet long), because they do a pretty good job of converting electricity to lumens. Unfortunately tubular fluorescent light bulbs are unattractive, and their ballasts can hum and interfere with other electrical devices around them. The light color of fluorescents is also a poor match for human vision. So, even where they produce the same number of lumens as an incandescent bulb, the light quality isn’t as effective for things like reading.
LEDs (Light Emitting Diodes) are effectively solar panels running in reverse. They directly exchange electrons for photons and are probably the most efficient form of lighting we can ever have. LEDs work on the photoelectric effect, and the specific quanta of light matching an electron energy level was how quantum mechanics was named; formulating this effect was how Einstein got his first Nobel Prize. The “band gap” of the semiconductor material inside is what controls the color of light that LEDs put out and, unlike many other forms of light, a given LED device will only put out exactly one wavelength or color of light. LEDs lose very little energy in the conversion process to heat, which is why we use LEDs in all sorts of electronics that we can touch.
Lighting Efficiency: How the Co-op Is Improving
Rick Mausert, Honest Weight’s Chief Cooperative Officer, initiated a fluorescent lighting replacement project to install more efficient T-8 form factor LED bulbs in the place of the existing T-8 fluorescents. These bulbs can be used in the existing fixtures but don’t require the existing ballasts. They produce a color of light that’s, lumen-for-lumen, better for human vision. T-8 form factor LED bulbs typically need replacement after 50,000 hours of use, compared with 20,000 for the fluorescents.
You might be wondering, how can a building that we just opened in 2013 already need a major change in its lighting for more efficiency? The answer is, technology changes rapidly. Below is a brief overview of how far it has come in just the last decade.
A decade ago there was a big push to move away from incandescent bulbs to compact fluorescent bulbs (CFLs, the bulbs that look like white spiral tubes). CFLs contain some mercury, take a moment to turn on or warm up, don’t work well with dimmers, don’t work well in the cold, and produce a light that many people dislike. They reduce the power used by the traditional bulbs by 80 percent, so when they were first introduced there was a big push to adopt them. But their odd shade made them difficult for people to get used to, so research continued into other forms of bulbs. In the last few years, affordable LED lights have been produced to serve as replacements for traditional bulbs of all kinds, from the Edison sockets you screw the old incandescent bulbs into, to the fluorescents that fit into a long rectangular ballasted fixture, and even traffic lights.
When we had the new Co-op building constructed, LED lighting was in its infancy—but it’s now ready for prime time. The Co-op’s new LED installation will give about a 20 percent efficiency gain over the older T-8 type of fluorescent bulbs, for a projected savings of 127,125 kilowatt-hours a year and an annual savings of $7,120. This retrofit was supported in part by a National Grid incentive, so the out-of-pocket cost to Honest Weight for the project was $26,000, with a payoff time of a little over three years. This also avoids up to 181 tons of carbon emissions (assuming we’re getting our power from a coal plant). The fact that they are more attractive is just a side benefit. This is definitely one of the brighter ideas for making the Co-op meet the environmental part of the triple bottom line.