News

Overlighting is passe, and costly, for businesses

Nina Winham
For bchydro.com

If you're operating overhead lights that were installed a few decades ago, chances are you're "overlighting." Not only could you save money by replacing your lights with new energy efficient models; you can probably save more by reducing your total light as well. Even better, you can improve the quality of your light (and your work atmosphere) as you cut those unwanted watts!

This is because the recommended standards for lighting – particularly in office (or educational) settings – have changed significantly since the mid-1970s.

"In the 70s, there was the energy crisis," says Cristian Suvagau, a senior engineer with BC Hydro who specializes in lighting. "The recommendation had been 1,000 lux [a measure of illumination on a surface] for an office desk, but lighting research shows now that upwards of 500 lux you kind of reach a plateau for the visual tasks of a modern office. That is, you can't tell much difference between 500 and 1,000 lux, and above 1,000 nobody would tell a difference even if it was 3,000.

"So they decided to go to a minimum recommended level, to help people think about how much energy they might be wasting, since the perception of light level is very subjective."

Suvagau says this led to more detailed and customized lighting standards (standards are recommended by the Illuminating Engineering Society of North America.

"They went down to 500 lux recommended for a general office setting. But then they said, 'If you're working at a computer with a backlit screen, and typing on a keyboard, you only really need 300 lux. You can add a desk lamp to bring it up to 500 for reading and writing.

"And you don't need 500 lux all over the office in places where people are just walking around; you only need 200.' So now, the recommended light levels are more customized to the real visual task you're doing – instead of just having a blanket of light blasted everywhere."

That means if you have older lighting, you stand to reap big benefits from upgrading. First, you can save a lot on electricity bills, by replacing older lights with energy efficient options. (BC Hydro will help with the upgrade cost, too, through the Product Incentive Program.) Second, you can save even more by reducing light in spaces that may be overlit. Finally, you'll probably find the new lights more comfortable."

"Up to the 1990's, fluorescent lamps only had a rudimentary type of phosphorous, so lights were poorer in rendering colours," says Suvagau. "The old lights gave a type of whiteness that was brutal. Newer lamps are better able to depict all the components of white light – red, green and blue, but the old ones could depict only one.

"So the whole visual process [with the older lights] was, 'I'm getting a visual impression, but because it's poor in its degree of white, and I always compare with sunlight or incandescent light, I think my eyes need more light.' With the new lamps, the whiteness is more broad spectrum, more like daylight. So then people say, 'I don't think I need so much light anymore.'"

Suvagau says tailoring "white" light to include more blue tones (like the light from the sky) can allow an even lower light level. "What happens is that blue is a colour that activates more peripheral vision in the eye, so technically the eye would not squint to see what it needs to see. The pupil is more open, and when it's more open more light will come in. So then you need less light – maybe only 10% less, but it still makes a difference."

It's a difference people may notice. Many companies that retrofit their lights say employees describe the new lighting as "less harsh," "brighter," and less likely to cause headaches.

Newer lights also use less energy because the quality of the reflective surface inside them has improved. While older paints could absorb up to 40% of the light produced, wasting energy, the newer ones absorb only 10% or less, meaning more light is emitted from the fixture for a reduced energy cost.

In the future, says Suvagau, office lighting may become even more sophisticated. Light levels influence your endocrine system, which helps regulate bodily functions. Providing a spike of light in the office in the morning and early afternoon (or on a graveyard shift) could help employees stay alert, much like providing a cup of coffee. Meanwhile, LED lights are continually improving in terms of colour rendering, offering more ways to influence visual perception.

For now, the message is that there's much more to lighting retrofits than just saving energy.

"Upgrading to more energy efficient lighting will save energy, but if it's just an energy upgrade it could be lousy. It has to bring you quality too, because lighting is about quality," says Suvagau. "Only a lighting practitioner will be able to help you determine if you're overlit.

"But when you're looking at upgrading, make sure you look at the whole system. Think about whether the visual task requirement in your workspace has changed. You might achieve a more impressive upgrade."

Learn more about improving your lighting efficiency and about rebates for lighting upgrades.

Nina Winham is a Vancouver-based freelance consultant and frequent contributor to bchydro.com.

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