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What isn't there to like about sunshine? We like sunny days over cloudy, rainy, dreary days. It's a proven fact that humans have more energy and feel better about themselves when the sun is out. There is a reason, after all, why the suicide rate is so high in cloudy, rainy Seattle, for instance. There are other reasons to like daylight, especially as it pertains to buildings: sunlight makes for a better scene (key in retail applications), it saves energy and operating costs, and it is said to reduce our impact on the planet.

Studies do show that shoppers linger longer and buy more in naturally lit environments, students do better on tests, and office workers are more productive and absent less. And, of course, energy costs keep skyrocketing. In fact, energy costs are surpassing salaries and benefits as the number one cost to businesses. So, it makes sense for daylighting technology to flourish, right? And to be effective, daylighting needs good controls.

"Controls are the key component for both lighting and daylighting and they have come a long way in just the past couple of years of making the transition from lighting to daylighting more seamless," says Earl Houston, ceo, Ciralight.

The good, no bad and no ugly

Good daylighting is the result of an integrated design process, which includes the building design, installation of the right materials and controls that make the system work. According to the Energy Center of Wisconsin, good daylighting design can include elements such as concepts of lighting power density, illuminance levels, contrast ratios, window-to-wall ratios, ceiling to skylight area percentages, and reduction in glare. Good daylighting principles can vary among geographics, building design and climate. It is a mix of art and science.

But what makes good daylighting? From the controls sense, it is the ability to save energy costs and provide the right amount of light during the day — as noted seamless light. With that, there are four basic types of controls:

1. Schedule-based.
2. Occupancy-based.
3. Personal control.
4. Daylight-based control/harvesting.

The objective of the daylight-based controls is to turn off lights in areas with abundant daylight or dim the artificial lights as natural light increases, says Eddie Hickerson, staff marketing specialist, lighting controls, Square D. In the end, energy is saved.

"Savings can be 20 percent of 30 percent via occupancy sensors, for instance, so savings can be significant," Hickerson notes. He adds the savings can even reach 80 percent.