Daylight Harvesting: Greening Your Home with Ambient Light
May 17, 2017 - 12:54:17 PM
Photosensors like these are nothing new. In fact, cities and private facilities have been using them for years to manage outdoor lighting. For instance, it’s likely that the lamps on your street rely on photosensors to switch on streetlights once the sun goes down.
Unfortunately, lighting a home isn’t like lighting a highway. At home, lighting serves many functions—from aiding high-precision tasks like cooking or writing, to providing decorative warmth in the form of ambient light. That’s why automated lighting controls need to be that much more precise. After all, it’s no fun to have your lights suddenly dim when you’re eating breakfast. But more robust, WiFi-connected lighting systems and sensors are giving homeowners a lot more control over their daylight harvesting—and saving energy, too!
Does Daylight Harvesting Actually Save Money in Residential Applications?
Manufacturers have been enthusiastic about the ability of daylight harvesting to reduce energy expenses in commercial buildings. There, lighting amounts to as much as 25 percent of a building’s average energy use. Manufacturers of daylight harvesting units claim that its installation can save businesses 20 to 60 of their consumed energy, although this number has yet to be conclusively verified.
Residential sites spend conspicuously less of their energy on lighting, in part because many already make use of ambient daylight through home windows and other openings. In fact, according to the Center for Climate and Energy Standards, homes typically only use about 12 percent of their annual energy consumption on lighting.
However, smart lighting—although challenging—presents fewer challenges than automating other systems and appliances throughout the home. Lighting is either on or off—or appropriately dimmed, if you choose to add that feature to your daylighting system. Meanwhile, an HVAC unit is the number one energy consumer in residential households, and automating them poses a challenge. That’s because heating and cooling efficiency depends on the airtightness of the home, as well as its ventilation, along with a number of other factors. In essence, outfitting homes with photosensors and other environmental controls for lighting may be a good place to start to introduce occupancy sensor technology to homes. And those applications could have far-reaching implications for your energy bills!
How Are Daylight Harvesting Systems Constructed?
The only downside to daylight harvesting is that you’ll usually need a pro to help set up your first system. Systems come with many variations. Will yours be open-loop, meaning it only accounts for natural daylight? Or will yours calculate the real light levels by sensing both electric lighting and daylight, using what’s known as a closed-loop system?
You’ll also have to decide whether you’d like the lights to simply switch off and on at certain levels, or whether they should be on dimmers, too. A lighting expert can provide you with light ranges that make sense for automatic dimmers—as well as how long the dimming process should last and other variables, like whether you’ll be able to override the automatic controls with your own situational preferences.
Of course, that’s a pretty advanced system. Most homeowners get started with daylight harvesting systems simply by installing occupancy or vacancy sensors throughout their home. Many of these are essentially motion detectors, and they’re usually used for overhead lighting. When they sense that someone is in the room, they turn on. No more motion in an area? They turn off. It’s a handy invention if you tend to leave a room absent-mindedly, without switching the lights off. And the Department of Energy estimates that lighting controls like these can save up to 30 percent of the wasted electricity spent lighting rooms that no one is using.
More advanced smart lighting systems feature a touchscreen controller that allows you to create lighting “zones,” grouping the overhead kitchen lights with the task lights below the cabinet, for instance. You can also create “scenes,” designating which lights come on, and their intensity—and some cases, even their color—during a particular situation. So you could create one called “party,” setting your system to dim all the overhead lights to 30 percent and turn on outdoor lighting, for instance.
One day, we’ll probably even see controls like these integrated into even more advanced automated situations. For instance, you’ll be able to turn down the lights, turn on the TV, lock the doors, and microwave popcorn, all through voice command. That’s still in the future, but more advanced smart controls are making it seem more and more like a reality every day!
Erin Vaughan is a blogger, gardener and aspiring homeowner. She currently resides in Austin, TX where she writes full time for Modernize, with the goal of empowering homeowners with the expert guidance and educational tools they need to take on big home projects with confidence.