Daylight harvesting, once deployed only in large commercial and industrial settings, is getting lot of airtime with home builders and renovators. The process is just like it sounds: You install a combined window treatment and lighting system that coordinates the amount of heat and light that comes through your windows into living spaces. It's not a difficult job to coordinate the window louvers and blinds with dimmer switches on your lighting fixtures - with a computer!
As more and more homes are built or retrofitted with master controlled lighting and thermostat systems, we'll find features like automatic dimming, daylight harvesting, and clock timers that measure ambient light and make adjustments. In short, your house wakes when the sun comes up, opens its eyes (louvers), harvests the light, and pops on the heat as necessary.
At noon, when the sun is brightest, your dimmers turn down the inside lighting fixtures and make the most of the sunshine. When partnered with a thermostat, the windows and lights of your home perform an elegant juggling act based on outdoor/indoor temperatures and sunlight that adds up to high energy efficiency.
Daylight harvesting and green lighting
According to Energy Intelligent Systems & Technologies (Enestec), several studies show that daylight harvesting produced cost savings for electric use as high as 60 percent.
The harvesting process is not that complicated. It involves the use of an ambient light meter that triggers computer-activated adjustments to combine ambient with artificial light to hit the level set for each room in the house. During the warm and summer seasons, the system closes louvers to reduce solar heat and block harmful UV rays.
To coordinate the effort, the system uses photo-sensors, control modules, dimmers, and fixtures that aim the louvers and focus light directly where you want it in the room. This can be especially helpful when dialing in each room depending upon the direction faced by the exterior walls.
Taken independently, each of these components alone can assist with your energy costs. When pricing, dimmer lighting tends to cost more than on-off switching. And programmable thermostats cost more than static models. But when added to the right types of windows for your climate, they add up to a greener home and lower utility bills.
So far, the adoption of a complete daylight-harvesting, climate-control system for residential use has been slowed by high installation and product costs. But there is little doubt that the harvesters are coming.