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Outdoor Lights Can Be Activated by Motion

June 27, 1993| Produced by the Energy Extension Service, a division of the Washington State Energy Office. and

QUESTION: I'd like to automate my outdoor lighting controls to have the lights come on only when they are needed. Are there any outdoor lighting fixtures or security lights that will keep the lights off during the day, but turn them on at night when someone enters the area?

ANSWER: Yes, most home improvement stores carry outdoor fixtures that have photocells as well as motion sensors built in to optimize the use of energy. They range from $20 to $40.

Motion sensors, which detect movement and turn lights on as objects come into the target area, are often used in conjunction with photocells for exterior applications. The photocell prevents the light from coming on in the daytime regardless of motion in the area. And the motion sensor prevents the lights from being on all night.

These units activate only in darkness, to greet you with light as you enter driveways, walkways and entry areas. They also turn the lights off if they haven't detected any motion for a set time period, usually 3 to 10 minutes. Some sensors will allow you to adjust the time period as well as the sensitivity to motion.

These fixtures come with incandescent bulbs such as halogen or standard flood lights that, though not as efficient as compact fluorescent lights, are better suited for this application.

Heat Mirror Glass Can Save Energy

Q: I've heard of Heat Mirror glass. What is it?

A: Heat Mirror is a trade name of the Southwall Corp., referring to a unique type of low-E glass. Low-E stands for low emissivity, and is a coating applied to glass to reflect long wave infrared heat. This means heat from a room will "bounce off" the low-E coating like a mirror. The benefit is warmer glass and less heat loss during cold weather.

The R-value of the glass, or its resistance to heat loss, is increased 30% to 60% with low-E coatings, depending on the specific product. In the summer, low-E glass can reflect outdoor heat before it enters the window, keeping the home cooler. All major window manufacturers offer units using low-E glass. Typically, it is sandwiched between two panes in an insulated glass unit. It is soon becoming the industry standard.

Low-E coatings can also be applied to various types of thin films and suspended between panes of glass. Heat Mirror utilizes a low-E coated Mylar film in between two glass panes. It has the benefits of both low-E and triple pane glass, and therefore higher R-values than standard low-E glass. Heat Mirror glass may also be tinted, reflected or clear. Cost for Heat Mirror will be higher than standard low-E glass, but the increased comfort and energy saving may be worth it.

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