One of the first energy conservation tools I installed when we bought our town-home was a Leviton lighting occupancy sensor for the lights in our kitchen. We have 10 recessed lights for the kitchen (all CFLs) and I wanted to make sure they went off when it the kitchen wasn't being used. I explained how the device worked as follows:
The concept is extremely simple. When my Wife or I enters the kitchen the light comes on. When we leave the kitchen the lights go off (after a minute or two). The passive infrared sensor operates by measuring infrared light (heat) emitted by us as we enter into the kitchen. Basically, we alter the temperature when we enter the room and move around in it, and the device picks that up. If we come into the kitchen and sit down at the table to read the paper and don’t move for a few minutes, the light may go off because the temperature has stabilized. This requires the simple task of waving an arm.
And this worked well and good up until October 2010 (it was 2.5 years old) when the sensor started acting up. As you can see in the picture on the right, the sensor has three modes: Off/Auto/On. Off and On work just like a standard light switch would. Auto mode is where the sensor controls the lights. While in "Auto" mode, when nobody was in the kitchen and the lights were off, they would start flickering like strobe lights. Or the lights would be on and they would buzz and only come on half the normal brightness. Or they just wouldn't come on at all. If the mode was turned to "ON" the lights would look fine and work perfectly, so I determined either the sensor had gone bad.....or we had ghosts.
After ruling out ghosts, I decided to go to Home Depot and get another occupancy sensor. The only one I could find that said it could work with CFLs was a Pass & Seymour / Legrand sensor for $30. It is similar to this one on the Home Depot website and it is the one seen at the top of this post.
It is a little different than the old sensor from Leviton. Instead of an Off/Auto/On switch, it just has a button with a tiny LED in the middle of the button. Basically, it is always in "Auto" mode and the sensor works great. When the occupancy sensor senses motion, the lights come on and stay on for 5 minutes from the last motion detected.
What I like about this sensor is that you can easily press the button to turn the lights off when you leave the room. So if you walk in the kitchen to get some water, the lights will go on, but since you are only in there for a few seconds, you don't need them to stay on so you can easily push the button to turn them off as you leave. The motion detector will then stay dormant for 5 minutes, unless you push the button again to turn the lights on. The old sensor didn't have this capability! You could turn the switch to "Off" as you left, but then they wouldn't automatically come back on when you walked back in. On the old sensor, I used to try switching the lights to "Off", then right back to "Auto" while I got out of the way in hopes the lights wouldn't come back on, but they always did.
But there is a downfall to this new sensor! You can't set it so the lights will stay in the "On" mode. And this has recently caused a problem in my household.
My wife is studying for her Professional Engineer exam (she is also a Mechanical Engineer) at our dining room table. She likes to have the dining room lights on and the kitchen lights behind her on when she studies. Trust me, she knows I write a blog on energy conservation and how much torture I go through when lights are left on, but for me, her comfort trumps my energy conservation concerns (for all you energy conserving husbands out there who say it isn't the same in your household, I'm calling you a liar).
For instance, if she walks in the kitchen, the lights go on automatically. She then sits at the dining room table, but after 5 minutes the lights will go out again, and she will look at me and roll her eyes. There is no way to override the automatic function in the new sensor. Or another scenario, if it is the middle of the day and I don't want the lights to come on at all, I can't leave the sensor in "Off" mode. I can turn the lights off as soon as they go on, but I can't prevent them from coming on.
So what is the answer?
I think a combination of both of the sensors is the solution! One in which you can turn the lights off easily when you leave a room (like my new sensor that has a button) and a sensor that you can force to stay on when you want to override the sensor mode (like the old sensor which could switch to "On" mode). I just hope this new sensor lasts longer than the old one! It's hard to justify spending money on energy conserving devices if you have to shell out $30 every few years for a new light switch!