There are also other products on the market such as passive infrared and sonic occupancy sensors that are built into surge strips so that electronics can be turned off when no one is in the area, but I find these products very hazardous to electronics and not very conducive to people coming and going from a room. They can work in a commercial or institutional setting, but should not be used in a residential settings unless they are properly factored into an overall design.
When deciding on where to put your sensors you need to take into account a couple of items:
- What kind of traffic does the room or space get during normal use?
- What kind of fixture or fixtures are present?
- What kind of luminary or luminaries do these fixtures use?
Looking at the room or space will help you understand the needs of the space and whether or not an occupancy sensor is conducive to your energy conservation goals. Rooms such as bathrooms, garages, laundry rooms, and closets are some of the best an easiest to figure out. Other rooms in your house may be a little harder such as bedrooms and living rooms; or just plain difficult like kitchens, offices, and family rooms.
Bathrooms are nice because you can put in an occupancy sensor to control the exhaust fan which will allow you to set an allotted time for the fan to run once a person has entered or left the room. Bedrooms may be a little harder due to high levels of usage, but can sometimes benefit from a manual "ON" occupancy sensor if people are prone to leaving lights on all the time. The rooms and spaces labeled as difficult are difficult due to frequent and infrequent usage that may not coincide with a sensors timer or range of motion. If you don't fully think it out you may end up with strange light shows and burnt out fixtures/luminaries in your difficult rooms and spaces.
Numbers 2 and 3 go hand in hand... different occupancy sensors work in different ways when it comes to light fixtures and luminaries that they utilize. First and foremost, you should always follow the guidance of the manufacturer's specifications when it comes to these products. All of these products from the sensors to the luminaries should be tested products (Underwriters Laboratories or other testing agencies), so that you know their limitations and how they should be properly used.
Fluorescent and compact fluorescent (CFL) luminaries do not generally work well with occupancy sensors and the life span of a fluorescent can be drastically cut due to some hard-wired sensors and most Edison base screw types. Fluorescent bulbs have a delayed start up time and cool-down period after being shut off which does not always work well with occupancy sensors. If you go in and out of a room with a sensor and you're using a fluorescent, you run the risk of the bulb burning out quickly or possibly burning out the fixture. Most Edison base type sensors explicitly require incandescent luminaries and some tested LEDs, but a lot LEDs also have a start delay similar to a fluorescent.
After digesting all of this information your finally ready to figure it all out and put together your plan. Even if you only install an occupancy sensor in one room of your house you can still make a difference in your energy consumption and waste. The code gives you a choice, but it never really tells you which is the better choice... at least now you know what one of those choices can do for you and your home.
One of the major manufacturers of hard-wired sensors is Leviton:
http://www.leviton.com/OA_HTML/ibeCCtpSctDspRte.jsp?section=10883&minisite=10026
For Edison base screw type sensors it's First Alert:
http://www.firstalert.com/HOME-SECURITY/OTHER-HOME-SAFETY/lighting
And there are a lot of others such as Wattstoppers, GE, and Z-Wave.
In Sacramento and the greater valley you can pick up occupancy sensors at any major hardware retailer and some smaller hardware stores. If you can't locate the right product you can always find it on the internet direct from the company or from any one of the many large internet retailers such as SmartHomeUSA.com.