Motion Sensors ROI
As commercial building managers have known for years, another great way to save energy is with motion sensors. When it comes to your home, a motion sensor can be a good idea for hallways, porches and outdoor spaces. How much you save depends on how often you use the light, but let's say you are a typical user, and putting a motion sensor on your hall light means it is only on for a few minutes after someone walks by.
Let's say this cuts down the amount of "on" time by 90%. Instead of $16 a year for our fixture, we are only spending 10% of that, or $1.60. We would also be vastly extending the life of our bulb, so that saves us an additional 75 cents in the first year (more later). A basic motion sensor kit from a big box starts at $15, so this pays for itself in a shade over one year.
Note that for many fixtures, the motion sensor comes built in, so you may want to calculate based on the specific price premium over an equivalent unit without the feature. Wee find that $15 is a reasonable estimate if you don't have the numbers available.