Leaving a light on overnight, how much electricty/$$$ am I wasting?

In My Humble Opinion
1

I leave the light over my kitchen sink on overnight, in case I want a snack, or need to navigate in my apt. How wasteful is this?

2

Depends entirely on what kind of bulb you have in that light fixture.

3

If you are concerned about the electricity used, you can buy a motion sensing LED nightlight.

4

This is trivial to calculate if you have the wattage of the bulb and the price you pay per KWH of electricity (neither of which is in the post).

5

We need to know the wattage of the bulb. Then, the calculation is trivial.

Electricity is sold, typically, but the kilowatt-hour. If you have a typical 60 watt incandescent bulb that is on for 8 hours per night, that’s 60x8x365 kilowatt-hours per year, or 175 kilowatt-hours per year. Electricity in the US averages about 12 cents/kilowatt-hour, so we’re talking ~ $21/year.

You could cut that significantly by using a High Efficacy source like fluorescent or LED.

6

J-P, I like your idea! :smiley: I can check the wattage, yet to get 1st electric bill.

7

Or get an LED night-light for somewhere in your kitchen; maybe not enough to make a sandwich by, but enough to keep you from walking into the stove on your way to the light switch. You may also be able to pick up motion-sensing ones which wouldn’t even be on all night, but just get turned on when you get up. This has the dual advantage of freaking burglars out.

8

Correction: That’s 60x8x365 watt-hours per year or (60x8x365)/1000 kilowatt-hours per year.

9

A 1 watt LED bulb would take 1000 hours to consume 1 kilowatt of electricity. There’s about 8760 hours in a year - give or take a leap year. So if electricity costs 10¢ per kilowatt in your area, that’s about 90¢ a year if the light is on full time.

Of course a 100 way bulb would waste about $90 a year, but that’s one BRIGHT bulb for a kitchen. Still a 60 watt bulb would use about $60 a year.

So figure about a dollar a watt per year per bulb left on and you wont be too far off especially considering:

  1. You’ll wear out the bulb quicker and have the cost of replacing it.
  2. You’ll keep the house warmer in the summer and need more AC especially if you are using old incandescent bulbs. Not so true with LEDs and CFLs though.
10

My wife likes a lot of night lights.
We had a fluorescent “bright stick” over the sink that was on 24/7.
At 33W, it was costing us around $30/year in electricity.
I replaced it with 12W of LEDs, saving around $20/year.

So, even the little loads add up!