# saving money on heating with some algebra

Time for some math..

Let’s make some VERY rough estimates:

1. heat is on from 8am to 12pm normally (16 hours a day) and off completely at night.
2. using a unique under-desk heater pane (link below) while I work in the evenings would reduce whole house heat needs by 2 hours.
3. but the panel costs \$66 and uses 150 watts
4. avg heat bill per month is \$300 (I have no idea… just a guess)

So that means…

\$300 * 2/16 = \$37.50 saved per month by turning off the heat for 2 hours of 16 per day

150 watts * (1KW /  1000 watts) * (\$0.20/ KWh) * 2 hrs * 31 days = \$1.86 per month spent on electric heat

So ~\$36 saved per month

So the break-even point (on cost) is N months

\$66 = \$36 * N
N = 1.83 months

You could also do the break-even analysis using “primary energy” used to account for the difference between
electricity used vs heating oil, but I am happy enough with this.

BTW… the reality is that the overnight temps on cold nights drop dramatically and the furnace turns on a bit to keep
the house at 58F which I think is about the limit for comfortable bundled up sleeping.  So that’s factored into the 16 hours.

I’ll report back on how it goes.

Related:

1. This is why zoned heating is useful

2. Gary at builditsolar.com does something similar with an electric mattress for sleeping, but I would personally be worried about EMF with it right next to one’s body…  LINK  (\$’s saved/year \$186)