Thursday, December 04, 2008


Some people have questioned whether using an electric space heater is actually better (more efficient, more economical, more saintly) than turning on my central heat. As a rough guide, I decided to compare the costs. Here are the results:

At current prices*, 1kWh** of actual heat in the house will cost 6.3¢ from oil (central heat), vs. 15.8¢ from electricity (space heater).

Obviously, heating the whole Palace with electricity would not be cost-effective. But so long as I am heating less than 40% (=6.3/15.8) of the house at any given moment, electricity becomes more economical. My kitchen "bunker" represents only 17% of the square footage of the house. My biggest bedroom represents 12%. My larger bathroom, 6%. So even if I had heaters going in all three places at once (35% of house) it would still be more efficient than turning on the furnace. So far, though, I've not had a heater going in more than one room at a time.

And, should oil prices return to their recent high point ($4.22/gallon, here) the balance point goes up to 80% of the house.


* $2.14/gallon for oil, $0.15/kWh for electric. Calculation assumes 98% efficiency for electric heater (approximate) and 83% efficiency for oil furnace (latest measurement).

** For visualization purposes, 1kWh is approximately enough energy to heat a big kettle of soup from refrigerator temperature to not quite boiling.


Blogger brushfiremedia said...

How much fuel is used to create 1kwh of electricity, I wonder.

12/4/08, 7:03 PM  
Blogger legallyblonde29 said...

What is the effect of leaving very cold rooms unheated next to warm rooms. The house is insulated only on the exterior walls. As a result, there is something less than 95% efficiency from the electric heat, I would guess, because some of the heat is lost to the unheated spaces nearby. Central heat would reduce this source of inefficiency. The alternative = insulating the interior walls or buying a much smaller house -- more like the Vermont house you posted about a while back.

12/5/08, 3:25 PM  

Post a Comment

<< Home