A pal forwarded me a post from a UK website promoting “practical solutions for self reliance”, describing how you can “heat your room for 8 pence a day” using tealight candles. (For those on this side of the Atlantic, 8 pence is currently about 13¢). They describe burning tealights under flowerpots as a “cheap and easy alternative” to standard heating methods.
Easy? Maybe. I guess it’s easier than starting a fire in the wood stove. But cheap? Turns out, not at all. I investigated the cost of tealight-heat. Here is what I found:
The cheapest tealights I could find in a quick search were these on Amazon— $28 for 500 (5.6¢ each). Each weighs 0.3 ounces. To be generous, lets assume that’s all wax. Wax contains 18,621 BTU per lb. If you burn up the whole box of 500 tealights, you will extract 174,572 BTU (again, being generous and assuming you manage to burn every bit of wax out of each tealight.)
Now, those BTU’s are equivalent to 51 kWh of heat, or, say, running an electric space heater on “low” (500W) for 100 hours. Around here, electricity is about 14¢ per kWh. So 51 kWh would cost… $7. Thus, we find that electric heat is about one-fourth the cost of tealight heat.
As an alternative way of looking at it: if we assume a tealight burns for about 2 hours, it burns with same heat as is produced by a 50W lightbulb. The tealight costs 2.8¢ an hour to burn. But the lightbulb is only 0.7¢ an hour. And gives off more light.
Moreover, candles are not especially good for indoor air quality. And if you spring for non-petroleum, beeswax candles, you will be paying even more.
Conclusion: candles are an expensive way to get light or heat. They should be reserved for power outages and romantic dinners.