Candle power

[bunsen_h]

A few weeks ago, when kattale was having furnace problems, I suggested that lighting a bunch of candles might help to keep a room warm. I got to wondering how much difference it might really make.

The rough calculation isn't all that difficult, especially with information available on the net.  IKEA's stick candles come in packs of 4 with a shipping weight of 0.4 kg, or packs of 6 with a shipping weight of 0.6 kg, and burn for about 9 hours.  Ignoring the packaging weight, that's about 100 g / candle.  Paraffin wax has a combustion energy of about 42 kJ / g.  (100g / 9 hours) * (1 hour / 3600 seconds) * (4200 J / g) is pretty close to 13 J/s = 13 watts, per candle.

Compare with the heat output of a sedentary human -- which varies widely, but let's say 1500 kCal / day, or 73 watts.

It'd take a lot of candles or people to generate the heat output of, say, a 1500W space heater.  But in an enclosed space they do add up.

Comments

[buttongirl.livejournal.com]

Plus flame has a psychological effect of looking/'feeling' warm in a way that a space heater never can.

[kattale.livejournal.com]

So what would it be with beeswax pillar candles? (Which is incidentally what I used...)

[bunsen-h.livejournal.com]

The energy-per-weight-burned for beeswax is probably similar to that for paraffin -- there are some significant differences in their chemical structures, but both consist mostly of long hydrocarbon chains. So the crucial factor is the weight-per-time burn rate, and that depends a lot on the wick. If you have information about how much the candle weighs and how long it takes to be completely burned, without leaving more than a tiny bit of wax behind, I can calculate the heat output. (Or if you've got the volume/dimensions of the wax that's burned, the weight can be calculated from the density of beeswax.)