About forty years ago, A buddy came up with a loose unscientific formula that on a still night, a single candle burning in a 8 x 8 wall tent with flaps closed and bottom perimeter closed would warm the interior about 9 degrees over the exterior temperature. So if it was 40 degrees out and he wished the tent to be 67, he would need three candles burning continuously. Over the years, this seemed a reasonable guesstimation. Not that I wanted a bunch of candles lit, especially if sleeping, but one late fall rondy with wife and 2 small children and a freezing rain on a 10 x 10 wall tent, for an afternoon and evening we kept 6 candles burning and stayed above "see my breath" temps. ( I had a small wood stove by the next rondy). Just wondered if anyone had come up with a similar rule of thumb.
So the question is what type of candle?
There's a difference between a tea candle, a votive candle, and a stick candle,
and then with the stick candles, you have different burn rates depending on the diameter of the candle wick...
You can be more efficient with a terra cotta planting pot, inverted on the ground, and place the candle inside, with a small opening under the rim to allow air inside. The candle light is thus reduced, making it easier to sleep, and the terra cotta is heated which then radiates heat. Just be sure the kids understand don't touch the pot as it's very hot. After the candle burns down the pottery continues to radiate heat for a while.
LD