Heating a Room for 8p per day

[Skvez]

A candle flame produces about 15W of heat
I can't follow the link to confirm what sort of candle they showing (As the link is down at the minute) but a typical tea-light candle lasts for about 3 hours
So four of them would produce 3 * 4 * 15 = 180Wh
Which is the same amount of heat you'd get from a fan heater running for 5 minutes.

So certainly they produce heat but they won't make much of a dent in a big space.
You'd need it to be a very small room if you wanted to feel much difference.

By contrast an inactive person produces about 100W of heat just sitting still (Reading a book or using a computer) and potentially much more if they’re actively doing something.