The Egloo consists of a base, a grill and two terracotta domes. Candles can be placed on the base, and will warm up the domes when they are lit. The grill supports the domes and makes a space in which the candles can combust.
The inner dome is thinner and stores a high rate of heat, while the outer dome takes in cooler air from its surroundings — this results in thermal exchange, pushing the warm air out into the room.
The makers claim that after 30 minutes the Egloo will begin to heat the room, increasing the temperature by 2-3 degrees for up to five hours with four tea candles. Which doesn’t sound that impressive to me for human warmth but could make a difference in, say, a glasshouse. There are plans to make this larger and the makers are claiming it’s eco-friendly – not sure how that can be when you’re burning candles and releasing all those hydrocarbons that are allegedly so bad for us?