It's been a very mild winter but not mild enough to halve our electricity bill, that´s due to the heat pump we had installed before Christmas. Our house is way warmer but costs less. OK, the heat pump wasn't exactly cheap but it's not just about money, right?

Northerners and physics students all know about heat pumps but when I talk to my friends in the UK they don't seem to have heard of the possibility of using one to heat their houses. It's like air conditioning in reverse. Ours takes heat from the cold air outside and puts it into our warm house. The way it works is the same as a fridge,  gas expands in pipes that are in a box on the outside of our house. When the gas expands it cools below the outside temperature so heat flows from the cold air to the even colder gas. The gas is then compressed with a pump, this makes it hotter than the warm inside of our house so heat now flows from the gas to our house. We pay to run the pump but the heat is free.

Some people say you can't use solar power in Norway but we are, it´s the sun that heats the air outside, even though it only -5℃.