[ScienceAlert] This time, we’ll look at space heating. In Melbourne you need it, if you don’t want to be the bad guy who goes around telling everybody to put on jumpers instead of heating the house. Our house is heated by gas, and occasionally by a wood fire. Space heating, as you can imagine, is one of the big energy users and also a big CO2 producer. In the pre-green ‘business as usual’ scenario, the central heating accounted for about one-quarter of our home’s CO2 production. We were using around 55 000 MJ (megajoules) per year.