Passive heating

The cheapest way to heat your home is to let the sun do the work for free!

If your home has north-facing windows, make sure (evergreen) trees or bushes do not block the sun.
Also, passive heating has a lot to do with heat retention, for which effective insulation is paramount, as well as stopping draughts.
For info on how to make the most of passive heating, go to SmarterHomes or if in the process of designing, renovating or upgrading your home, go to Homesmarts and ConsumerBuild