It makes sense to try to get your house to do most of the work for you without needing much energy at all. That may sound too good to be true, but it is not. Germany has done a lot of work on the idea of the Passive House, one which relies on its own intrinsic design as far as possible to meet its energy requirements (www.passiv.de). A house of this sort will have good insulation, will face south, and have the best level of glazing available. It will be airtight, will pre-heat fresh air with a ground heat-exchanger and recover waste heat from air leaving the building, and will use renewable energy to heat the water.

Perhaps a house like this is not an option for you, let alone one which keeps itself warm in winter and cools in summer as well, like the ancient wind towers of Yemen and other parts of the Middle East which are designed to make maximum use of natural ventilation. But you do always have the option of remembering how much energy went into building your house, how much it needs to keep it going in the style you have adopted, and what the scope is for saving energy – from not overfilling your kettle, to using

http://maps.grida.no/go/graphic/energy-cost-of-various-construction-materials1