Start by converting all yr lights to CFL's, then step up the pace by re-wiring certain light circuits to Photovoltaic panels, moving on to a solar geyser - go for a glycol heat exchanger rather than a vacuum system(integrity of the vacuum is important over time), then harvest yr rainwater in a 10,000l tamk & feed it into yr mains with a pressure activated submersible pump (connect downstream of yr meter & watch yr municipality scratch their heads as you use 30% of yr usual water, bearing in mind that yr sewerage is charged as a % of the water used, your bill falls across the board)lastly, if by now yr neighbours haven't had you committed to Groen Dakkies, install a domestic Bio-Digetsr from AGAMA & generate enough gas to cook on for 4 hrs a day with only the contributions from a family of 4 as feed stock. This is a sunken under ground unit & has no smell & all the water that flows post the digestion process is great for yr garden & lawns - (Hey Buurman, why is yr lawn so green? Ja nee swaar, I irrigate from my loo, boet - LOL)You connect all yr water - Shower, bath, baisin, sewerage & washing machine into it. Basically you just dig a hole & connect yr existing sewer line to the unit.Total cost of my retrofit was R1,200 for the bulbs, transformers etc; R2,395 for the solar panels & deep-cycle battery; R15,746 for the rainwater harvesting system; R18,645 for 3 geyser solar heater; R9,000 for the bio-digester & about R500 for fittings etc. I did all the labour myself with my trusted "Horticultural assistant" - it took about 2 years to do it all. So I say - BE THE CHANGE YOU WANT TO SEE... Forget payback periods, just do it !!!