‘Tankless hot water heaters. No new home should ever have an old, energy-sucking tank style water heater – that’s like putting the engine from a 1985 Buick into your new car. Tankless water heaters are also called on-demand water heaters and heat water to the perfect temperature as it is needed, unlike tank style models that keep gallons of water piping hot 24/7/365 – even if you’re away on vacation which is a ridiculous concept. Want to go even greener?”

via The Best Green Home Upgrades of 2009.