送交者: Enlighten 于 2005-8-08, 15:02:40:
回答: How much can it save each year assuming electricity or gas heats water now? 由 HunHunSheng 于 2005-8-08, 14:14:53:
the savings from energy does not cover the cost of the equiqment and maintainence.
Another example is the hybrid cars like the Toyota Prius. It is calculated that it takes 60,000 miles a year driving to get your money's worth, as compared to a Toyota Corrolla, which is similar in size but costs thousands dollars less.