We’ve been meaning to replace our furnace — an old oil heater that was converted to gas back in the ’70s — for years. It’s big, it’s ugly, and worst of all, it’s inefficient. So we pay much more for heat than we’d like, even in Seattle’s relatively mild winters.

gas furnace But new furnaces don’t come cheap. In fact, some back-of-the envelope calculations a few years back convinced me that it could take nearly a decade before the savings on our gas bills paid for the up-front costs of a new furnace.

In theory, of course, that’s still a pretty good investment. After 10 years, we’d stop paying for the furnace, and it would start paying us.

But in practice, we never seemed to be able to save up the cash. Maybe it’s my upbringing (my dad was hilariously stingy), but I hated the thought of going into debt, and paying interest and financing costs, just to buy an appliance.

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On reflection, though, the fact that we waited to buy a high-efficiency furnace proves one thing: I’m a dolt. You see, if I had financed the furnace — i.e., bought it on credit, or taken out a homeowners loan to pay for it — the amount that we saved on utility bills each year would have just about equaled our annual payments. Which means that I could have had a nifty, high-efficiency furnace years ago, without paying a bit more for heat (utilities + financing costs) than I did with our old clunker. Less climate-warming emissions, no extra costs.

I think there’s a general principle in play here. Consumers (like, er, me) are generally pretty foolish about energy-efficiency investments. We pinch pennies on the purchase price, even if it means that we overspend on energy over the long haul. Most businesses — even energy-intensive industries — do the same thing.

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But if there were an easy way to finance energy efficiency investments — say, a loan fund that would let homeowners and businesses use energy savings as collateral — then virtually everyone would win. Consumers would spend less on energy; manufacturers would see their sales shift away from cheaper models to more expensive ones; and the loan fund itself could turn a steady profit. Oh, and we also might not heat up the planet so fast …