(Part of the No Sweat Solutions series.)
As almost everyone who studies the subject concludes, one key to reducing greenhouse-gas emissions is efficiency. Renewable sources generally provide energy at a slightly higher market price than fossil fuels. Oh, there are exceptions: passive solar heating, wind electricity, biofuel from waste. But overall, if we get all our energy from low-emitting sources, we will spend more overall per BTU. If we can use those BTUs efficiently, our overall energy bill can be the same or lower.