Research suggests that heat-pump water heaters are by far the most energy-efficient option for most households. They're approximately three times as efficient as ordinary electric water heaters since they don't create warmth...they merely move heat out of the air and into the water.

(A gas, point-of-use device at each hot-water faucet approaches the same efficiency. But we're not on a natural gas line and didn't have to make that choice. Electric point-of-use hot-water heaters can't come close to heat-pump technology.)

Downsides of a heat-pump water heater include the high initial price tag (but look for rebates!) and the hum of a fan. Heat-pump water heaters also cool the air around them (great in summer, not so great in the winter). And they need a large, open area with a temperature that doesn't drop below 45 Fahrenheit for optimal performance.

I decided to give up a bit of square footage in my writing space for optimal, energy-efficient hot water. More on what we think of our high-class heater in a later post!