The Myth of “Energy Efficiency”: Are We Measuring the Wrong Thing?

A recent piece raises a question worth thinking about if you're planning heating or cooling upgrades: is "energy efficient" actually the right goal? The author argues that efficiency only measures whether you're avoiding waste while doing a task — it doesn't ask whether you're using the right kind of energy for that task in the first place. His comparison: you wouldn't use a sledgehammer on a thumbtack, yet homes routinely use high-intensity heat sources for jobs that need only mild warmth, and call it efficient because the equipment itself wastes little energy.

The piece points to hot water as an example. One reader comment noted that a well-insulated, well-sealed house (sometimes called a "pretty good house") might only need water heated to 85–95°F for space heating, while a natural gas boiler is really only necessary once outdoor temperatures drop below about -13°F. Below that, a heat pump can usually handle the job using far less intense energy. Another commenter cautioned that domestic hot water is different: it needs to stay above 140°F to prevent Legionella bacteria from growing, so lower temperatures aren't always safe.

The discussion also touched on gray areas — how heat pump performance depends on your electricity source, and whether efficiency will matter as much once more homes pair with solar panels and reach net-zero energy use. There's no single verdict here, just a reminder that matching your system's intensity to your home's actual heating and cooling needs may matter as much as any efficiency rating on the label.