That’s because fully electric furnaces do not lose any heat through venting gas, so they are all considered high-efficiency. But an electric furnace isn’t the same as a heat pump. Heat pumps ...

It’s easy: You’ll see a gas supply line and exhaust flues. Low-efficiency gas furnaces will vent to the roof ... for areas with mild winters or high gas utility rates.

But, here's where she says things get complicated, "High efficiency heat pumps in warmer climates typically use less source energy on average compared to gas furnaces. In colder climates ...