It's expensive here because when a heat pump is heating, it's basically the same thing as turning a window shaker around backwards and then running it. Although the ground loop lets you cheat your starting point to about 55 degrees.
Also, when you put 100 heat pumps in a school or hospital, the customer will need to replace compressors more frequently than they want to. With conventional air handlers and VAV units. there is a lot less to go wrong. With regular air handlers you also get a lot more control. You can modulate a burner but you can't modulate a compressor beyond stage 1 / stage 2 unless it's a centrifugal unit which you'll never see scaled smaller than huge.
Natural gas is dirt cheap right now too and is predicted to continue to be dirt cheap. The coal industry is hurting because natural gas prices have dropped by more than half in the past few years.
Radiant heat is the way to go in my opinion if you live anywhere that actually gets cold in the winter.
