I worked on a laboratory building in a cold climate recently. Labs typically consume a ton of energy (relative to offices/residences) due to the energy spent on

I worked on a laboratory building in a cold climate recently. Labs typically consume a ton of energy (relative to offices/residences) due to the energy spent on conditioning and forcing air for fumehoods. We investigated a couple of different ways of reducing energy: PV, wind, efficient HVAC systems, and Ground Source Heat pumps (GSHP). The GSHP reduced the energy consumption of our building by over 50%, where the rest were barely hitting 10%. I haven't personally seen it installed at a residential level, but if it's affordable (which, given cheapness of natural gas may not be) could be huge in cold climates.