DOE announces breakthrough in residential cold climate heat pump technology
There is plenty of opportunity in being more efficient.  To give an example, houses in the Bay Area has gray/black roofs.  In the summer such roof receives about 10kW of energy and readily converts it into heat.  Heat, which we are trying to evacuate from the house with our super-efficient heat pumps in the air-conditioning units.If only we'd painted these roofs with white reflective roof paint (~92% reflection).  We would have removed ~8kW of heating from such roofs!  And then, maybe, we wouldn't  have to pump all that energy into air-conditioning.  So the surrounding air would be cooler, less noise would be heard from air conditioning, less energy would be spent.   And the cost?  4 gallons of white reflective paint and a couple of hours of work, painting the roof...