While visiting some friends in Canada this summer, I couldn’t help noticing the proliferation of heat pump compressor units on the outside of homes. The reason, I discovered, is two-fold: huge subsidies that reduce installation cost for homeowners, and new technology that makes the pumps far more efficient during the long winter months.
Heat pumps, in my view, are one of the top five most important innovations necessary to convert a house from fossil fuel to solar-generated electricity in any climate. Others would include insulation, air sealing, efficient appliances, smart thermostats, and hybrid electric water heaters.
So it’s critical that heat pumps not demand as much power as traditional electric resistant baseboard systems still found in many older homes.
On the latter point, not all companies have taken the same approach. Mitsubishi, for example, uses a process called “flash injection,” to reintroduce refrigerant back into the circuit in two different places in its latest heat pump offerings. This allows the compressor to keep operating at high speed at 100 percent efficiency, down to about 5 degrees Celsius. This Hyper-Heating INVERTER Technology also incorporates a variable speed compressor. This is another critical upgrade as homes move toward renewable energy, not only for heating applications, but also for cooling.
Installing heat pumps to replace natural gas and oil-burning HVAC equipment won’t automatically wean us from fossil fuels, however. Many utilities that produce grid electricity still burn coal, a major CO2 polluter. Heat pumps, like electric vehicles, have almost unlimited potential to reduce our CO2 emissions, but only if their energy source is renewable.
As I’ve written previously , the prospect of solar-powered air conditioning and heating taps tremendous interest from would-be buyers, and for good reason. Self-sufficiency in the form of sun-powered HVAC appeals to a wide demographic. The technical hurdle until recently has been the surge of power required when compressors start (for cooling), and the inefficiency of battery storage for heating.
Variable speed inverters solve the former challenge nicely, and partially address the latter as well. A motor that ramps up incrementally will be less likely to overtax or damage a home battery system. Unless the solar array is indirect (feeding to the grid, but not the home), it will depend on batteries to smooth out the inconsistencies of solar power generation. And at night, or when the sun’s not shining, or during a power outage, it will need that battery storage to keep heat pumps running.
Canada’s success in discounting and distributing air source heat pump technology offers a success story on a massive scale for U.S. policy makers and manufacturers. Rewarding homeowners for kicking their fossil fuel dependency by subsidizing heat pumps has proven an effective strategy.
The Housing 2.0 program is made possible by the generous support of building industry leaders, including Mitsubishi Electric, ZIP System, Panasonic, and Schneider Electric.