My Zoe keeps my toes warm all winter long, and it does it 30 seconds after I turn it on in -20 c weather. My diesel needs 10 minutes to warm up the cabin.
Heat Pumps work best above 40F (4C), and after that they are not very efficient. I don't believe that would be a good fit for an energy starved system such as an electric plane.
> Heat Pumps work best above 40F
[citation needed]
Have you ever experienced cold weather?
For year-round heating and cooling comfort, heat pumps work great in areas of the country with moderate temperatures. This is especially critical during the heating season. Once the outdoor temperature goes below 25⁰ - 30⁰ F, a heat pump can continue to provide heat. However, it will use more electricity to do so, which means higher utility bills. This is because there simply isn’t as much heating energy available as the outdoor temperature drops and the system will work longer to achieve the same indoor temperature. That’s why many air-source heat pump systems are installed with a supplemental heat source.
Source https://www.carrier.com/residential/en/us/products/heat-pump...