> But this all falls apart near and below freezing temperatures. There are heat pumps designed for cold climates that work well into the -30C range or so still

> But this all falls apart near and below freezing temperatures. There are heat pumps designed for cold climates that work well into the -30C range or so still holding a COP of 2 or more. Here are some test results from Finland from a few years ago https://www.scanoffice.fi/vttn-testiraportit-ilmalampopumppuvertailu/ https://www.scanoffice.fi/vttn-testiraportit-ilmalampopumppu... (Lämpökerroin = COP) And if one is doing it at district level just pump the heat from the ground or sea where the temperature stays the same all year around.