I'm building a house in Northern Europe (-25C / -15F). Those are both the default options here too. Modern air source heat pump systems (e.g. Daikin Altherma)

I'm building a house in Northern Europe (-25C / -15F). Those are both the default options here too. Modern air source heat pump systems (e.g. Daikin Altherma) are quiet due to variable speed compressors, work in heat pump mode down to -25C and have built in backup heat if it goes below that.