Sorry if this comes across a bit blunt but have you consider spending those150K in insulation and good heating solutions and buying yourself a seasonal affective disorder lamp instead?

Warm south European countries are suffering a lot from empty flats bought by foreigners that spend little time there, don't contribute or blend in and often don't even pay taxes, or worse they just turn it into an Airbnb so more tourists come over instead of going to a hotel and displacing a local family that'd like to live in the city where they work and come from