It all comes down to building techniques, insulation, airtightness, eliminating thermal bridges, &c. There are also many low tech solutions for heating/cooling, such as air/air heat exchanger couples with ground/water or ground/air heat exchanger at a fraction of the price and a fraction of the maintenance.
Of course the average american living in a mcmansion which wouldn't pass regulations in 1992 Poland cannot use such solutions, but really it isn't a problem of climate, you'll find passive houses from africa to norway and everywhere in between, most of them without heat pumps
