The culture of building a house that helps humans endure the summer months at the expense of a bit of discomfort in the winter is easy for me to understand. Using independent fuel burners (in this case butane gas) and kotatsu (“camilla” tables and “brasero” heaters) are part of winter life in many parts of Spain.
What I have never seen in Spain is this contraption which combines both. Next time I have to spend the end of the year in Alicante I’m adopting it. Genius!
https://www.amazon.co.jp/IBF-省エネ温風パイ.../dp/B0012P3BMQ
EDIT TO ADD - MrLapLap just arrived back from a trip. He says this pipe method is used widely to funnel hot, dry air under and into futons. In the summer, futons are periodically placed under bright sunlight to dry out, disinfect and suppress mite and fungus growth. In the winter and in the rainy season this isn’t always possible and piped air from a fuel heater does a good approximation of sunshine’s job. (Those without fuel heaters can buy a dedicated electric futon dryer.)