- A log-burner, and;
- Central heating over a pesky heat-pump.
- Radiant central heating using radiators and a heat pump.
- In a place that required it (cold and damp), some system primarily responsible for maintaining a suitable humidity.
- A server/switch-room.
- Exposed wiring, such as cable trays (although their acquisition of dust may prove inconvenient).
- A bidet.
- A shower with a ceiling (in a cold bathroom).
- Wood, stone, or concrete flooring.
- Less walls and less doors. But perhaps sliders like shoji (障子).