Even here in southern Arizona, most homes do have central heat--but the Border Fort, which I built single-handed in 2010, does not. Part of the heating is passive solar in that the first six feet of wall height consists of a central 11-inch-thick core of earthbags filled with dirt left over from the septic leachfield excavation. The earthbags plus a thick outer coat of concrete stucco form a "pendulum effect"; during the day, the earth & stucco abosorb the sun's heat, then release some of it back into the home at night.
This keeps us comfortable (the home is seldom below 70 degrees and usually a bit higher) heat-wise, except for the colder months in winter, which seem to be averaging about 3 months of the year (minimum) to perhaps 4 months (maximum).
For those times, we have a ventless propane wall heater, NO fan (not wanting to depend on electricity), and it does the job well. The floor plan of the home is designed as an "open square", with no more than a 5 or 6 degree drop between the kitchen (where the heater is located) and my bedroom (at the far diagonal corner of the home).