So, a while back I wrote a bit about our future building plans. Being in the midst of a southern California "winter," this is probably a good time to talk about climate control!
Permitting agencies will let you build a house without air conditioning, but not a house without heat.
The human can survive a lot of heat - you may feel like you want to die, but unless you are health-impaired and the conditions are truly hellish, most people will cope via applications of cold water, and/or chilled beer, and/or nudity.
Lack of heat, though is something that will actually kill you fairly predictably, especially if you are old. Improper sources of heat can also kill you.
One of the heat sources I've specced for the Sierra House is a wood-burning stove. The pros: the fuel is abundant and relatively inexpensive, and the truly cold season in our area is short. The cons: unless the firebox is perfectly installed and the house is very well vented, you can smother yourself with carbon monoxide. Also, hauling wood is tiring and can be dangerous, you can't store cut wood directly adjacent to your house unless you really want to issue an invitation to termites, and there is considerable associated mess.
So while this is a sentimentally attractive option and we may yet get one, if the budget allows, despite its potential drawbacks, it is only an option and not a Must Have. For ambiance, we may well go with a wall-mounted ventless gel-fuel fireplace instead: no wall/ceiling perforations and no special flooring required.
The more likely heat solution is also a cooling solution, and that is what's known as the ductless mini-split. This is a device that mounts on your wall and provides either heat or cooling via a compressor and heat pump located directly outside. These are cheaper than whole-house furnace/air handler/duct installations, more energy-efficient, and easier to maintain. Getting one of the smaller units for each floor of the house would provide almost complete comfort.
I say almost because again, we will be old. So there are additional heat options, focusing on the bathrooms.
There is a high likelihood that an old person is going to want to get up in the middle of the night to go to the bathroom, and for a solid portion of the year - much longer than the period when daytime heat might be desirable - the nighttime loo is going to get chilly. Chilly old people shiver and increase their risk of falling.
I have specced two heat sources for the bathrooms. One is a ceiling-mounted light + vent fan + heating element fixture; one is a hydronic box heater that can slide into the kickspace under a vanity. There is a good chance I will go with both of the then-available equivalents when we build. The hydronic heater can be set to a thermostat to keep the bathroom at, say, sixty degrees; and the ceiling fixture can be controlled via switch.
Of course, any power-consuming climate control devices have to be accounted for in the electrical wiring plan. Those two bathroom fixtures would each require a separate circuit. Knowing in advance how big of a circuit board to specify will help clarify the budget and will certainly reduce time spent on-site doing change orders and waiting for supplies.
Advance planning: the one-time home-builder's friend.