A little more on heating/air conditioning.
Here in New England, there are a substantial number of homes built before a/c. And even after a/c was invented, there was a perception that it wasn't necessary here, because it only gets warm enough to need it a few months of the year.
Add to that the fact that most older homes here have steam or hot water heat, involving radiators, and no duct work for a/c. So adding a/c means running duct work, which means cutting holes in floors, ceilings and walls. Pre-1950s homes tend to have plaster walls instead of drywall and plaster is a little trickier to patch than drywall.
Plus, in order not to have ductwork running up and down the corners of rooms, the ducts tend to be hidden in closets. But older homes have much smaller closets (my 1900 house has a 38"x14" closet in my bedroom), and people don't want to give up valuable closet space for a/c. All in all, adding a/c to an older house is expensive--not just the cost of the a/c unit and ducts, but the work and repair work needed to get the ducts where they need to go. A window unit is a lot simpler.
As for radiators, I love them. The homes I've been in with forced hot air heat are simply not as warm or comfortable in the winter. As soon as the furnace shuts off, the room is cold. I heat my house to 62 degrees in the winter and I'm fine with a sweater. At Christmas, my brother, who has forced hot air heat, turns the thermostat up to 65 degrees, because we all complain about how cold his house is. We're still freezing, even with sweaters, long johns and throws.
The best are the old cast iron radiators. They give out such a comforting heat, and the radiator stays warm for quite a while after the furnace shuts off, so you don't get the heat/cold cycle that you do with forced air. But the baseboard hot water radiators are, I think, much more energy efficient, even though I don't like them because they make it more difficult to place furniture in a room.
Newer houses, say from the 1980s on, do tend to have central a/c. This usually means that they have forced air, and the heating/cooling systems share the same duct work.
It would be a rare New England house that doesn't have some sort of central heating installed. The ones I can think of are summer homes and they simply aren't used in the winter. And there are frugal folks who heat mostly with wood stoves, but most of them tend to have some sort of central heating as a back-up. Most of the older houses, even if they were built without central heating, have had it retrofitted at some point.
My house has oil heat, which is pretty common in New England. But the old coal cellar is still in the basement, from the days when there was a coal furnace that needed to be tended to a couple of times a day. The pipes are probably original to the house, but the furnace has been changed out a few times.
Central air on the other hand, is mostly in the newer houses.