I only really know about it in the area where I live. AC was not generally included in new construction in the San Francisco Bay Area until the 1980s or 1990s. I wouldn't be surprised if a majority of apartments in the area still didn't have AC, based on the amount of window AC units I see.
However, most homes built in this area were built central ducted heating systems since the 1950s-1960s, when there was a massive building boom. Most older homes have had central heating added as a retrofit decades ago -- even old Victorian homes. So when people upgrade to AC today, it's very common to just use the same ducts.
It's not easy to find a house with a ductless mini split AC system around here. Most homes have a single-zone central system that cools the entire house.
twblalock|5 years ago
However, most homes built in this area were built central ducted heating systems since the 1950s-1960s, when there was a massive building boom. Most older homes have had central heating added as a retrofit decades ago -- even old Victorian homes. So when people upgrade to AC today, it's very common to just use the same ducts.
It's not easy to find a house with a ductless mini split AC system around here. Most homes have a single-zone central system that cools the entire house.