I was partially inspired to make this thread from some comments I saw in another thread about air conditioning. Anyway so how common is air conditioning where you live, in my area pretty much all newer buildings built since around 1980 or so will have AC and heat. Older buildings were generally designed for heat only at the time of construction but most have had some form of air conditioning installed later on. The summers here can get quite hot and humid so most people opt for air conditioning unlike most of the other parts of Canada or even Ontario.

For houses, almost all homes built after the mid 70s or so are equipped with central forced air heating with a furnace and so either came built with air conditioning or is relatively easy to retrofit air conditioning to. Older homes generally used cast iron radiators for heating, fed with hot water or occasionally steam from a boiler in the basement or in some cases electric baseboard style heaters. Some have had air conditioning installed, generally with window mounted units for a cheaper install or a mini split type system. Unless the homeowner is doing a major renovation, the cost of installing a forced air central system is too costly and messy.

Apartments/Flats here generally didn't come with air conditioning until the 1970s. The heating in the older buildings is from radiators/baseboard heaters fed with hot water/steam/electricity. Some higher end buildings might have had "built in" AC units under the window but most required the tenant/owner to install their own window mounted unit. Newer apartment buildings generally use a hot/chilled water system with fan coils located within each unit. Those use the same fan coil for heating during the winter and air conditioning during the summer.

Schools depends on when they were built, generally pre mid 80s schools are un air conditioned, and newer ones generally have air conditioning. I went to a elementary school without air conditioning and the second half of May, June, and the first half of September are brutal. Often times the teacher would shut off most of the classroom lighting to lessen the added heat (it wasn't that effective).

Public transit is mostly air conditioned now, aside from the subway stations. The last un airconditioned train, streetcar/tram, and bus here were withdrawn from service in 2012, 2019, and 2011 respectively.     

Here at Idaho, my one of old house build in 1900 and it used to have 1 wood small stove and 1 diesel space heater (pot burner) that shares with two main vent masonry brick fireplaces for heating. (Now only one primary big wood stove and the 1970's electric 26kw heater with A/C furnace was never full finish install) It don't have fiberglass/rockwool insulation back that time. it just wood planks and covered heavy with hand work plaster wall. The air condition system come in here later maybe 1970's big odd 3 ton R22 Freon system window style Fedders brand name sticking big ass out wall and it's loud compressor reciprocating when it running but it crazy colder than my friend's house that had R410 AC system when when summer heat wave hits. Also have rare early 1980's Fedders that could run A/C and heat pump mode that send waste heat up to external water heater tank. Also 1970's blue color water heater tank has optional solar exchange hot water for on roof (disconnected, need whole new piping repairs) with backup 2.5kw heat electric still working.  I could post some pictures on old appliances things in my house if anyone interested, I know its not related to LG but I do notice here some member here do like old things running in their home... but here bonus my house old style electric wiring still working "knob and tubes" that haven't upgrade for many years.

but here bonus my house old style electric wiring still working "knob and tubes" that haven't upgrade for many years.

That's cool that your house has good knob and tube wiring! My house is from 1951 and has the cloth coated wiring that is still good! My house was poorly wired though so my whole house needs rewired but I will save the wiring in the house if that ever happens.

That's cool that your house has good knob and tube wiring! My house is from 1951 and has the cloth coated wiring that is still good! My house was poorly wired though so my whole house needs rewired but I will save the wiring in the house if that ever happens.

My old cloth wiring alright for now but there few sections of cloth wiring in attic where mice, critter or starling bird attacked on it, I just use the rubber liquid electric tape it works but I don't like messy job. old wire was pretty thick as 10 or 12 AWG size.   

All homes here in Israel, have A/C units, mainly split ductless ones that are to be installed on the wall. They can cool and heat.
They looks like this: https://www.lighting-gallery.net/gallery/displayimage.php?pos=-125847

Our house has a new Carrier hvac unit outside. It really is not very effective. My worshop has a old GE window ac 12,000 BTU and it is very effective.

Around here, I would guess majority homes built after the mid-late 60s were built with central air and electric heat. By the early 70s it would have been standard.

I have noticed the older homes built from the late 1950s up to 1970 or 71 usually used the round 8" and 6" diffusers with rings in the center of the ceilings. Usually these had a knob or pull chain to shut off the air flow. I really liked these round diffusers as a kid. Homes built after about 1971-72 usually use rectangular diffusers along the edge of the ceiling.

I have seen one house built in 1995 that had round diffusers which was very unusual.

Some older homes around town used to have the old York a/c units outside that had the fan on the side. Haven't seen one of those in quite a while.

I am not sure what the older homes used for heating before central a/c. One of my friend's houses was built in 1930 and has the vents in the hardwood floors so I would guess that it had some kind of forced air furnace, but I really never thought about it. Some of the less fancy old homes also used oil burning space type heaters or convection heat, which basically was just in one room and sort of heated the whole house by convection currents.

Some old homes I can remember seeing the oil or kerosene tank outside which was like a sideways drum on legs.

All of the schools I went to had central air conditioning and electric heat. However, my middle school had one wing of classrooms that was 1940s era, and leftover from the old high school, and those rooms still had rows of old radiators below the windows with metal covers. They weren't used though, and instead wall unit air conditioning/heat units were installed on the wall.

Very few homes in my state have gas heat, even if they have gas stove and water heater. Some old trailer homes had gas furnaces, but these days they all seem to supply electric.

At the VOA transmitter plant-new York chillers have been installed.One for the control room and front transmitter halls.The other chiller for the office areas.Each chiller has 4 scroll compressors-replacing the reciprocating ones.The old chillers were Carrier-each of those had two recip compressors.150 ton cap each.Figure the new ones the same.The new York chillers are more efficient than the old ones-and use a refrigerant that can be easily obtained.The one ones the refrigerant was becoming expensive and soon to be NLA.

Here the aircon is not used that much. There are just few hot days over the year and because the winter and energy costs require the buildings to be well insulated, plus most common heat management techniques here are based on large thermal inertia (so allows to utilize the cooler nights to remove the heat from the structure by just open windows overnight and then hold the cold over the day), it is not needed that much.
But in new build houses it uses to appear more and more, as the equipment is getting cheap. But virtually only the ones built as heat pumps (so reversible), mainly when gas is not wanted or available (direct electrical heating gets VERY expensive here).