Earlier quoted context omitted.
Climate change is both: 1. A slow and steady increase in the average temperature. 2. A rapid increase in the frequency of extreme weather events. Point 1 doesn't force people to buy ACs, but Point 2 will. For example, you generally don't need AC in San Francisco, but a heat wave in 2017 killed 14 people[0]. As the frequency of heatwaves increases, people will need to equip themselves against the temperature _extremes…
I’ve definitely personally seen the affects of climate change. Many people should be able to same the same who have lived decades in the Southwest US. Fires are more common, they’re more often extremely damaging, record setting summers year after year, and so on. As a side note, I’m offended by the commenter above you. As if someone else is going to be able to tell me what I’ve witnessed over the course of my life.
Rather than being offended, I think it would be more persuasive to others if you were able to quantify what you've witnessed.
You imply that there are buildings that did not need air-conditioning when constructed, but do need it now because of climate change. I don't know what the answers are, but let's consider what statistics would be useful to defend your statement.
First, since you are talking about air-conditioning, we can probably restrict to summer temperatures. It's not clear if we can look only at daytime highs, since higher temperatures at night are also uncomfortable. Since we're talking about a threshold, we can probably restrict to the single hottest month. For Phoenix (and I'd guess the rest of the Southwest?) this looks to be July.
So to tell a compelling story, you'd probably want to show that the average high or average low for July has increased significantly since the time the building was built. How much is significant? I don't know, but if the claim was that it didn't need AC when built (as opposed to saying that it needs it more often now) I'd think we'd want to see a change of about 5F (2C). There might be a good argument for a lower number (perhaps humidity has also increased?), but it likely would be less convincing than a large jump in temperature.
Finally, you'd want to show that the increase in temperature is due to climate change, rather than the effects of urbanization. More blacktop, more buildings, and more air conditioners (!) will increase the number on the thermometer in an urban environment even if the climate hasn't changed. On the bright side, most published temperature records have already been adjusted to remove these Urban Heat Island effects. But do realize that your perception that it is hotter might be affected by the build up of the environment, so the temperature either needs to be measured outside of urban areas, or adjusted for the non-climatic changes.
So instead of taking offense, could you perhaps point to a historical chart of July temperatures for where you live, showing that the temperature (adjusted for urbanization) has increased significantly since the buildings were built?