Where I’m at, the temps flip-flop day to day, even hour to hour. In the morning it’s 35° outside, and by evening it’s 79°. I gave up keeping up with the temps and shut my unit off for the time being.
My question is why can’t HVAC units be programmed to say that if the outside temp reaches n° and the inside temp reaches m° cold, turn on the heat; conversely, if the outside temp rises to n° and the inside temp reaches m°, then turn on the AC?
My thermostat already knows the outside and inside temp, but I still have to manually switch it back and forth. I want a system that I can just set it and forget it all year round.
Most HVACs thermostats have a target temperature range and can toggle heating and cooling to stay within that range - usually with some minimum range logic to prevent constant swapping.
This is also a classic modern house problem. In areas with wild temperature sways like what you’re describing traditional house building would include hacks to capture and retain the cool air in the morning and shed as much excess heat as possible during the day.
When we lived in Puerto de la Santa Maria we’d throw open windows to create a cross breeze in the mid afternoon and keep the air flowing (assuming it didn’t get too cold) into mid-morning at which point we’d seal off the east facing windows and draw curtains over the windows and doors to keep the heat out - swapping to full enclosure as it got to just before lunch time - then opening east facing windows and leaving the west shut util it was time to start the cycle again.
It was unbearably hot in direct sunlight during the hot months but the house stayed cool - especially with thermally conductive tiles and stone being the primary exposed surfaces. As long as you properly cycled the house you could keep it comfortable and it was easy to adjust by airing it slightly less or letting more heat in.
Wooden houses with huge sliding glass doors in direct sunlight that have no shades or curtains can’t do this, however.
My friends family has a shore house we’ve gone to a few times. It’s an old house, built before a/c was a thing, and still doesn’t have any. We throw open some windows and the house stays pretty comfortable, it’s warm but not at all unbearable even when the temps are in the 80s, 90s, occasionally even over 100 (fahrenheit of course)
It does help that it’s at the shore so there’s basically always a nice breeze.