This summer i want to be more efficient and save money on my AC usage because I can remember last year it was an disaster. For example, on a typical 100 degree day, the highest the temperature would read on the thermostat is about 85-86 degree around 5pm without any AC, all windows and shades closed. Last summer I set my thermostat to 81 degree and the AC will kick on right about 3pm when temp start to go above 81 degree. And then every 15 to 30 min. or so, the AC and fan will constantly turn on and off. I usually run AC for 4 hours from 3-7, then we open all windows around 8pm when nightfall.
Below are the options I can think of, which one is more efficient and cost effective?
Set the thermostat at 81 degree and keep fan on for four hours.
Set the thermostat at 79 degree and fan auto for 3 hours.
Set the thermostat at 78 degree and fan on for 1 hour then wait another hour and turn AC back on fan on for another 1hour.
My system is Lennox G16 Q3-50 Furnace and I think a 1.5 ton ac outside.