1) Never allow direct sunlight to enter your home while running A/C. The “greenhouse effect” can easily overpower your equipment. Keep shades closed and use artificial light when necessary.
2) Unless they are located in or near the ceiling, A/C vent louvers should be angled upwards, as colder air drops.
3) Windows should be kept closed unless the air temperature or humidity, preferably both, are lower outside.
4) Attic fan thermostats should be set at 110 degrees; ensure the attic also has adequate vents to avoid sucking cool air from your living space, and that doors and hatches to the attic remain shut and well-sealed.
5) Clean or replace intake filters regularly. This is also important to maintain high indoor air quality.
6) Keep vents closed in unused rooms.
7) It will save energy to turn off or turn down A/C if you will not be home for two or more hours.
8) Since cold air drops, all central A/C vents in the basement should be shut and sealed. Sealing is done most effectively by placing a cardboard or plastic cover completely over the vent, secured by two-sided tape or glue. In my experience, flexible magnetic covers are not strong enough to withstand the air pressure and must also be secured with tape or glue. Even after doing this, your basement may still be the coldest room in the house. If the furnace is located in the basement, during heating season you may find it provides enough heat for the basement without opening basement vents, so you might be able to leave the vents sealed year-round.
9) If you sleep on an upper floor, if possible A/C should be shut down on floor(s) below you (leveraging the same concept as above).
10) If an A/C vent is beneath a window: do not block the vent with long curtains. This is to avoid trapping cooled air between the drape and the window, which is very wasteful. If you already have drapes that you want to keep, drapes can be pinned up on bottom, or the vents behind them should be shut and sealed.
11) Use of a fan in your bedroom will enable you to raise the A/C thermostat by at least two degrees, while maintaining the same level of comfort and using less electricity overall.
12) When using an exhaust fan or central vacuum, crack a window closest to the source of suction. This is to avoid pulling outside air from the path of least resistance (which may be your attic) through your home. Remember to close the window when done using the equipment.
13) If a door to a room gets sucked open or closed while running A/C, the airflow is inadequate and air will be pulled from outside, or worse, the attic. The solutions are to either cut the bottom of the door to allow air to flow freely, or leave the door open.
14) When bathing or showering, open a window in the bathroom and run the exhaust fan if so equipped. Keep the exhaust fan running and window open for 10 minutes after bathing.
I look forward to your feedback and additional tips.
Stay tuned for tips to save on heat, in the Fall!