Fellow engineer here, with an interest in green building and HVAC.
Being an engineer I still can't give up on the idea, so I'm trying to come up with a design for something that will help. I'm thinking if there were something like an AC window unit except that it took outside air and just filtered/dehumidified it, then you could cool your house at night using a lot less electricity.
Here's a previous forum post on dehumidifiers. Unfortunately, dehumidifying outdoor air takes more energy than cooling low-humidity indoor air.
Window A/C units do save energy because people use them less.
West-facing windows matter, too, not just windows facing the equator.
Reduce loads, in rough order of importance:
Put
external shades or awnings on west-facing windows; internal shades are a lot less effective.
Seal and insulate your ducts, especially if they are outside the house's conditioned envelope, double especially if they are in the attic.
Air seal your house to reduce infiltration, which adds to both latent and sensible loads. Pay attention to all the usual culprits, like can lights.
Insulate your attic.
Put external shades or awnings on windows pointing toward the equator, especially those facing more westward.
Grill food outside or put a slow cooker in the garage instead of cooking inside.
Reduce electrical usage overall. For example, turn off the computer when not in use.
Keep showers cool and short.
Turn off fans when no one is within the air stream, otherwise they are heaters.
Use smaller, well directed fans rather than large-area fans.
Don't exercise inside.
Improve comfort:
Shorts, tank tops, linen, no socks or shoes
Bed fan for sleeping
Don't use blankets
Webbed or woven furniture rather than furniture with pillows
Eat less hot food
Popsicles
Why would leaving air conditioning running all the time cost less than say, turning it on in the evening so you can sleep well, and off the rest of the time?
Because most people don't understand simple heat transfer principles, and that AC units are either on or off. They are not variable.
Mini-splits are variable and are more efficient at lower speeds. Otherwise, you're right.
