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> The framing (at least as I understood it) was more on the psychometric side - 24C@65% relatuve humidity _feels_ worse than 27C@45%RH

It's complicated to quantify, but in a sense 24C@65% is warmer than 27C@45%RH. Or rather, maintaining your body temperature is more difficult in the former than in the latter.

The human body produces ~100W of heat, and the primary way to get rid of it in warm weather is evaporative cooling: at below 100% relative humidity water slowly evaporates, this takes energy and thus cools down the surface the water was sitting on. We use that by coating us in sweat and letting it evaporate. This is more efficient the lower the relative humidity is.

The attempt to quantify this in a nice metric is the wet bulb temperature (what would a thermometer with a wet cloth around it show). 24C@65% is a wet bulb temp of 19.3C, 27C@45% is a wet bulb temp of 18.8C

> Sadly, I am unaware of Nest and/or Ecobee's support for this sort of a setup. Probably not cost effective for them. :\

I've got both of these. Nest has a setting for 'cool to dry', but my climate is usually not humid and hot at the same time. I don't see a similar feature on the Ecobee, but the Ecobee app is perhaps more confusing. It does send alerts when the detected humidity is above set points. Where I do have issues with humidity is in my basement; typically the basement stays around 5-10 F less than the first floor, and if the first floor is 50% relative humidity, moving the air into the basement results in a much higher relative humidity. If the a/c is running for the first floor, there's a good chance of significant condensation on the vents right after the air handler.

>Sadly, I am unaware of Nest and/or Ecobee's support for this sort of a setup. Probably not cost effective for them.

Ecobee has a setting to enable this: https://support.ecobee.com/s/articles/How-to-use-AC-Overcool...

They also have a setting to adjust the temperature for humidity: https://support.ecobee.com/s/articles/Adjust-the-Temperature...

Right, I wasn't specofic - Ecobee will overcool with the main AC, but it does not have the 'I have a dehumidifier in my HVAC setup, go use THAT' setting.

> Sadly, I am unaware of Nest and/or Ecobee's support for this sort of a setup.

Same, and the worst part is that Nest already includes a hygrometer to show humidity in the app. All they need to give the user is a toggle: setpoint in regular dry bulb temperature, or setpoint in calculated wet bulb temperature (or heat index or "feels like" or whatever user-friendly calculation). Although their remote temperature sensors don't have a hygrometer, only the main unit.

Part of this is solved by sizing the ac correctly. Too powerful an ac and it doesn’t cycle as often and humidity builds.

Another option is a variable speed condensing unit. This is what I am looking at doing next.

A dedicated central dehumidifier is nice, but I've found them to be kind of noisy, especially when installed in the attic. Its got its own compressor, so the vibrations will transfer into the structure.