So I had an idea but I don’t know if it can be practical or not. With an extremely tight ICF home under .3 ach, could you not theoretically make a simple fresh air intake to cool your house even in hot climates. I live just south of Atlanta. At no time does the temperature not go under 70 at night. Could I use an outside temperature probe to kick on a dehumidifier with fresh air intake when the temperature is in range, say lower than house temperature down to 67 degrees. If the house thermostat is set to 74 do you think it is possible to not kick on? The rest of the time fresh air could be supplied by erv. I feel like this is the technical version of just open a window at night. Hypothetically it could be used in opposite fashion for heating in fall/early spring. I only ask because I am designing/building an offgrid house and the biggest power user is air conditiong. Our HVAC designer said we could get away with a 2 ton unit. We have talked to him about doing mini splits but being as many rooms as there are he thought itd be complicated to get the loading spread evenly.

you are going to be spending a lot of energy to dehumidify it in my mind. Just run the ac...

I am in Michigan and calculated a couple years ago that if the temp outside is 60 degrees or less the air doesn't hold enough water in it to raise the house humidity at all. So I have our attic fan programmed to open and run if the house temp is over 70 and outside temp is 60 or less (Smarthings controlled).... We are .78 ach so have a window that automatically opens when this is active. This window has a screen that catches lots of pollen and bugs from entering the house.

We cool our house on the hot days by running water though our heated floor circuit. Our well water is 50 degrees and all we have to run is a single sprinkler to cool the house. The water going to the spicket goes through the pex in the floors first. We use one of those tractor sprinklers and a 24 VAC valve to control the water. The thermostat controls the valve that cools the house. This cools a 3700 sqft ranch with a walk out basement that half the basement is completely out of the ground so we have a lot to cool.

I think we could have easily got away without an ac unit at all. We also heat the house with a single wood burner that exhaust heats water for the floors. Good luck and hope you save some energy.

I already have a pretty deep gusher of a well that has pretty cold water but how do you keep condensation from forming or is that not a problem with it being embedded in concrete? We planned on doing in floor heating with the amount of concrete figured it would hold temperature pretty well.

Funny you ask....I also have a fan coil on the well outlet that runs when the well pump runs. So, the water first goes through the fan coil and then to the floors and then to the sprinkler. It is nice because it waters the grass only when the house is hot which is also when the grass needs to be watered.

We try very hard to keep our humidity at 50% all year around in the house. It does get higher at the end of summer (maybe in the 60's) but not enough to run a true power hungry dehumidifier. I think in the last 2 years of having this setup we have ran our AC 2 times/days each year.(remember we are in Michigan 48105)

The house is a build block house with R30 on the upper level and R22 on the lower. I used an IR camera to find the air leaks and get to .79 ACH with spray foam. Ceiling was R30 but we upgraded it to R80 last Christmas.

We have 13k solar and if it weren't for heating shower water for the 7 people that live in the house we would be net zero. We heat water with NG.

A note about heated floors, the more efficient your house is the less the floors feel warm because they don't have to be as hot to heat the house.

We do get condensation on the well water pipes so I have covered most of them with pipe insulation but we don't get any condensation on the floors likely because as stated earlier the house is efficient and really doesn't need that much heating or cooling.

Also use ultrasonic mist and a house fan to humidify in the winter. If any one does this buy the single head units. I bought a expensive 5 head unit and it didn't last. If one head leaks the whole thing is trashed. You can buy the single head units for under $20.

We use Ecobees and some custom circuits to do the HVAC. We also use Smarthings to control some stuff.

We have made many mistakes over the years while building our last two houses so ask lots of questions. There aren't many people left on this forum but the ones that are or extremely helpful and smart.

Have a great day.

I've had my 4kw system for 6 years now and it's paid for itself 3 times over. I haven't had a power bill since it was installed. I have a great article for you about solar panels power - https://websolarguide.com/solar-pow...and-dryer/