Hmm, here in Europe were I live 27C would be considered a rather pleasant temperature. Anyway, sealed houses are not only good for keeping the heat in but also to keep the heat out. If you cool your house sufficiently during the daylight hours that should prevent it from heating up too much even after you stop cooling it (after sunset).
But if you absolutely must use active cooling after sunset you might want to get something like Ice bear 20 ( https://www.ice-energy.com/technology/ - i'm not affiliated with them just an example) hopefully it should solve it once and for all.
Bear in mind that 80F is a typical overnight low in most parts of TX during the summer, particularly in most of the heavily populated areas. Typical high temps during the summer months are mid to upper 90's or higher. Most of these same areas also have relatively high humidity, so it feels even hotter and can take quite a while for the temperature to drop even after the sun sets.
I've never been to Texas but a Wikipedia article ( https://en.wikipedia.org/wiki/Climate_of_Texas ) suggests that 80F low occurs only in Galveston in July and it's more like 60s and 70s elsewhere. If a humidity is such a problem then you could run dehumidifier during the day and that would lower humidity ( in a sealed house ) overnight.
I mean these temperatures don't strike me as particularly intolerable. I wonder if it's the case of keeping up with Joneses as in "my house is cooler than yours". There are some reports ( https://www.theatlantic.com/magazine/archive/2015/07/saudis-... ) that rich Arabs in Saudi Arabia are running air conditioners at temperatures that require sweaters — even when they go on vacation. Which is really amusing for these of us who come from colder climates.
Interesting, I wonder how people survived before the advent of modern air conditioning. 35C/95F should be fatal at 100% humidity (as your body can no longer shed heat).
> Interesting, I wonder how people survived before the advent of modern air conditioning.
I believe that there used to be many fewer people (absolutely and relatively) living in the southern US. Then air conditioning was invented and people realized they could get away from the sometimes brutal winters in the north without having to be miserable in the summers.
> Hmm, here in Europe were I live 27C would be considered a rather pleasant temperature.
There are many factors that influence how tolerable the heat is - low humidity and the presence of a breeze can make a huge difference on how tolerable 27C is.
But if you absolutely must use active cooling after sunset you might want to get something like Ice bear 20 ( https://www.ice-energy.com/technology/ - i'm not affiliated with them just an example) hopefully it should solve it once and for all.