Hi @Yure,
I think I’ll need more context to understand what’s happening here. Adding the other load balance items (heating, cooling, etc) will help for context.
Is your space/spaces conditioned?
What does your geometry look like?
What’s the U-value of you constructions?
The window conduction seems to be behaving somewhat as expected, so I assume that your internal temperature is something reasonable.
Looking at avg high and low temperature for Texas it seems in peak summer it’s between 25-35degC. Doesn’t strike me as any opportunity for cooling from thermal mass, so unless your constructions have high mass and you’re running a low cooling set point overnight I can’t see that contributing.
My best guess from what you’ve shared is that the model you’re showing this for is adjacent to something much cooler - maybe the room adjacent has a much lower cooling set point. Or a big stretch the ground temperature is surprisingly low and you have a relatively large floor surface.
19 kBtu/ft2 is 59 kWh/m2 seems fairly realistic, but I don’t have a particularly good feel for EUI.