Btw, how about growing citrus in Nebraska? With no HVAC?

Yup.

https://www.youtube.com/watch?v=ZD_3_gsgsnk

Simplifying, that is a semi-underground greenhouse (the Native American word for it is "Wallipini") which faces the sun, uses thermal mass, etc., and duct work underground below the frost line, with a push fan and a pull fan. Like the push and pull fans on a tower PC.

Not to make it sound like I am diminishing this man's work. Quite the contrary, I am super impressed with him and what he has achieved here.

Btw, how about growing citrus in Nebraska? With no HVAC?

Yup.

https://www.youtube.com/watch?v=ZD_3_gsgsnk

Simplifying, that is is a semi-underground greenhouse (the Native American word for it is "Wallipini") which faces the sun, uses thermal mass, etc., and duct work underground below the frost line, with a push fan and a pull fan. Like the push and pull fans on a tower PC.

Not to make it sound like I am diminishing this man's work. Quite the contrary, I am super impressed with him and what he has achieved here.