Underground housing, underground businesses, etc. Would that be better for the environment + possibly save on energy costs? Also possibly safer in certain scenarios like tornadoes etc.
Potential issues that immediately come to mind are ventilation, earthquakes, and flooding. But it’s not like underground dwellings/basements/etc. aren’t a thing, so maybe those issues have been addressed in ways I’m not familiar with.
Easier to build the house and cover it with soil and vegetation instead of digging down. The front door and windows can face south to take advantage of passive solar heating in the winter.
I think one of the best uses of “underground” is to run piping in a large circuit around the property. I read in a passive solar book that 4 feet underground it’s about 4C on average world-wide.
Summer: Warm air goes in from the living space, travels along a couple hundred feet of pipe, cool air comes back into the house. I’m not sure if the air would be 4C but should save a lot of electricity.
Winter: Same system but the air pumped into the house should be much warmer than what’s above ground. Usually, the coldest days are sunny so passive solar designs can warm a house to a comfortable level.
Better option is to run a heat pump into that underground loop. You really don’t want underground air getting into your house, and a heat pump will let you cool or warm the air using that same underground loop.
I was thinking of a closed loop system not pumping moldy humid air into a house.
Your idea isn’t bad but does need a space big enough for a technician to service the external unit. Also, the external part of a heat pump isn’t supposed to be enclosed. Not sure if a tunnel counts as enclosed or not.
Ground loop heat pumps are already a thing.
As for maintaining the unit, you just have a service panel you can remove to access it.
Always good to learn something new, thanks.