Cargo containers are by 2019 frequently being used for housing or as building materials in housing structures. What if we take that one step further?

Instead of horizontal, think vertical. I'm staring at a building, made of brick, that is a square. Four square walls. There are 100,000 bricks (say $1 a piece) in each of the walls. That's $100,000 per wall just for parts.

What if instead you dropped 40' cargo containers a foot below ground, upright. Instead of little bricks use the equivalent of giant steel lego blocks. This way it's $8000 a wall not $100,000. Interior space owld be reduced, these are very thick walls, but the air gap insulation would be superb and they'd provide cold storage in winter by doing noting more, but circulating that air from the ground the benefits of building envelopes would apply. This might work well for industrial buildings, especially where HVAC costs are high in winter or summer.

For housing, drop 40' containers 20' down. Build a floor halfway up and have two large spaces, one below and one above ground. This would not impage the cost of finishing out the building it would be better than brick at a tenth the cost.