We are building a house with a passive underground climate control system. There are actually many different ways of doing this, all with their own unique features. Our system is pretty simple. We dug down three feet into the ground. Our stem wall extends two feet above the ground. This area was filled with 24 inches (290 tons!) of smooth river rock. We built vents in the stem wall on all sides of the house to allow fresh air into this space. The air is cooled under the house and pulled up through floor vents as the hot air is pulled out through exhaust vents in the ceiling. As I said, there are many variations to a system like this depending on your homesite, climate, materials available and so on. Operating our system will take a little trial and error, but should be pretty easy. It basically comes down to opening and closing vents to adjust the temperature in the house. Anyway, the rocks got here a few weeks ago thanks to the guys from Cemex. The rocks we got are a byproduct from the production of cement. A cement plant is basically a mining operation. As they screen material they are left with rocks about the size of a tennis ball to a small football. The cement company has no use for these rocks and they just pile up. These rocks are perfect because of the small air spaces they create together. I expect the majority of our cooling to come from our passive system, however we are building a home in a very hot climate and it is likely that we will need air conditioning for some additional cooling. We will see how the passive system works and go from there.
The rock arrived via dump truck. 300 tons total, 19 loads.
A gargantuan loader with a skilled operator.