From the roadway, this home simply looks like a grass covered hill, with a few odd-looking concrete structures scattered about. But inside, it’s an architectural marvel designed for the utmost in energy efficiency and luxury living. There’s only one right angle throughout the entire 4200 square feet of living space. That’s located in a closet so visitors will never see it. Homeowner Bill Coleman says you’ll find no insulation behind the interior walls of this home. There’s no need. Most of the walls and roof are buried under an earthen berm that’s at least 4' thick, giving those areas of the home an energy efficiency rating of R-100. The only exposed wall is in the front of the house, and it contains mostly double-pane energy efficient windows. The only exposed portion of the roof looks like a submarine coming to surface, surrounded with glass blocks to allow in light.

Michael Holigan: Bill, this is the only exposed section of your roof. This is where your light is getting in?

Bill Coleman: Right, it comes down the center of the house. Also, some windows on the front side of the house.

MH: It goes through that glass block, and it’s just a shaft running down there?

BC: The walls of the shaft are white so the light reflects and spreads throughout the center.

MH: I know it’s a big home so we’ve got to be standing on the rest of the roof right now and how deep is the soil right here?

BC: The dirt itself is more than 4' feet deep. Then we’ve got polyurethane insulation mats underneath that.

MH: How do you keep it all draining because I know you don’t want any water leaks. How do you get the water out of here?

BC: There’s a very slight slope to the south that directs all of the water off the roof.

MH: The material I see you’ve got a little bit of old asphalt it looks like. Is that down on the roof also?

BC: Yes, all of the fill dirt for covering the building was provided free by the city of Dallas.

MH: How heavy is this now? You’ve got a lot of soil and a lot of fill on top of your roof.

BC: I come up with a figure of around 800 tons overhead.

MH: Do you ever worry about earthquakes?

BC: No, not earthquakes or tornadoes for that matter, but when it creaks we listen very closely.

MH: Makes you a little nervous?

BC: Just a little.

MH: Right over here... what’s at this edge?

BC: We’ve got a porch that runs the length of this side of the building on this side of the house.

MH: We’re 20' deeper now underneath the ground. That sure is a lot of light, Bill. What do you call this?

BC: It’s a clerestory window and that allows the light to come in from the east and west and bounce off of the walls above us.

MH: That’s just hose glass blocks that we just saw. I notice over here you’ve got quite a beam. It looks like it’s holding up the whole ceiling structure I don’t see any walls supporting that at all.

BC: The beam that runs the length of the house provides an edge for the planks above us to rest on. Each one of these planks weighs about 4,000 pounds, plus what you’ve got on the dirt above that.

MH: These planks are concrete?

BC: Yes, they’re pre-stressed concrete all laid in place in a matter of a few hours.

MH: You’re holding up a lot of dirt. How many pounds?

BC: 800 tons is what I estimate; it's based upon the weight of the roof and the dirt on top of it.

MH: Just this one side has windows. Sort of like a walkout basement?

BC: Yes, we’ve got windows and doors on this wall, which is the west facing wall. This allows us to meet all the building codes and requirements about emergency egress.

MH: Okay, for egress so in case there’s a fire in here you have to have a way out. All the bedrooms are built against the wall with windows?

BC: Yes, and they also have a view that way. Out the backside of the house.

MH: Then the rest of the house, all three sides, no windows?

BC: It’s all concrete walls with no openings and dirt on the outside.

MH: Low utility bills?

BC: Very, very low. We spent over $250 for a house half this size before we moved into this one.

MH: Each month on utilities? How about this one?

BC: Less than $200 a month for 4200 square feet.

MH: Twice as big as the other one.

BC: Yes.

MH: Tell me about this. This looks like a New Mexico fireplace if I’ve ever seen one.

BC: It was designed and built by a very nice lady from Taos, New Mexico. She builds fireplaces like this all around the world.

MH: Opening there and an opening on this side as well?

BC: Right, it warms both sides of the room. The rear of the fireplace is like a parabolic mirror. It’s set up in such a way that it reflects the heat outward from the fire logs as they’re burning and this warms a much larger area of the home.

Because there are no load bearing walls. A future owner could completely tear out the home’s existing walls and re-design the floor plan. Also, there’s no attic to run the air conditioning and electrical lines.

MH: Bill, it looks like you have to figure out some creative places to put stuff that would ordinarily go in the attic or underneath the slab?

BC: We’ve got the air conditioning ducts and all of the water, both cold and hot, traveling through a chase to the bathrooms and to the kitchen throughout the whole house.

MH: Where do you end up putting the blower unit for your air conditioner?

BC: It’s in the tunnel here that connects the house to the garage. We’re making sufficient use of all the space.

MH: There’s the unit up there?

BC: The blower for the heater and the air conditioner is mounted up above there.

MH: How about the water heater?

BC: We’ve got a water heater out in the garage. Through that insulated pipe you saw in the chase it delivers the hot water throughout the house. We’ve got a continuous running electrical pump, so that we expand the capacity of the hot water heater by the pipeline delivering to all of the faucets.

Living underground certainly has its advantages when it comes to energy efficiency. Plus, Bill saves $1000 dollars a year on insurance because the home qualifies as a semi-fire resistant structure. But take in mind this was a long, and somewhat costly construction process. It took 18 months to build this home at a cost of more than $200 per square foot.