Tents have "flies" ... a flap over the tent to keep out rain water while the tent itself is permeable to allow water vapor to leave through the fabric of the tent.
What might be gained by applying the same principle to sunshine on a hot roof in the summer? ... Either permanent or retractable.
Now about them worms ...
Here in Texas, the average summer temperature is 86 degrees (that includes the nighttime temperature). In the winter the average is maybe 40. So the temperature below ground is about midway, say, 63 degrees. What is needed is to send the heat down in the summer and bring the cool up ... vice versa in the winter. This is done but not (to my knowledge) cheaply enough to be widely used in a residential setting.
I'd like to try the garden hose method.
As a youngster, I sent the garden hose down to God knows where using water pressure. The hose just goes down like a snake and you can't get it back. It will take your entire garden hose if you let it. I "cut" my losses at about ten feet.
I propose to cut through whatever is down there with high pressure water ... the type of pressure that can cut through 5 inch plate steel ... just whatever amount is necessary. Drag the pipe down with the "steerable drill head" and by means of computer signals, run the pipe in a coil at great depth (200 feet?) ... then to the surface. Then hose out the wet slurry inside the pipe with a smaller "cleaner hose".
I have seen (on the web) snakelike propulsion mechanisms. NASA is interested in the possibilities of "snaking" along the ground on other planets where the terrain makes wheeled vehicles impractical. You need three length-adjustable rods at each segment of the snake to control attitude. Here you would just neeed to attach a "water drill" to the business end and pull a tube into and through the wet slurry behind it ... then flush out the tube.
It's got to be cheap though or forget it. But think how much you could save on AC if you could pump water through your warm house in the summer and down to the depths to get cool. You might use your regular AC just to supplement. You only need a pump and that's a small energy requirement since as much water is going down as is coming up.