It appears that SERI had a good deal of influence in the 80’s in the Denver area. I say this because I purchased a solar hot water system from a couple in Centennial who bought a foreclosure that has a huge trombe wall and three huge bins of rock storage in the basement! I was SOOO impressed. Unfortunately he said the system has been abandoned for years and even some of the vents were tiled over etc. They tried the fans which still work but they blasted dust into the air.
This was the rock storage bin idea.
I was so excited, told him it was essentially free heat forever if they could just resurrect the system. So much expense into developing it and just sitting there doing nothing. The lower vents were blocked off with styrofoam panels. There were three stories of aluminum sliding glass doors in front of a concrete block wall. The brick for the inside wall was solid and all soldier course. The house was huge–2220 sq. ft on the first floor alone, then an upper story and the walk out basement rooms. At one time all heated with solar.
There is so much ignorance about these systems that it is sad–maybe tragic. The former owners who blocked off a system that would have given them free heat, the roofers who cut the solar panels and crushed the pipes going into the panels so that they will have to be disassembled to be fixed, the lack of contractors who would know how to return the house to its former glory, so they have a great house despite its solar “quirks” instead of because of them.
I wish I had taken some photos. The front of the house was indistinguishable from its neighbors, the back was gorgeous at three solar stories high with a sunroom on one side and a trombe wall on the other and it looked out on a lovely little green space before the next neighborhood. I wish they could renovate the system, but the expense would probably be beyond them as a younger couple with two little kids.
Current theory is that rock storage did not “work” as well as superinsulation does–just keeping the heat in the house is better. But if you HAVE rock storage, it depends on what you want to get out of it to determine its worth. Like a heat pump, it will only use the ambient temp of the rocks to pre-heat the house–likely it won’t actually heat the house adequately during the coldest weather due to the inefficiencies of air to rock heat transfer. Also there would be the thermal swing–if you actually store lots of heat–how long would it take to cool off when the temps get warmer? Yet my research shows this type of system is still being researched and in some cases installed–especially outside the US.
I thought it was so neat and if it were not so far away I would love to explore the system and see what the issues are. But I have my own systems to attend to, including a new hot water solar system that I purchased from these folks that needs to be restored.