In fact, the whole idea of this system is to keep the ground around it frozen. An air craft hangar in Anadyr, Russia, was built on permanently frozen ground. Typically, an expensive, insulated foundation would be built to prevent heat from the building to move into the ground it is built on from melting the permafrost. For this project, pipe was simply laid on the permafrost, covered with about 1' (300 mm) of sand and gravel and 6" (150 mm) of high-density extruded foam insulation. A conventional concrete slab was poured on top of the insulation with radiant floor heat pipe.
Chilled fluid is circulated from a water to water heat pump through piping under the floor to extract enough heat to maintain the temperature at approximately 20-25 F (-7 to -4 C). Heat removed from the permafrost is used to provide some of the space heating and domestic hot water for the facility.
Melting permafrost under a building creates an unstable foundation for the building. A heated building built directly on the permafrost gradually transfers enough heat to the ground to melt the permafrost. To prevent heat transfer, specially insulated piles are used to isolate the heated building from the permafrost. The GCHP system was much less costly than building insulated piles to prevent heat from being transferred from the building to the permafrost. And it has a side benefit...heat recovered from the frozen ground provides some of the heating for the building, reducing the need for oil in the facility.
In my blog I'll be expressing my opinions about what I've the learned about ground coupled heat pump (GCHP) systems over the last 30 years. I've been very fortunate to work with many interesting people who are passionate about this technology...engineers, geologists, mechanical contractors, drillers, excavation contractors...in different parts of the world. I've learned a lot from them and will be using this forum to pass on some of the things I've learned and feel are important. Please feel free to use this information if you feel it's worthwhile...hopefully you can avoid some of the same mistakes I've learned from.
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