The laws of supply and demand apply to almost any product or service. That's true when you're trying to find strawberries in the middle of winter. It's just as true if you want to find someone to drill 500' (152 m) boreholes in an area where drillers only own drill rigs designed to drill to a depth of 300' (91 m). To build a GHX that only contractors from two states away have the equipment to build will almost always cost more to build than a GHX that can be built by local contractors.
Sometimes there may not be many options. For a project with limited land area that requires deep boreholes that can only be built with specialized equipment, there may not be much choice other than to design a system that requires drillers that can drill deep boreholes. But often there may be more cost-effective options that allows local contractors to compete for the work on a project.
An example where considering local contractor resources can make a difference in the cost of installing a GCHP system is a school project. Most school yards, unless they're located in a dense urban area, have large school yards. On many school yards there might be enough space to install a horizontal trenched or horizontally bored GHX rather than install a vertical GHX. A horizontal GHX can typically be built for about 25% to 50% less than the cost of a vertically drilled GHX, depending on the geological conditions. They can often be built at a lower cost because:
Reducing the heating and cooling loads and balancing the loads of a project...using an hourly energy model and working with the owner and design team in an integrated design process takes on an even more important role on projects where the land area required for the GHX can be reduced to the point where it's possible to consider a horizontal GHX in place of a vertical GHX. Not only is the size of the GHX reduced, but it may provide more flexibility in the configuration of the GHX.
Reducing the first cost of a GHX by taking advantage of contractor capabilities for a project makes a GCHP system more cost effective to build and improves the owners return on their investment.
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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