...Only that it does! One of the factors that drives the cost of a GHX is what kind of equipment and methods the engineer specifies contractors in the area are prepared to work with. Design software considers the placement of the pipe in relation to the earth's surface, other pipes, thermal properties of the soil, etc. It does not consider how the pipe was placed there. Simply put, it doesn't matter how the pipe was placed where it is...it only matters that it gets into the ground where it is needed in the most cost-effective manner possible.
The cost of getting the pipe in the ground often makes or breaks a project...the return on investment is often the deciding factor in a project being built with a GCHP system or a conventional system. Working with local excavation and drilling contractors and exploring options they can suggest, based on the type of equipment they have access to, can often result in a more cost-effective solution than you may be familiar with.
Considering different GHX options can also make a project less costly to build. For some projects there may be some significant earth work to level playing fields, create parking lots, create landscape features. There's no reason some pipe can't be simply laid on the ground and let the earth movers loose to pile dirt on top of it. There's also no reason to not consider horizontal GHX options. There are many methods of getting pipe in the ground horizontally...trenches, large earth moving equipment, horizontal drilling equipment, etc... it really doesn't matter how it gets there...as long as it does.
Another option to consider in cooling dominant projects is to dissipate heat during the winter to melt snow on parking ramps and loading dock areas. Think about these areas as very shallow horizontal GHX's. If they are properly controlled it's possible to use these areas to control and moderate the temperature of a vertical GHX. The point is, there are often a lot of options if we take the time to look for them and consider them.
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.