Geothermal heat pumps

GSHP systems can / should be a much bigger part of the HVAC market

Electrifying buildings is becoming a bigger deal with many building owners, electric utilities and politicians starting to realize there just might be something to climate change. Cities are limiting expansion of the natural gas infrastructure and gas utilities are starting to install geothermal piping systems instead of gas lines. 

So why are engineering firms so hesitant to design GSHP systems? In fact, in many instances, actively discouraging their clients from installing them...citing examples of systems that dont work, or systems that were so expensive to build there was never a decent return on investment.

Part of the problem is that there is a fundamental difference in the design of a GSHP system compared to a conventional HVAC system.  Designing a GSHP system means the designer has to design the energy source and heat sink...the ground heat exchanger. It's not simply specifying the size of a gas pipeline from a gas supplier's table or a cooling tower from a manufacturer's website. 

It requires knowing not only the peak heating and cooling loads, but the annual heating and cooling energy loads as well. That requires an accurate hourly energy model...and to optimize the system there should be several iterations of the energy model to see the impact of different glass, lighting, ventilation strategy, equipment efficiency, etc. to try and balance energy transfer to and from the ground. 

Otter Tail Power is an electric utility in MN that helps the design community in MN to learn a design methodology to optimize GSHP systems. Download this article that describes their Design Assistance Program.