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.
Kermit the Frog always said it was so hard to be green...he was wrong! Ground source heat pumps can make your home NetZero without doing much to the home. When combined with other renewable technologies such as wind, solar, building a more energy efficient building and selecting efficient appliances, it's not even that hard to get off the grid completely...
Every once in a while a developer comes up with software that makes life a lot easier! Ground Loop Design (GLD) has just done that for the commercial ground source heat pump industry. Let me explain:
Too often I've seen a set of tender documents put out to bid with an area blocked off on the site plan that says "drilling contractor shall provide GHX that has a capacity of 720 MBH and will be responsible for performance of the GHX." That's kind of like going to your doctor with chest pains and he says "go see the fellow in the nice suit...he's from the drug company. He'll sell you the medication you need"
Thank your to each of you who took the time to respond to my survey about design training. Your responses confirmed some of my suspicions about why designers are not taking the time to learn what's different about designing a ground coupled heat pump system compared to designing a conventional HVAC system.
Some of the highlights:
If you're interested in some custom course options, follow this link.
I'd appreciate your feedback about design courses and workshops by responding to the following survey. Thank you.
Commercial geothermal system design course survey
A building with a well designed GCHP system uses about 60% to 70% less energy for heating, cooling and domestic hot water than the same building built with a conventional fossil fuel heating system and a conventional air cooled chiller. If the system integrates other renewable technologies and thermal energy storage, energy use can be reduced even more. With concerns about climate change (whether it's real or not), more building owners and developers are making changes to the way their buildings are designed.
The first thought many have when considering the payback of a GCHP system is: "how much extra the system will cost compared to a conventional HVAC system" divided by "how much the system will save in energy costs". But there are often other things that should be considered when thinking about the payback of a system.
Getting drill rigs and excavation equipment onto a large schoolyard to install a GHX is usually easy to do. There's ample space to store materials on the site, space for site construction trailers and areas dirt from excavations can be piled. As larger GCHP projects are built on smaller sites, getting heavy equipment onto the site becomes much more challenging and expensive.
In over 3 decades working in this industry I've had two clients who have not been directly concerned about the return on the investment needed to install a GCHP system. One was an association of roofing contractors...they were mostly concerned about installing equipment on the roof of their new building than the cost of the GHX. The other was an association of rural municipalities who simply wanted to make a statement about "how green they were". Virtually everyone considering a GCHP system asks two questions:
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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