5 Ways That Geothermal Can Go Wrong, and How to Do It Right
I’m Bryan Roberts — Sr. Energy Consultant. I joined Dandelion Geothermal as one of the first employees and have worked in clean energy and environmental planning for over a decade. Every year, my colleagues and I meet thousands of homeowners who are interested to learn more about Dandelion and our geothermal heating and cooling technology. The people we meet have varied degrees of understanding around how geothermal works. Some of them have even heard that geothermal is great in theory but just doesn’t work well in cold climates.
I can list example after example of geothermal (“geo”) success stories. That said, it’s equally important I detail the reasons why some geo installations go wrong and how our approach at Dandelion ensures we avoid those pitfalls.
Geothermal System Design
For decades, common practice around the design and installation of conventional, fuel-burning heating systems has been to determine what a building likely needs and then oversize it. The guiding principle of that approach is, essentially, too much is better than too little. And, while that approach may keep you warm, it’s also expensive, wasteful and unsustainable.
Geothermal systems work differently and must be engineered precisely to sit squarely in the Goldilocks Zone of “just right” to ensure efficient operation, a very comfortable conditioned environment, and a respectable 20-25 year life-span for the heat pump.
To get it “just right,” we spend hours collecting and assessing data about the home. Some of the key details about the home we must consider include the total square footage, insulation R-values, the types and number of windows and doors, building construction materials, ceiling heights, and the list goes on….
Assessing these details is what enables us to determine the thermal exchange rate between the conditioned space indoors and the unconditioned space outdoors — we call the results of this assessment “heating and cooling load calculations.” With accurate data collection and calculations, we can size the geo system’s heat pump and ground loop with precision to ensure the system effectively and efficiently keeps up with the demand for a comfortable environment inside your home.
Sizing and Designing Ductwork for Geothermal
Dandelion geo systems rely on forced-air distribution for heating and cooling, and therefore require ductwork to push conditioned air from the heat pump into each room of the home. The quality of the ductwork and its ability to support the airflow requirements of the geo system are important considerations. Primary reasons that the geo system may inadequately distribute conditioned air throughout the home include ductwork that is undersized or oversized; too few supply or return branches and vents; ductwork that is poorly insulated and/or leaky at the seams; airflow constriction due to poor routing paths or dust and debris in the ductwork, or filters that are clogged and need to be changed. Calculating the required airflow to each room is part of the design process, and making sure the ductwork can support that airflow initially and ongoing is essential to proper system performance.
Considering Local Climate
The climate of any given region varies due to changes in latitude and a range of geographic features, and these climate variations must be considered when matching a geo system to the local environment. The International Code Council has developed the International Energy Conservation Code Climate Zone Map which characterizes each County throughout the United States by a distinct set of “climate zone” characteristics such as temperature and precipitation extremes and norms. A clear sense of the temperature extremes the geo system must be designed to accommodate is vital to proper system function and efficiency. As a baseline, the Dandelion team references climate zone characteristics as well as data from regional weather collection centers during the design process.
System Control Malfunctions
Although geo heating and cooling relies on somewhat fundamental scientific principles and mechanics, a set of reasonably complex mechanical and electrical devices and software controls are in play to operate and adjust the system. If the control mechanisms are faltering or fall out of adjustment, the geo system has potential to operate at subpar levels and even shut down altogether. Once identified, control issues can typically be addressed quickly and the geo system left to resume proper function. To sweeten the pot, Dandelion geo systems include monitoring sensors that send our technicians performance stats every few seconds and can help to reduce down-time by setting off dashboard alerts when a system component or control requires service.
Finding the right installer is essential to a geothermal system that works as expected and promised.
How Dandelion Gets Geothermal Right
At Dandelion, we ensure that we get the data points and design right with a team of skilled individuals who are well trained and fully committed to geothermal heating and cooling systems and only geothermal heating and cooling systems. We do this with a well-defined — albeit continuously evolving — process for data collection and analysis, system design, installation and maintenance.
Dandelion provides a warranty on equipment, labor and workmanship, plus we monitor system performance. If a Dandelion geothermal system is not working properly, not only are we alerted to that fact via our monitoring devices, but we are obliged to address the issues in accordance with the terms of our warranty.
Perhaps most importantly, Dandelion’s mission is to make geothermal available and affordable for everyone. Given that we plan to be around long enough to accomplish the full potential of our mission, we have no choice but to prove to our customers — past, present, future — that our assurances and results are one and the same.