Geothermal technology is designed to harness the earth’s energy, which is both renewable and clean. Among its many uses, geothermal energy can be used to heat and cool commercial buildings. The highly efficient systems that make this possible are geothermal heat pumps.
Geothermal heat pump (GHP) systems, also called earth-coupled or ground-source heat pumps, use a series of underground, liquid-filled pipes that exchange heat with their subterranean surroundings to keep buildings comfortable year-round. While air temperatures tend to vary as seasons change, geothermal energy keeps ground temperatures relatively consistent, providing a heat source when it’s cold outside and a heat sink that enables cooling when weather is hot.
By using sustainable, free geothermal energy, GHPs reduce a building’s energy consumption by up to 25% and can cut its emissions from energy use by up to 50%. With such extraordinary benefits, it’s puzzling why these incredibly efficient and sustainable HVAC systems are not yet widely used.
A Naturally Sustainable Design
Geothermal energy in HVAC dates to 1912, when Mexican-Swiss engineer Heinrich Zoelly patented the geothermal heat pump, but these systems weren’t fully commercialized until the 1970s.
Today’s GHPs are like traditional water source heat pumps, except they use a ground heat exchanger instead of a boiler and cooling tower water loop. A ground heat exchanger consists of high-density polyethylene (HDPE) pipes buried under the frost line. As water circulates through the pipes, it either pulls heat from or brings heat to a building. Traditional air-source HVAC systems collect and remove heat using the outside air, which is comparably inefficient during peak summer and winter conditions.
There are several different GHP system configurations available:
- Open loop systems utilize water from a well, lake, or stream as a heat source or heat sink.
- Closed ground loop systems utilize a water and antifreeze solution through a piping loop buried underground.
- Pond/lake loop systems are a form of closed ground loop systems that use a heat exchanger submerged in a drought-resistant body of water.
Loop temperatures, local geological conditions, installation costs, as well as codes and regulations can help building owners determine which system can or should be used.
Unlocking the Benefits for Commercial Applications
As they account for most of a building’s energy costs, heating and cooling are primary concerns for building owners. Many building owners face high energy bills, and those located in areas banning the installation of natural gas equipment in new buildings are having to find new ways of keeping tenants comfortable. As utility prices rise and municipalities distance themselves from fossil fuels, it’s advantageous for building owners to use GHP systems that alleviate costs and environmental impact.
Even though their function is similar, GHPs are substantially more efficient than traditional air or water source heat pumps. Compared to air source heat pumps, GHPs can reduce energy consumption by 25% to 50% and, in the coldest temperatures, may achieve energy efficiencies that reach 300% to 600%. Because of the amount of free energy they absorb, GHPs only need a small amount of purchased electricity to run. GHPs only require 1 kilowatt-hour (kWh) of electricity from the grid to produce 12,000 British thermal units (BTUs) of heating and cooling. In contrast, a standard air source heat pump uses 2.2 kWh to produce the same amount on a day with 95⸰F air temperature. Three to four kWh of free energy combined with one kWh of grid energy yields four to six kWh, resulting in building efficiencies that are three to four times higher than required to run the system.
GHPs are also twice as efficient as the top-rated air-source air conditioners and almost 50% more efficient than the best gas furnaces; they have the lowest emissions levels of all applications in HVAC. GHP systems reduce the carbon emissions that result from the energy a building uses by up to 50% and release practically no emissions on-site. Cutting energy bills and lowering a building’s carbon footprint even further, GHPs can also be used to heat the building’s standard water supply. With residential and commercial buildings accounting for nearly 40% of global greenhouse gas emissions, increasing the use of GHPs would substantially reduce global emissions for a healthier, cleaner planet.
The savings that GHPs provide don’t end there. Commercial buildings that use geothermal systems may be eligible for many incentives, including federal tax credits and energy rebates. With no cap, the federal tax credit for commercial applications is equal to 10% of the total system cost, with the option for a five-year Modified Accelerated Cost Recovery (MACR) system depreciation or 100% first year depreciation on a total system and cost basis. Building owners can also apply for incentives from utility and energy companies. These rebates are for customers who implement energy efficiency projects and can be substantial if buildings use GHPs to deliver savings.
While energy efficiency and a smaller carbon footprint are beneficial enough, GHP systems also offer long component life. The heat exchanger and overall underground infrastructure can run for 25 to 50 years, while heat pumps can last more than 20 years. The factor that often keeps building owners from installing GHP systems is the upfront capital cost, yet this long service life paired with energy savings is often enough for GHPs to pay for themselves within five to 14 years.
The Growing GHP Market
Although geothermal energy has not enjoyed the public awareness that other renewable energy sources have garnered, the demand for it is growing. The number of GHPs installed in the United States grows every year, and the market for systems is expected to exceed $2 billion by 2024 in the U.S. alone.
There are three main factors driving this demand. First, builders and developers want to obtain Leadership in Energy and Environmental Design (LEED) credits, as well as reduce energy costs. Second, states committed to achieving climate goals, such as California, New York and Vermont, have implemented stringent energy codes and encourage residents to use air-source and water-source heat pumps. Third, geothermal technology is being adopted in large-scale installations; the U.S. military will use it in new construction and in upgrades for existing facilities.
While contractors who are already providing these systems will be at an advantage, there’s still time for those who aren’t to get on board. As the popularity of GHPs grows, so will business opportunities. Contractors who include geothermal heat pumps in their offerings will enjoy first-mover advantage, communicate their commitment to sustainability, and have the chance to pass on significant energy savings to their customers.
Opening the Door to Decarbonized Comfort
As regulations and trends move the HVAC industry toward decarbonization, geothermal heat pumps are increasingly being seen as a compelling, high-efficiency heating and cooling solution. Their energy- and cost-saving benefits have captured the attention of a wide variety of commercial customers who will no doubt be looking to install these lasting systems. With unparalleled energy efficiencies, minimal environmental impact, extensive service life and flexibility, GHPs are practical options for sustainable comfort now and in the future.