--- title: How Geothermal Works date: 2025-04-01T14:16:00+11:00 author: Geoff Pennington canonical_url: "https://sogeo.com.au/how-geothermal-works" section: Pages --- ![How Geothermal Heating & Cooling System]() # How Geothermal Works Geothermal heating and cooling uses the stable temperature beneath the earth to deliver low-cost, silent comfort year round. This is how it works for Melbourne homes. 01 ![How Geothermal Heating & Cooling Works in Homes | SóGeo”]() ### How geothermal heating and cooling works Geothermal heating and cooling, also known as ground source heat pumps, harnesses the consistent temperature found beneath the earth’s surface to deliver efficient, low-cost, silent comfort year round. Unlike traditional heating systems that burn fossil fuels or rely on fluctuating outdoor air temperatures, geothermal systems use the stable ground temperature (typically 16 to 18°C in most parts of Australia) to transfer heat into or out of your home, depending on the season. To understand how geothermal heating and cooling works, it helps to first understand the function of a geothermal heat pump. At its core, a geothermal heat pump transfers heat between your home and the ground through a fluid-filled loop system. This process allows the system to draw heat from the ground in winter and send heat back into the ground in summer. While conventional air conditioners also move heat, a geothermal heat pump does so using the stable temperatures found underground, making it significantly more efficient year round. This consistency in heat source or sink is what gives geothermal systems their performance advantage. SóGeo specifies inverter-driven [Stiebel WPE-I ground source heat pumps](https://sogeo.com.au/ground-source-heat-pumps) as the default for Melbourne residential installs. This is a simplified diagram showing the basic function of a geothermal heat pump. The video below shows a SóGeo installation from start to finish. 01 ![How Geothermal Heats and Cools Your Home]() ### How geothermal heats and cools your home The seasonal versatility of geothermal systems is one of their greatest strengths. By taking advantage of the earth’s stable underground temperature, these systems can efficiently heat your home in winter and cool it in summer. There is no reliance on gas or conventional air conditioners. The diagram illustrates exactly how geothermal HVAC adapts to both hot and cold seasons. It highlights the complete cycle, from how heat is drawn from the earth during colder months to how it is returned underground during the warmer ones. This simple yet powerful process is what enables geothermal systems to deliver consistent comfort and efficiency year round. The unique strength of a geothermal system is its ability to adapt seasonally, providing efficient heating in winter and cooling in summer. This is achieved by transferring heat between the ground and your home, taking advantage of the earth’s average ground temperature (around 16°C in Australia). A SóGeo ground source heat pump is engineered for 20 plus years of service, with ground loops that have a 50+ year physical lifespan and are engineered for 30 years of guaranteed thermal performance. 01 ![Geothermal System Types]() ### Choosing the right geothermal loop: horizontal, vertical, pond, or sea There are multiple ways to install a geothermal loop system, each suited to different site conditions, property sizes, and project goals. While all closed loop systems work using the same basic principle, circulating a brine solution through underground piping to exchange heat with the ground, the layout and installation method can vary significantly. Horizontal loop systems are installed in shallow trenches approximately 1.5 to 2 metres deep. This method is ideal for properties with open land where excavation is possible. It is one of the most cost-friendly options due to simpler installation requirements. Vertical loop systems are installed in deep boreholes, typically 60 to 120 metres below the surface. This option is best for smaller properties or areas where surface space is limited or cooling loads are high. It is also well suited to sites with rocky or dense soils where horizontal installation would be difficult. SóGeo’s sister company GT Drilling handles [compact-rig vertical drilling on sites where conventional access is not possible](https://sogeo.com.au/geothermal-drilling-options-for-tight-melbourne-sites). Pond and sea loop systems involve submerging the closed-loop piping in a body of water such as a pond, lake, or the sea. These systems benefit from stable water temperatures and can be highly efficient and cost-friendly where a suitable water source is available. SóGeo delivered a lake-source geothermal install at a private property in Main Ridge, drawing heat from the lake during winter and rejecting it back during summer. These system types all offer the same year-round energy efficiency and reliability, but the best option depends on your property’s landscape, geology, and energy needs. At SóGeo, we assess your site conditions and project goals to determine the most suitable and efficient loop design. Our in-house drilling team handles vertical loop installation, and we coordinate horizontal and pond loop installs with the right civil partners. [Get in touch with our team of experts.](https://sogeo.com.au/contact-us) ## Frequently asked questions about geothermal heating & cooling ### What is geothermal heating? ➕ Geothermal heating is a method of warming and cooling a building using the stable underground temperature of the earth. A ground source heat pump moves heat between a fluid-filled loop buried in the ground and the building’s hydronic distribution system, which can be underfloor heating, panel radiators, or fan coils. The system delivers heating in winter and cooling in summer, and runs on electricity at a coefficient of performance of four to five. ### How efficient is a geothermal heat pump compared to gas or air source? ➕ A geothermal heat pump runs at a coefficient of performance (COP) of 5 to 7. Every kilowatt-hour of electricity delivered to the heat pump produces 5 to 7 kilowatt-hours of usable heat. This is higher than an air source heat pump (COP 3.5 to 4) and far higher than a gas boiler. In a Melbourne home, geothermal typically uses 50 to 70 percent less primary energy than gas, and 25 to 40 percent less electricity than air source for the same heating output. ### How long does a geothermal system last? ➕ A correctly designed geothermal system is engineered for very long service life. The heat pump itself runs 20 to 25 years with annual maintenance. The ground loop, the buried portion, is designed for 50+ years and frequently lasts longer because it has no moving parts and is protected from the elements. The internal hydronic pipework typically outlives the equipment. ### Can geothermal be installed on a tight Melbourne site? ➕ Yes. Compact-rig vertical drilling allows ground loops to be installed in inner-Melbourne sites where conventional drilling would not fit. SóGeo’s sister company GT Drilling specialises in these installs. See our geothermal drilling options page for the technical detail on minimum access widths and borefield layouts for constrained sites. ### Can a SóGeo geothermal system heat a pool, spa, or cold plunge? ➕ Yes. A geothermal system is a single source of heating and cooling capacity that can serve multiple loads from one heat pump. Common configurations include hydronic space heating, hot water for showers and taps, pool heating in shoulder months, spa heating year round, and cold plunge cooling in summer. Adding a pool, spa, or plunge load typically adds a separate plate heat exchanger and circulation loop tied to the same ground array. SóGeo sizes the borefield to handle the combined annual load profile so every function performs reliably across the 50 year design life of the ground loop. ### Does geothermal reduce my home's connected load and max demand? ➕ Yes, and significantly. A geothermal heat pump draws less electrical current per kilowatt of heating output than an air source heat pump because the ground loop delivers a more favourable source temperature year round. A SóGeo geothermal install for a typical Melbourne home draws roughly 2 to 3 kW at peak heating demand, compared with 5 to 7 kW for an equivalent air source system delivering the same heat output. The practical result: many older Melbourne homes can run geothermal on their existing single phase electrical service without needing a switchboard upgrade or a new three phase connection, which saves around $3,000 to $8,000 on electrical works alone. This is one of the most underrated commercial advantages of geothermal and a frequent reason architects specify it on heritage retrofits with constrained electrical service. ## Our Partners [ ![Reece](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/Reece.png) ](https://www.reece.com.au/) [ ![Stiebel Eltron](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/Stiebel-Eltron.png) ](https://www.stiebel-eltron.com.au/) [ ![Mitsubishi](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/Mitsubishi.png) ](https://www.mitsubishielectric.com.au/) [ ![Purmo](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/Purmo.png) ](https://www.purmo.com/au) [ ![Viessmann](https://sogeo.com.au/uploads/suppliers/_AUTOx96_crop_center-center_none_ns/viessmann_wordmark_rgb_1_vitorange.png) ](https://www.viessmann.com.au/)