--- title: "Geothermal Heating and Cooling Systems in Australia: The 2026 Guide" date: 2026-09-06T10:30:00+10:00 author: Darren Burch canonical_url: "https://sogeo.com.au/blog/geothermal-heating-and-cooling-systems-australia-guide" section: Pages --- ![DSC 0259]() # Geothermal Heating and Cooling Systems in Australia: The 2026 Guide A geothermal heating and cooling system is a ground source heat pump system: a buried loop, a water-to-water heat pump, and hydronic distribution, delivering heating, cooling and hot water at a COP of 5 to 7 all year. This guide covers what a complete system includes, loop options for Australian sites, honest costs and downsides, and what real Melbourne systems measure. **Short version first.** A geothermal heating and cooling system in Australia is a ground source heat pump system: pipework buried in the ground or laid in a lake, a water-to-water heat pump, and underfloor pipework, radiators or fan coils to deliver the result. One plant room provides heating, cooling and hot water at a coefficient of performance of 5 to 7 all year, because the ground a few metres down holds a steady temperature no matter what the weather is doing. It has nothing to do with volcanic steam. This guide covers what a complete system includes, the loop options for Australian sites, what it costs, the honest downsides, and what real Melbourne systems measure. ## What a complete geothermal system includes Four parts make up a residential geothermal system, and the design of each one decides how well the whole thing performs. - **The ground loop.** Sealed high-density polyethylene pipe buried in trenches, drilled boreholes or laid in a lake, circulating fluid that picks up heat from the ground in winter and rejects heat into it in summer. Buried loops last 50 or more years, and we size them on a 30-year thermal design horizon so the ground temperature the heat pump sees stays within its limits for decades. - **The heat pump.** A water-to-water unit in a plant room or garage, with no outdoor fan unit. We install the Stiebel Eltron WPE geothermal range and are its exclusive Victorian distributor and installer. Inverter compressors modulate to the load rather than cycling. - **The distribution.** Hydronic underfloor heating, radiators or fan coils. Underfloor runs at the lowest water temperatures and returns the highest efficiency; radiators and fan coils suit retrofits and rooms that need fast response, and fan coils also deliver cooling. - **Hot water and heat recovery.** The same heat pump makes domestic hot water through a stainless steel cylinder, and in summer a de-superheater captures the heat pulled out of the house during cooling and puts it into the hot water, or into a pool or spa, for free. If you want the physics of how the heat pump moves heat, our [how geothermal works](/how-geothermal-works) page and the [geothermal basics guide](/blog/understanding-geothermal-heating-cooling) cover it. This article is about choosing and specifying a system. 01 ![DSC 0410]() ### Ground loop options for Australian sites The loop is the part of the system you never see again, so it is the part we design most carefully. **Horizontal trenches** suit properties with open ground: pipe laid in wide trenches at close spacing, then backfilled and landscaped over. It is the most economical loop where the land allows, and it is how most of our regional and semi-rural projects are built. **Vertical boreholes** suit tight Melbourne blocks, heritage sites and homes where the garden has to stay intact. A compact rig drills bores in a courtyard or driveway and the loop disappears underground; our [drilling guide](/geothermal-drilling-options-for-tight-melbourne-sites) covers rig access and site fit, and our Kooyong heritage project is the worked example. **Lake and dam loops** use a body of water as the heat source. On our Main Ridge project the lake held an 8°C winter source temperature and the system returned a SCOP of 5.1 with no drilling at all. Every option is sized from the heat-loss calculation and the ground conditions, and an undersized loop is the one mistake you cannot fix later, which is why we design to a 30-year horizon rather than the first winter. 01 ![Pump room]() ### What real geothermal systems measure Efficiency claims are cheap. These are the seasonal figures our own installed systems returned. The seasonal coefficient of performance, the SCOP, is the number that shows up on the bill: heat delivered across the whole year divided by electricity used. Our measured projects came in at 8.1 at Coimadai, 7.4 at Invermay, 5.2 at Port Campbell and 5.1 on the Main Ridge lake loop. Port Campbell also cut the home’s power consumption by 70% on a single-phase supply. The [case studies](/case-studies) carry the detail on each. The reason geothermal holds these numbers is that the ground does not have weather. An air source heat pump loses efficiency on the coldest mornings and the hottest afternoons, when a cooling COP can fall to 2 or 2.5 in a 35°C heatwave; a ground source system stays at 5 to 7 in both. At winter design conditions air source also draws roughly 40% more power for the same heat, which matters on a tight electrical supply, as our [maximum demand guide](/blog/geothermal-heat-pumps-in-melbourne-sydney-reduce-connected-load-and-save-on-electrical-upgrades) explains. ## What a geothermal system costs in Australia A geothermal system costs more upfront than an air source hydronic heat pump, because you are paying for the ground loop and the trenching or drilling that goes with it, on top of the heat pump and the distribution. We do not publish a headline price for a complete geothermal system, and we would be wary of anyone who does, because the loop design, the ground conditions, the size of the home and the distribution all move the number. Every SóGeo geothermal project is quoted from drawings after a site visit, as a fixed quote against the design. What we can say is how the investment behaves. Our clients often see payback in 5 to 10 years through 50 to 70% lower running costs. A typical Melbourne home spends around $900 to $1,350 a year on electricity with a hydronic heat pump system, against around $4,100 a year running the same hydronic system on gas at current tariffs, and geothermal sits at the efficient end of that range. On a home with a heated pool, the summer heat recovery alone is typically worth $2,000 to $6,000 a year. And to be straight about incentives: there is currently no Victorian rebate for hydronic space-heating systems, geothermal included. Hot water heat pump rebates are a separate measure. Our [cost guide](/blog/how-much-does-it-cost-to-switch-from-gas-to-hydronic-heat-pumps) covers the hydronic side in detail. ## The honest downsides of geothermal Every heating technology has a shape, and geothermal’s is a high entry price for a very low running cost. The trade-offs, plainly: - **Upfront cost.** The ground loop is real money before the first winter, and it only pays back if you stay long enough or build to last. - **Site works.** Trenching needs open ground and boreholes need rig access. Both are solvable on most Melbourne blocks, but they need planning, and on a heritage overlay they need a permit conversation. - **Design risk.** An undersized or badly placed loop cannot be fixed with a bigger heat pump. The loop must be engineered for a 30-year horizon by someone who has done it before, and there are not many of those in Australia. - **Not a quick swap.** A gas boiler to air source swap can keep your radiators and be done in days. Geothermal is a project with civil works, best planned into a build or a major renovation. What geothermal does not have: an outdoor fan unit, noise, weather sensitivity, or a refrigerant line running outside. And the loop outlives the next two heat pumps. ## Pool heating and hot water from the same system Geothermal pool heating is one of the quietest advantages of a ground source system. In summer the heat pump is cooling the house, and the heat it removes has to go somewhere. A de-superheater sends it into the hot water cylinder first, and once that is satisfied, into the pool or spa, at no running cost beyond the cooling you were already paying for. In the shoulder seasons the ground loop carries pool heating directly at the same high efficiency as the house. For a family with a pool this is often the line item that turns the payback from acceptable into obvious. ## Who installs geothermal systems in Australia? Fewer companies than you would expect, and even fewer that design the loop, supply the heat pump, install the hydronics and commission the whole system as one team. SóGeo does all four from Carrum Downs in Melbourne’s south east, across Melbourne and regional Victoria, with drilling delivered alongside our sister company GT Drilling. Whoever you talk to, ask four questions: will you run a room by room heat-loss calculation, what design horizon is the ground loop sized for, can you show measured SCOPs from your own projects, and who owns the result if the system underperforms. The answers separate a geothermal specialist from a heat pump reseller. *SóGeo designs, supplies and installs geothermal heating and cooling systems across Melbourne and regional Victoria, and is the exclusive Victorian distributor and installer of the Stiebel Eltron WPE geothermal range. If you are planning a build or a renovation, the right time to talk is before the slab is poured.* [*Start with a site visit and a heat-loss calculation*](/contact-us)*.* ## Common questions about geothermal heating and cooling ### What is the downside of geothermal home heating? ➕ The upfront cost of the ground loop, and the site works to install it. Running costs are the lowest of any heating system, the loop lasts 50 or more years, and there is no outdoor unit, so the downside is almost entirely at the start. It suits owners who are staying, or building to last. ### Is geothermal heating possible in Australia? ➕ Yes, and it has nothing to do with volcanoes or hot springs. Residential geothermal in Australia means a ground source heat pump using the stable temperature of the shallow ground, which in Melbourne sits in the mid-teens all year a few metres down. Systems are running today from heritage homes in Kooyong to coastal builds at Port Campbell and rural properties at Coimadai and Invermay. ### What is the cheapest way to heat a house in Australia? ➕ To run, a heat pump, and a geothermal heat pump above all, because it delivers 5 to 7 units of heat for every unit of electricity and pairs with rooftop solar. Gas is the most expensive way to heat a hydronic home at current tariffs, at around $4,100 a year for a typical Melbourne home against $900 to $1,350 with a heat pump. To buy, a gas boiler is cheapest today and the most expensive decision over ten years. ### How long does a geothermal system last? ➕ The buried ground loop lasts 50 or more years. The heat pump itself is a mechanical appliance with a service life of around twenty years, and it can be replaced without touching the loop. 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