The most searched question about this technology and the one most contractors refuse to answer before a site visit. Here is the honest shape of it, with the assumptions on the table.
Because the number genuinely does depend on the ground. Two identical buildings on opposite sides of the same road can differ by tens of thousands of dollars in drilling cost, because one sits on rock and the other on overburden.
That is a real reason, not an evasion. But it is used as an excuse to avoid saying anything useful at all, so here is what actually moves the number.
| Driver | Why it matters |
|---|---|
| Total load | Sets how many tons, which sets how many metres of bore. The largest single factor. |
| Geology | Rock drills slower and costs more per metre than overburden, but conducts heat better, so you may need fewer metres. The two partly offset. |
| Loop type | Horizontal is cheaper per ton than vertical — if you have the land. Pond is cheaper again where it is possible at all. |
| Site access | A rig that cannot reach the drilling location changes everything. Urban sites carry mobilisation and restoration costs rural sites do not. |
| Annual balance | A heating-dominated building needs a larger field than a balanced one of the same peak load. This surprises people. |
| Distribution inside | Existing ductwork or hydronics may be reusable, or may not. On a retrofit this can rival the loop cost. |
On a commercial system, the Clean Technology Investment Tax Credit returns 30%, refundable, including the loop field.
That is worth sitting with. On most building measures the incentive applies to equipment. Here it applies to the ground works too — which is where most of the money goes. It is the most favourable treatment of any building measure in Canada, and it runs to 31 December 2033.
A ground source system that looks expensive against an air-source alternative at gross cost can look quite different at net cost, because the credit lands hardest on exactly the component that made it expensive.
We model both options at net cost, not gross. If air-source still wins, we will say so — see the suitability check, which exists to say no.
The saving is real and it is largest where the alternative is electric resistance or oil. Against a modern condensing gas system in a region with cheap gas and expensive electricity, the operating saving alone may not carry the capital — which is why carbon cost, equipment life and the credit usually have to be part of the case rather than an afterthought to it.
No federal credit applies to a house. Ontario residential incentives are covered on the residential page, including what ends on 30 November 2026. Financing is available on qualifying projects.
Because the drilling component — the largest part — varies with geology and access more than with tonnage. A price per ton would be a number we knew to be unreliable, which is worse than no number.
It depends far more on what you are replacing than on the ground source system itself. Against electric resistance or oil it is short. Against modern condensing gas it is long enough that the case usually rests on the federal credit, equipment life and carbon cost together.
On a commercial system, the qualifying property includes the ground loop. That is what makes the credit so much more valuable here than on other measures.
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Tell us the building, the site and how long you expect to own it. If ground source is wrong for you, that is the first thing we will say.