The GEAK – the cantons' building energy certificate – rates a building in efficiency classes from A to G, separately for the building envelope and overall energy. A solar system improves the overall-energy rating, because self-produced electricity relieves the balance – it changes nothing in the envelope class. The GEAK becomes relevant on sale, in renovation planning, and sometimes as a prerequisite for funding or proof. (As of: July 2026)
Key points in brief
- The GEAK is the official, nationwide-uniform energy certificate for buildings – issued by certified professionals.
- It rates two things separately: the quality of the building envelope and overall energy efficiency, each in classes A to G.
- A solar system improves the overall-energy class; the envelope class remains a matter of insulation and windows.
- The "GEAK Plus" adds an advisory report with renovation options to the certificate – valuable as a roadmap.
- The GEAK is mandatory only in certain constellations (varies by canton, for example with funding or on change of ownership).
What is the GEAK – and what does it tell you?
The GEAK is the official energy certificate for buildings in Switzerland – run by the cantons, uniform nationwide, issued by certified GEAK experts. It answers at a glance what otherwise stays hidden in construction documents: how efficient is this house?
It gives that answer in two parts, and that split is the key to understanding it:
The envelope class rates the quality of the building envelope – insulation, windows, roof. It shows how much heat the house loses, regardless of what it's heated with.
The overall-energy class rates the building's total energy demand including building services – heating, hot water, electricity – and factors in self-production.
Both scales run from A (best) to G (worst class). An older building with oil heating typically lands in the back letters; a modernised house with a heat pump and solar system moves noticeably forward in overall energy. Anyone who additionally wants to know how their own house can move forward orders the "GEAK Plus": it adds an advisory report to the certificate with concrete renovation options, including their effect and order – often the actually valuable part of the document as a modernisation roadmap.
How does the solar system improve my GEAK rating?
Via the overall-energy balance. The logic is intuitive: the GEAK looks at how much (non-renewable) energy the building needs – and a solar system that covers part of the electricity demand itself directly relieves that balance. The system makes the house measurably better in the certificate, specifically in the overall-energy class.
Just as important is the opposite: the solar system changes nothing in the envelope class. A poorly insulated house stays poor in the envelope rating even with a full solar roof – the modules don't insulate. That very separation is what makes the GEAK honest: it can't be "dressed up" with a single measure, it shows where the building actually stands.
That gives a sensible reading for practice:
| Your goal | What the GEAK shows | Matching measure |
|---|---|---|
| Better overall energy | Demand vs. self-production | PV, heat pump, efficient technology |
| Better envelope | Heat losses | Insulation, windows (Gebäudeprogramm) |
| A roadmap for everything | GEAK Plus with options | Order according to the report |
Simplified overview, as of: July 2026. The current GEAK rules and the assessment of the GEAK professional are decisive.
The combination also explains why a heat pump and PV are a strong duo in the GEAK: the heat pump replaces fossil energy with (partly self-produced) electricity, and the system produces it – the overall-energy class rewards both together more than either measure alone. That's the same system logic that shapes Minergie; the GEAK is, in a sense, its certificate format.
When do I need a GEAK – and when is it worth getting voluntarily?
The GEAK is mandatory only in certain constellations, and those vary by canton: some cantons require it on a change of ownership, many funding programmes require a GEAK or GEAK Plus for certain contributions, and in the Canton of Zurich it plays a role as proof of efficiency for heating replacement. Whether your project requires a GEAK is clarified by checking the relevant funding regulations or cantonal requirement – there's no blanket answer.
It's worth getting voluntarily above all at three moments. Before a larger modernisation, because the GEAK Plus puts the measures in a sensible order – protecting against the classic trap of building in individual measures in the wrong sequence. On selling the property, because a good certificate documents the energy condition and makes it easier for buyers to assess. And as a status check, when you simply want to know where your own house stands.
What the GEAK is not: a prerequisite for the solar system. PV can be planned and built independently of any certificate – the GEAK documents its effect, it doesn't require it.
We encounter the GEAK in projects mostly from two sides. One: customers need it as a prerequisite – for a funding programme or as proof – and are surprised to discover how concretely the GEAK Plus report maps out the next steps. The other: the question "will the solar system move my house into a better class?" – and there the answer is a clear yes for overall energy, combined with the honest note that the envelope class stays unaffected. Our advice for anyone modernising anyway: get the GEAK Plus early and place the solar system as one building block in the roadmap. Then the measures don't compete, they build on each other.
Frequently asked questions
Do I need a GEAK for the solar system?
No – the system can be planned, approved and built without any energy certificate. The GEAK documents the system's energy effect in the certificate but isn't a prerequisite. It only becomes relevant if your project requires a GEAK for some other reason, for example a funding programme.
How much does a solar system improve the GEAK class?
That depends on the building – on its size and demand, on the system size and the rest of the building services. Blanket class jumps can't seriously be promised. The direction is certain: self-production improves the overall-energy balance, and the GEAK professional can calculate the effect for your house concretely.
What does a GEAK cost?
The cost depends on the building and the variant (GEAK or GEAK Plus with an advisory report) and is quoted by the issuing professional. Some cantons or programmes contribute to the cost. Current figures are available from the cantons' official GEAK platform.
Is the GEAK the same as Minergie?
No – the GEAK is a certificate of the current state, Minergie is a construction standard with a label for new builds and modernisation. They complement each other: the GEAK shows where the house stands; standards like Minergie define where a modernisation can lead.
Does my GEAK go out of date if I renovate?
The certificate describes the condition at the time it was issued – after significant measures (insulation, heating replacement, solar system) it's worth updating it, so the certificate shows the new state. Especially after a modernisation, the updated GEAK is the document that proves the increase in value.
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Sources: GEAK – the cantons' building energy certificate (official platform, rules in force at the time), cantonal energy requirements (ZH), empirical data from ecoEn GmbH's modernisation practice, Zurich region.
Last updated: 9 July 2026 · Author: ecoEn editorial team
