In Geneva, the IDC now triggers legal obligations for building owners — and a retrofit is first and foremost a matter of strategic choices. This dossier sets out the framework: IDC thresholds, the EnerPHit and Minergie-P Rénovation standards, project approach and phasing. Implementation — envelope, airtightness, systems — is detailed in the practical dossier.
A large share of the Swiss building stock was built before the first meaningful thermal requirements of the 1980s, without significant insulation. The order of magnitude can be read off the Geneva regulations: above 125 kWh/m²·an (450 MJ/m²·an) of heating expenditure indexThreshold set by the Geneva REn (rsGE L 2 30.01, art. 14): above 125 kWh/m²·an (450 MJ/m²·an), an energy audit and improvement measures are required.République et canton de Genève — Règlement d'application de la loi sur l'énergie (REn), rsGE L 2 30.01, art. 14 et 14B, an energy audit becomes mandatory — an unrenovated building from that era frequently crosses that threshold. Switzerland has set itself the target of carbon neutrality by 2050Confirmed by the SFOE: net-zero CO₂ emissions by 2050, with building stock consumption cut from around 90 TWh to 65 TWh.Office fédéral de l'énergie (OFEN/BFE) — Buildings — Energy efficiency: this means deeply retrofitting most of this building stock, not just replacing boilers.
A superficial retrofit (replacing windows, a more efficient gas boiler) brings only a marginal improvement. Only a coordinated envelope + systems retrofit can divide heating consumption by a factor of roughly 5 — from the 125 kWh/m²·an of the Geneva audit thresholdFactor derived from two sourced values: the Geneva audit threshold of 125 kWh/m²·an (REn art. 14) and the EnerPHit target of ≤ 25 kWh/(m²a) (PHI criteria) — a ratio of about 5.Passivhaus Institut, Darmstadt — Criteria for the Passive House, EnerPHit and PHI Low Energy Building Standards down to the ≤ 25 kWh/m²·an targeted by EnerPHit — and achieve lasting thermal comfort.
In Geneva, owners of heated buildings declare their building's IDC — Indice de Dépense de Chaleur (heating expenditure index) to the OCEN each year: the actual heating and domestic hot water consumption, measured at the meters and expressed per unit of reference energy floor area. It is not a theoretical calculation — it is the building's real energy bill. Not to be confused with individual heating-cost accounting, which applies to buildings with at least 5 heat off-takers (REn art. 14B)Two distinct regimes in the Geneva REn: the IDC (art. 14) applies to owners of heated buildings; individual heating-cost accounting (art. 14B) applies from 5 off-takers.République et canton de Genève — Règlement d'application de la loi sur l'énergie (REn), rsGE L 2 30.01, art. 14 et 14B: that is a separate rule, unrelated to the scope of the IDC.
This index is no longer just a monitoring tool: it triggers legal obligations for building owners.
Two main standards define "passive retrofit" in French-speaking Switzerland: EnerPHit (Passivhaus Institut, Darmstadt) and Minergie-P Rénovation. Their requirements differ in logic, but their shared goal is to reach a performance level close to new passive construction, while accounting for the constraints of the existing building stock.
Take care when comparing the numerical thresholds: the reference energy floor area (SRE) is not calculated the same way between Passivhaus (PHPP reference floor area, PHI Darmstadt) and Minergie® (SRE per SIA 416). The two requirements are not even of the same kind — EnerPHit sets an absolute value (≤ 25 kWh/m²·an), Minergie-P a percentageNo Minergie document sets an absolute "≤ 30" value: regulation 2026.1 expresses retrofit as a % of MoPEC 2025 (≤ 90 %), with a 15 kWh/m²·an floor.Minergie Suisse — Règlement des labels MINERGIE®/MINERGIE-P®/MINERGIE-A®, version 2026.1 of the MoPEC 2025 limit values — so that a direct comparison of the figures would make no sense.
| Criterion | Passivhaus New Build | EnerPHit Retrofit | Minergie-P New Build | Minergie-P Retrofit |
|---|---|---|---|---|
| Heating demand | ≤ 15 kWh/m²·an | ≤ 25 kWh/m²·an | ≤ 70 % MoPEC 2025 | ≤ 90 % MoPEC 2025 |
| Airtightness * | n₅₀ ≤ 0,6 h⁻¹ | n₅₀ ≤ 1,0 h⁻¹ | qE50 ≤ 0,8 m³/(h·m²) | qE50 ≤ 1,6 m³/(h·m²) |
| Heating capacity | ≤ 10 W/m² | — | ≤ 10 W/m² | — |
| Phased certification | — | ✓ Components | — | — |
| Calculation tool | PHPP | PHPP | SIA 380/1 | SIA 380/1 |
| Protected buildings | — | ⚠ Case by case | — | — |
* Passivhaus/EnerPHit measure n₅₀ (air changes per volume), Minergie® measures qE50 (leakage flow rate per envelope surface area, EN ISO 9972:2015 + SIA 180:2014Edition in force for air permeability measurement: ISO 9972:2015, complemented by SIA 180:2014 for Swiss application.Minergie Suisse — Règlement des labels MINERGIE®/MINERGIE-P®/MINERGIE-A®, version 2026.1) — the two quantities are not directly comparable. Minergie® values according to regulation 2026.1 (fossil fuels prohibited, absolute minimum of 15 kWh/m²·an)Minergie regulation 2026.1, sec. 8.1: fossil fuels not allowed for heat generation, with narrow exceptions (peak load ≤ 10 % above 80 kW; district heating ≤ 50 % fossil).Minergie Suisse — Règlement des labels MINERGIE®/MINERGIE-P®/MINERGIE-A®, version 2026.1.
A passive retrofit cannot be improvised after the fact: decisions made at the design stage determine 80% of the result. Here is the typical sequence of a well-run project.
How much does a retrofit to the passive standard cost?
Costs vary enormously depending on the building's initial condition, its geometry, the presence of structural thermal bridges, and the choice of materials: there is no public cost database that would allow a reliable price per m² to be quoted for a retrofit to passive level, and any serious costing requires a quotation on the actual building. What is public and quantified, by contrast, is the support. In Geneva, measure M-13 "HPE retrofit, CECB® variant" pays 390 CHF/m²GEnergie rate, measure M-13 "HPE retrofit, CECB® variant": 390 CHF/m² for single-family housing, 210 CHF/m² collective, 150 CHF/m² other uses. Revised annually.GEnergie / canton de Genève — HPE — Rénovation variante CECB®, mesure M-13 of heated floor area for single-family housing and 210 CHF/m² for collective housing; the 2026 cantonal budget amounts to CHF 80 millionCanton of Geneva announcement of 2 February 2026: CHF 80 million in energy subsidies for 2026, CHF 10 million more than in 2025.République et canton de Genève — Subventions énergétiques 2026 : 80 millions de francs pour accélérer la rénovation du parc bâti genevois. Since the rates are revised annually, they should be checked before any application. The return on investment is also measured in comfort, property value, and protection against energy price volatility.
Can a retrofit be done in stages without doing everything at once?
Yes — it is even the most common situation. The key is to design the project as a whole before starting the first phase, to ensure that each intervention is consistent with those that follow. The rule: start with the roof (the most cost-effective energy-wise), then the façades, then the windows (taking into account their final position within the insulated wall), then the systems. Never replace the windows before deciding on the façade insulation system.
What is the difference between a "Minergie" retrofit and an "EnerPHit" retrofit?
Both standards target a similar level of performance and allow a component-based approach. Minergie-P is more widely recognized in the Swiss context, with a well-established cantonal procedure and better integration into subsidy applications. EnerPHit is the Passivhaus Institut's international standard: it is recognized outside Switzerland and its PHPP methodology is very precise. In practice, building owners in Geneva or Vaud will often choose Minergie-P Rénovation for its administrative ease, while EnerPHit will be preferred for projects with strong technical stakes or an exemplary role.
Every figure and every claim in this dossier links back to its source. Hover or tap a footnote marker to see it.
Envelope strategy and critical review of the file — let's talk about your building and its timeline.
Get in touch