This topic has become unavoidable for owners of rental buildings in French-speaking Switzerland. The collective oil or gas boilers that still serve the majority of the housing stock built between 1960 and 2000 are reaching the end of their lives. Like-for-like replacement is no longer an option in most cantons, and the collective heat pump has become the primary route forward.
This transition raises questions specific to rental buildings: cost, rent pass-through, timelines, and coordination with tenants. It is a subject that combines technical, tenancy law, and fiscal dimensions. This article addresses these dimensions in a practical way, drawing on projects we accompany in collaboration with property managers across French-speaking Switzerland.
The regulatory context in 2026
The French-speaking cantons have tightened the rules governing the replacement of fossil heating systems. For a rental building, here is the practical situation:
Vaud, Geneva, Fribourg, Neuchâtel: like-for-like replacement of an oil boiler is strongly restricted or effectively prohibited, except where a proven technical impossibility can be demonstrated. A heat pump is expected by default.
Valais, Jura: rules are more gradual but aligned with the same trend. By 2030, like-for-like replacement will be exceptional everywhere.
Legal deadlines: there is no forced-replacement timetable for boilers currently in good working order in 2026. The constraint applies at the point of replacement, not before.
Listed buildings: specific rules apply depending on protection status. An exemption may be requested but requires a robust file.
For the owner of a rental building, the challenge is not to replace immediately but to plan ahead. A boiler of 20 years or more warrants a prospective study. A breakdown in the middle of winter in a 10-unit building is a logistical catastrophe that runs to thousands of francs in emergency costs and carries a letting risk (early departures).
How much does a collective heat pump cost in 2026
Costs for a building are calculated differently from those for a private house: the main equipment is more powerful, but economies of scale work in the owner's favour.
Building with 4–6 units (15–25 kW thermal): CHF 70,000 to CHF 105,000 fully installed.
Building with 8–12 units (25–45 kW thermal): CHF 95,000 to CHF 145,000 fully installed.
Building with 14–20 units (45–70 kW thermal): CHF 140,000 to CHF 200,000 fully installed.
Building with 25+ units: bespoke quotation; at this scale the design shifts to commercial heat pumps or a cascade arrangement.
These ranges apply to collective air-to-water heat pumps. Geothermal typically adds 35–45% to the base cost, justified by a higher SCOP and better performance in hard frost.
The main equipment changes. In a building, a residential monobloc is rarely installed. Instead, commercial heat pumps are used (Daikin EWYT, Mitsubishi Mr Slim Hybrid, Hitachi RHUE-AHN, Viessmann Vitocal 350-G), often in cascade to modularise output and provide partial redundancy in the event of a single unit failure.
The technical structure of a building project
A collective heat pump in a building is a complete system, more complex than a heat pump for a private house.
Plant room. The existing boiler room is generally reused after the oil boiler has been removed. The oil tank is decommissioned and dismantled, freeing up part of the room for the buffer tank and hydraulic components.
External unit. For an air-to-water system, the location of the external unit is critical. Ideally positioned at the rear of the building, on a concrete slab or supported structure, away from neighbouring bedrooms for acoustic reasons. In some buildings, two smaller units in cascade are preferred over a single large one, which improves modulation and reduces noise impact.
Buffer tank. In collective systems, a buffer tank of 500 to 1,500 litres is almost always required to absorb peaks and smooth output. Budget CHF 3,500–7,000 on top of the main equipment.
Collective domestic hot water cylinder. Collective hot water production requires specific consideration. The heat pump can produce the domestic hot water, or separate production can be retained (individual cylinders per flat — sometimes more efficient).
Distribution. The building's hydraulic network may need adaptation. Original radiators designed for a flow temperature of 70–80 °C must operate at 50 °C with the heat pump. This is rarely a blocking issue if the building is properly insulated, but it warrants a case-by-case study, flat by flat.
Rent pass-through: the sensitive issue
This is the central question whenever a rental building is involved. The Code of Obligations (Art. 269a) and cantonal ordinances govern the matter.
Basic principle. An energy improvement can be passed through to rents, but a simple like-for-like replacement cannot. As a heat pump replacing an oil boiler is considered a substantial improvement, part of the cost can be passed through.
Calculation method. In general, the so-called "improvement" share (typically estimated at 50% to 70% of the net cost) is amortised over the technical life of the installation (20 to 25 years for a heat pump). The calculation yields an annual charge that is distributed across the flats in proportion to the building's allocation key.
Legal ceiling. The increase cannot exceed certain thresholds and must be notified on the official cantonal form. Tenants may contest within 30 days.
Actual increases observed. On recent projects we have accompanied in Vaud and Geneva, the average increase has been between 4% and 9% of the net monthly rent, over a defined amortisation period. This should be compared with any heating charge savings (where charges are individualised), which may offset part or all of the increase for the tenant.
Good practice. Have the pass-through calculation validated by a tenancy law specialist before notification. An error in the calculation basis can block the entire procedure and give rise to protracted disputes.
The timeline for a building project
From decision to commissioning, allow 9 to 14 months for a well-prepared project. The detail:
Months 1–2. Thermal study of the building, output simulation, choice of concept (air-to-water, geothermal, hybrid). Visit to the plant room, identification of constraints.
Months 2–3. Detailed quotations (ideally 2–3 for comparison), discussion with the property manager on the charge/rent allocation and the pass-through method.
Months 3–4. Submission of cantonal grant application (Building Programme), municipal application if applicable, check on eligibility for the global renovation bonus if the building also needs insulation.
Months 4–5. Notification to the electricity grid operator, municipal permits if required.
Months 5–6. Tenant notification (formal letter), works notice, schedule of any planned supply interruptions.
Months 6–7. Installation. Allow 8–15 working days for a standard building, including 2–3 days without hot water for tenants (ideally scheduled in the shoulder season).
Months 7–8. Commissioning, fine-tuning, initial monitoring.
Months 8–12. Grant payments received, finalisation of rent increase notifications.
Planning 12 to 18 months before the boiler's presumed end of life is the minimum needed to manage this timeline without crisis.
Grants available for a rental building
Good news: cantonal grants apply in full to rental buildings. The French-speaking Swiss Building Programme makes no distinction between owner-occupiers and landlords.
For an 8–12-unit building in Vaud, typical amounts are:
- Cantonal Building Programme grant: CHF 18,000 to CHF 32,000.
- Global renovation bonus (if simultaneous insulation works): an additional CHF 10,000 to CHF 25,000.
- Municipal aid (depending on location): CHF 0 to CHF 8,000.
- Owner's tax deduction: 27% to 35% of the net cost, depending on the tax bracket.
On a project costing CHF 130,000 gross, the effective net cost after grants can fall to CHF 65,000–85,000. This is what makes the operation financially viable, and it is what justifies the "investment" share versus "replacement" share in the rent pass-through calculation.
Combining with collective photovoltaics
In a building with a usable roof, combining the heat pump installation with a collective solar installation under a self-consumption community (RCP) changes the financial equation.
The heat pump consumes 20,000 to 40,000 kWh/year for a standard building. A 30–50 kWp PV installation produces 30,000 to 50,000 kWh/year. Direct self-consumption by the heat pump can reach 50–70%, reducing the electricity bill by 30–50%.
Over 25 years, the additional cost of a PV installation (CHF 50,000–70,000 gross) is more than covered by the operational savings, and the building's carbon footprint improves radically. Many modern building owners now integrate both operations into a single project to benefit from synergies in the grant applications, administrative process, and construction works.
Our advice for landlords in 2026
Moving to a heat pump in a rental building is not an operation to improvise. Three principles apply:
Plan ahead. 12–18 months before the probable breakdown. The cost of an emergency project in the middle of winter exceeds that of a planned mid-season project by 30–50%.
Coordinate. Property manager, owner, installer, tenancy law specialist: all must be aligned on the timeline and the pass-through method. Conflicts arise when one party discovers the decision after the fact.
Assess global renovation. The heat pump alone delivers 60–70% savings on running costs. Combined with insulation, that rises to 75–85%. If the building is poorly insulated and works are foreseeable within five years, doing everything at once unlocks a better grant package and avoids repeated building works.
A heat pump project in a building is a 25-year investment that, when managed well, durably enhances the asset's value and stabilises tenants' running costs. Managed poorly, it creates letting risk and a budget that runs out of control. The difference lies in the preparation.