Heat lies
beneath your feet.

The borehole probe itself is completely silent — it sits in the ground, with no moving parts. Only the heat pump in the plant room is audible, and that too is very quiet.

Modern brine-water heat pumps reach sound pressure levels of 35–45 dB(A) in the installation room — comparable to a refrigerator or quiet conversation. In a sound-insulated plant room (standard in Swiss new builds) the heat pump becomes practically inaudible outside the room.

The big difference vs. air-water heat pumps: no outdoor units. So no noise to the neighbourhood either — relevant under the Swiss Noise Abatement Ordinance (NAO), which sets limits of 45–60 dB(A) for outdoor units depending on sensitivity level.

During the drilling phase, construction noise arises (typically 80–90 dB(A) at the drill head). We clad the drilling mast with noise shields, keep within the VLE/VLD limits and restrict drilling hours to weekdays 07:00–18:00.

For a typical single-family home, probe depths are 120–220 m. The exact depth comes from three factors: heating load of the building, geological parameters (thermal conductivity of the underground) and number of probes.

Sizing is done by the specialist planner per SIA 384/6 (Swiss standard for borehole heat exchangers, 2021 edition) — we contribute practical experience and execute it precisely. Rule of thumb: about 100 kWh/year per drilled metre for a single probe; with several probes in a field this value drops by 10–20 % due to mutual influence.

Example calculation for a SFH with 18'000 kWh/year heat demand: required probe metres ≈ 180 m. That can be one 180 m probe or two of 90 m each — depending on space, geology and probe-field geometry.

We go up to 500 m deep (special probes up to 600 m with PN 50 steel coaxial technology). Every borehole is surveyed with an inclinometer — deviation from vertical typically ≤ 1 % over the total depth.

Yes, in all 26 cantons. Borehole heat-exchanger drilling is subject to concession or permit, in different forms depending on the canton.

Two main procedures: drilling notice (simplified, approx. 4 weeks processing) and the cantonal building application (more complex, up to 8 weeks). Some cantons (e.g. AG) process within 4 weeks, others need 6–8 weeks.

The site's suitability is classified via the GeoHP map (federal / cantons) into three zones:

• Suitable — standard procedure, Midlands and pre-Alps
• With conditions — protection zones S3/Au, karst, additional evidence required
• Restricted — protection zones S1/S2, unstable slopes: evaluate alternatives

In groundwater protection zones S1 and S2, borehole probes are usually prohibited. Karst areas in JU and CH require case-by-case review. We check the GeoHP map before contract conclusion, prepare the entire dossier and support you with the submission.

At least 50 years per SIA 384/6 — many manufacturers quote 100 years for the pipe material. The probe itself is completely passive underground, with no moving parts, no wear.

We use crack-resistant PE 100 RC polyethylene, which per manufacturer testing remains pressure-stable for over 100 years. The bentonite-cement grouting stays permanently tight thanks to its permeability ≤ 1 × 10⁻⁷ m/s.

What gets replaced over time:

• Heat pump: after 20–25 years the state of the art is outdated → new unit, probe connection stays
• Brine fluid: check every 15–20 years, top up if needed (antifreeze, pH)
• Manifold components: wear check after 30+ years

What never gets replaced: the borehole and the probe pipes. Those who invest today still benefit in the next generation.

Yes — the decisive factor is the flow temperature of the heating system. Heat pumps work most efficiently at low flow temperatures. Ideal: 35–45 °C (underfloor heating). At flow temperatures > 55 °C the SPF drops significantly.

Older buildings with radiators: often 60–70 °C flow. But that is often overdesigned. A calculation shows: for most days of the year 45–50 °C is enough — only on the coldest days higher flow temperatures are needed. Here either:

• Radiator enlargement: replace single radiators (living room, cold rooms) with larger ones — cheap, effective
• Buffer tank: smooths peak loads
• Hybrid with peak-load boiler: switched on only on the 10–15 coldest days

During a renovation, subsidies can also be combined: heating replacement + windows + insulation = up to CHF 20'000 federal funding possible.

Total investment typically CHF 55'000 – 80'000 for an average SFH (200 m², 18'000 kWh/year). Breakdown:

• Borehole & probe: CHF 25'000 – 35'000 (about CHF 130/m + manifold)
• Heat pump: CHF 15'000 – 22'000
• Installation, hydraulics, control: CHF 10'000 – 15'000
• Permit procedure, planning: CHF 2'000 – 4'000
• Heat pump connection, electrical upgrade: CHF 3'000 – 5'000

Subsidies: the national Building Programme typically pays CHF 5'000 – 9'000 per SFH (varies by canton). Plus tax deduction (energy-saving measure) over several years.

Operation: about CHF 1'300/year incl. maintenance (brine-water HP SPF 5.0 · CH electricity price 28 Rp/kWh 2025). Comparison: oil heating about CHF 3'050/year, gas about CHF 3'000/year, air-water HP about CHF 1'950/year.

Payback: for fossil → geothermal heating replacement, break-even after around 19 years compared to oil (before subsidies; sooner with rising energy prices or with subsidies). The PV variant pays back somewhat later because of the higher initial investment, but is the cheapest over the whole service life — around CHF 63'000 saved compared to oil, geothermal-only around CHF 52'000. System lifetime: 25 years heat pump + up to 80 years probe.

With correct sizing per SIA 384/6: no. The probe extracts heat from the ground in winter, the soil regenerates in summer through two mechanisms:

• Geothermal heat flow from below (about +3 °C per 100 m depth)
• Solar heat input from above (solar radiation, infiltration water)

Over a system's lifetime (50–80 years) the mean probe temperature can fall by 1–2 °C. That is normal and accounted for in SIA sizing. For systems that are undersized (probe metres too short, probe spacing too tight), the ground can cool further — efficiency loss is the consequence.

With geocooling in summer (passive cooling of the house via the probe), the soil is additionally regenerated. That's not just a comfort gain — it extends system life and stabilises the SPF over decades.

Long-term studies at home and abroad (Sweden, Switzerland, Germany) confirm stable source temperatures over 30+ years of operation when the probe is sized to standard.

Yes — and it is the most economical and most ecological combination possible today. During the day the heat pump is a grateful consumer of PV electricity.

Example setup for a typical SFH:

• PV system 10 kWp (50–60 m² roof area) → produces about 9'000–10'000 kWh/year
• Heat pump consumes 3'600 kWh/year (18'000 kWh heat ÷ SPF 5.0)
• Self-consumption share HP+household: 50–70 % of PV production
• Battery storage (optional, approx. 10 kWh): raises self-consumption to 70–80 %

Economics: heating costs drop to about CHF 800/year (vs. CHF 1'300 without PV). Over the PV system's 25-year life, that saves about CHF 12'500 vs. the standalone geothermal setup.

CO₂ footprint: with PV self-power, the HP's CO₂ share drops from about 216 kg/year to below 70 kg/year. Over its lifetime, practically CO₂-neutral.

Not necessarily a "garden" in the classic sense — but some space for the drilling rig and an access route.

Typical space requirements:

• Rig setup area: approx. 4 × 6 m, level ground
• Access: 3 m wide, load capacity ≥ 18 t
• Material area: 3 × 5 m for probe, grouting material, water tank
• Crane swing area if needed (city, tight conditions)

For special situations we have in-house drilling rigs on Aebi and Unimog platforms that get through narrow yard accesses, slopes and mountain terrain where standard rigs fail.

Visible after drilling: only the probe head — usually sunk in a shaft, covered with a lid, fully walkable. Garden, front yard or asphalt can be fully restored.

We do — Broder AG. On the borehole, probe and grouting we give the SIA-compliant warranties per SIA 384/6 and general Swiss contract law (CO).

For the heat pump, the manufacturer's warranties apply — typically 2–5 years, extendable up to 10 years for a fee. We handle the warranty case: one point of contact, no interface ping-pong.

Since we have been in Sargans since 1961 and work in the 3rd generation, you do not depend on a subcontractor that disappears in five years. Our typical maintenance:

• First year: free check-up after commissioning
• Every 2–3 years: heat pump maintenance visit (with manufacturer service)
• Every 5 years: brine-pressure check, pH value, antifreeze concentration
• 24/7 emergency service: for active maintenance contracts

No — with correct execution. Borehole heat exchangers count among the most environmentally friendly heating methods. Three common concerns in practice:

1. Brine fluid: typically 25–30 % propylene glycol (biodegradable, non-toxic, food-grade). In a leak practically harmless to soil and groundwater.
2. Bentonite grouting: natural clay mineral, chemically inert, cleanly seals the borehole and prevents material exchange between groundwater layers.
3. Impact on the underground: thermally by a few degrees, hydraulically unchanged. Unlike deep geothermal, no interference with the water cycle.

In return, a geothermal system saves about 225 t CO₂ over its lifetime (vs. oil). The "embodied energy" of a borehole (PE pipes, bentonite, drilling-rig diesel) is CO₂-amortised after 1–2 years of operation.

Leaks are extremely rare since probe pipes are pressure-tested and the probe field + HP is designed as a closed loop. If something happens, immediate detection is standard:

• Pressure-loss alarm: the HP controller detects any pressure drop in the brine circuit immediately and shuts down
• Brine pressure gauge: readable at the manifold, regularly checked
• Brine level sensor: reports level loss in the expansion vessel

In case of repair: isolate the affected probe circuit (shut-off valve at the manifold), locate the leak (usually in the manifold room or connection), repair without shutting down the whole system. The probe pipes themselves (PE 100 RC) have no leak history in 50+ years of observation.

No — shallow borehole heat exchangers (up to 600 m) do not trigger perceptible earthquakes. What was observed in a few Swiss cases (Basel 2006, St. Gallen 2013) was deep geothermal with boreholes over 3'000 m where high-pressure water was injected into the underground.

With borehole heat exchangers, by contrast:

• Drilling without high-pressure injection
• Borehole diameter only 13–17 cm (no cavity)
• Immediate bentonite grouting after probe installation
• Maximum depth well below geologically active layers

In karst areas (CH, BL, JU) we carefully check the geology before drilling to avoid cavities and water paths. These areas are classified as "with conditions" on the GeoHP map.

With correctly executed boreholes, practically not. Three protection mechanisms prevent impairment:

1. Borehole grouting: bentonite cement with permeability ≤ 1 × 10⁻⁷ m/s — tighter than the surrounding soil, no water exchange between groundwater layers
2. Probe pipes tight: PE 100 RC is diffusion-tight, no brine migration into the surrounding soil
3. Pressure test per SIA 384/6: every system documented tight at commissioning

In groundwater protection zones S3/Au (protection areas around drinking water sources), additional requirements apply: special grouting materials, higher pressure testing, online monitoring. In zones S1 and S2 borehole probes are generally prohibited — here air-water HP or district heating would be alternatives.

In summer the heat pump for heating is idle. But the probe can be used for passive cooling (geocooling / free cooling) — perhaps the biggest "bonus" a geothermal system offers vs. oil/gas.

How it works: brine at about 12 °C circulates directly from the ground through the heat exchanger and cools the heating circuit (floor or ceiling). The heat pump stays off. Power consumption: only the circulation pump (approx. 100 W).

Cooling capacity typically 2–4 °C below room temperature — usually enough for a comfortable indoor climate, even in hot summers. Bonus: the ground is reheated in summer — regeneration for the next winter.

For higher cooling capacity (office buildings, comfort needs) there are reversible heat pumps that can actively cool in summer (process reversal). With these, 6–8 °C below room temperature is possible.

Heat pumps are extremely reliable today — typical failure rate < 1 % per year. If something happens:

• Self-diagnosis: modern HPs report the fault via app / display and often contact service automatically
• Buffer tank: typically 300–500 litres, bridges several hours without HP operation
• Emergency heating (E-element): many systems have an electric backup heating element that steps in
• Repair: usually within 24–48 h by manufacturer service or us as system caretaker

For builders with high comfort needs we offer maintenance contracts with 24/7 emergency hotline and stocked spare parts for the most important components. On a maintenance-contract customer system, typical response time is < 12 h.

Yes — modern heat pumps invariably have smart-home integration. Via app you see:

• current power consumption and heat output (live + history)
• brine flow/return temperature (efficiency indicator)
• day-current SPF calculation
• heating curve adjustment
• hot water programme
• geocooling mode (summer)

Standards: SG-Ready (smart-grid capable — for PV self-consumption optimisation), MQTT, Modbus, EEBus (cross-manufacturer). Integration into Home Assistant, ioBroker, OpenHAB is easily possible.

For builders without tech interest: by default everything runs automatically. You don't need to do anything except commission maintenance once a year.

Probe boreholes are executed from the outset with SIA-compliant grouting so they can be decommissioned without consequences. On decommissioning (e.g. after 80 years of operation):

1. Remove probe head: dismantle manifold, seal connection stubs
2. Brine disposal: properly by certified disposer (propylene glycol is biodegradable but declared as special waste)
3. Probe pipes: stay in the ground — the bentonite grouting guarantees hydraulic tightness over centuries
4. Borehole documentation: remains in the cantonal borehole register (SFOE database), available for any follow-up projects

As of 2024, in Switzerland there is not a single documented dismantling of a BHE system — all systems to date are in operation, many since the early 1980s. The question will only arise in practice in the 2050s.