All the data Molleau publishes, gathered on one page: results measured by sensor, calculation assumptions and standard projections. Every figure is sourced and dated. This data is freely citable with attribution.
Sensor measurement in real conditions: 30 homes equipped, 28 analysed, in a Hénéo student residence (RIVP group) in the 13th arrondissement of Paris, from 13 November 2025 to 30 June 2026, across 3,140 showers, in two phases (silent baseline, then light ring active).
| Indicator | Value | Source and period |
|---|---|---|
| Average consumption per shower, before | 45 L | Phase 1 (silent sensor), Hénéo pilot. Full protocol |
| Average consumption per shower, after | ≈ 35 L | Phase 2 (light ring active), derived from the measured 23% reduction |
| Average reduction per shower | −23% | Phase 1 versus phase 2, same showers, same occupants, across 3,140 showers |
| Reduction among the heaviest users | up to −61% | Hénéo pilot: the higher the starting consumption, the larger the reduction |
| Reported change in awareness | 83% | Resident survey at one month, Hénéo pilot |
| Overall satisfaction | 5 / 5 | Median at the six-month resident review (mean 4.4 / 5); all 7 respondents recommend the device |
In the Hénéo pilot (RIVP group, Paris 13th arrondissement, 30 homes equipped of which 28 analysed, 13 November 2025 to 30 June 2026, 3,140 showers), switching on the Molleaumètre light ring cut consumption by 23% per shower and by 15.5% on the building's main meter, with reductions of up to 61% among the heaviest users, with no change to flow or pressure. Source: Molleau, molleau.com/en/key-figures.html.
Every estimate Molleau publishes rests on these assumptions, all adjustable in the online calculator.
| Parameter | Value | Basis |
|---|---|---|
| Average domestic consumption in France | 150 L/day | Per person, all domestic uses (drinking, cooking, washing). 150 L in 2022, 145 L in 2023, from SISPEA reports by the French national observatory for water and sanitation services |
| Domestic water per hotel night | 150 L | Average assumption per night per guest, of which at least 100 L for the shower. Consistent with the 2024 French DGE study (240 to 323 L per night across all uses depending on the segment, of which 40 to 45% for cleaning) and with national domestic consumption (SISPEA) |
| Average volume of a shower | 45 L | Value measured during the baseline phase of the Hénéo pilot |
| Price of water (supply + sewerage) | €4.69/m³ | Approximate French national average, to be adjusted to the local tariff |
| Heating energy per litre | 0.030 kWh/L | Heating water from 15 °C to 41 °C (shower temperature) |
| Price of electricity | €0.1940/kWh | French regulated tariff, to be adjusted to the contract and heating source (gas, heat pump) |
| Emissions per kWh of electricity | ≈ 0.06 kg CO₂ | Average French electricity mix |
| Emissions from drinking water | ≈ 0.30 kg CO₂/m³ | Production, treatment and distribution of water |
Indicative estimates using Molleau assumptions: lower ranges calculated at 25% savings, upper ranges at 40% for the heaviest users. These rates are deliberately conservative against the reductions measured in the pilot (23% on average, up to 61% among the heaviest users).
| Water saved per year | 465 to 745 m³ |
| Savings per year (water + heating) | ≈ €4,900 to €7,900 * |
| CO₂ avoided per year | ≈ 1 to 1.6 t |
| Water saved per year | 410 to 655 m³ |
| Savings per year (water + heating) | ≈ €4,300 to €6,900 * |
| CO₂ avoided per year | ≈ 0.9 to 1.4 t |
* Indicative estimates calculated with the assumptions in section 2, all adjustable in the calculator. Actual results depend on your property, your tariffs and your heating source.
These figures are published under a CC BY 4.0 licence, so you may reuse them freely with attribution. Suggested citation:
Molleau, “Key figures”, molleau.com/en/key-figures.html, accessed June 2026. Hénéo pilot (RIVP group), Paris, 13 November 2025 to 30 June 2026, 3,140 showers: 23% less per shower, 15.5% less on the main meter, up to 61% less among the heaviest users.
Need the detailed protocol, the full report or an interview? Contact the team, we reply within 48 hours. The full pilot report is available on request.
The calculator applies these assumptions to your portfolio: hotel rooms or homes, occupancy rate and local tariffs.