In a residential building, nobody sees what a shower costs: tenants do not know how much they use, and managers only find out from the bill. The Molleaumètre displays it in real time, shower by shower, and cuts it by 23% per shower, a result measured by sensor in the Hénéo pilot (RIVP group), with no building work and nothing imposed on tenants.
The shower is the largest single use of hot water in a home. And hot water weighs twice: the cost of the water, plus the energy that heats it.
Without feedback, adapting behaviour is impossible: a tenant has no idea whether their shower uses 30 or 80 litres. Consumption stays invisible until the annual charge reconciliation.
Domestic hot water inflates tenants' recoverable charges and the landlord's energy bill alike. Every litre avoided eases both, a concrete lever against fuel poverty.
Posters and one-off campaigns produce effects that fade within weeks. What lasts is a reference point present at every shower, at the exact moment the water is running.
With Hénéo (RIVP group), Molleau equipped 30 homes, 28 of which were analysed, in a student residence in the 13th arrondissement of Paris, from 13 November 2025 to 30 June 2026, across 3,140 showers. A two-phase protocol: first a silent measurement to establish the baseline, then activation of the light ring. Same showers, same residents: only the visibility changed.
Read the full protocol and results →
The Molleaumètre screws onto the shower hose and measures every shower. No work on the water risers, no sub-meters to fit, and nothing required from the tenant.
Home by home, onto the shower hose, with no tools and no water shut-off. A few minutes per bathroom is enough to equip an entire residence.
Green, amber, red: residents see their consumption during the shower. Grounded in behavioural science (boost theory), with no guilt-inducing message and no change to pressure or flow.
Anonymised data sent automatically (self-powered, battery-free): before and after comparison by home and by site, conversion into euros and tCO₂e, and exports ready for your CSR reports.
Projection based on the volume measured during the pilot's baseline phase (45 L per shower) and a 25% reduction, a Molleau assumption.
| Per year | Average scenario · −25% | Heaviest users · −40% |
|---|---|---|
| Water saved | 410 m³11 L per shower | 655 m³18 L per shower |
| Savings (water + heating) | ≈ €4,300 *≈ €43 per home | ≈ €6,900 *≈ €69 per home |
| CO₂ avoided | ≈ 870 kg≈ 12,400 kWh of heating avoided | ≈ 1.4 t≈ 19,900 kWh of heating avoided |
* Indicative estimate calculated with the assumptions used in the Molleau calculator: water and sewerage at €4.69/m³ (French national average, SISPEA 2025), heating from 15 °C to 41 °C (around 0.030 kWh/L), electricity at €0.1940/kWh (French regulated tariff, June 2026), CO₂ at roughly 0.06 kg/kWh (French electricity mix) plus 0.30 kg/m³ (treatment and distribution). Several occupants per home, communal gas cylinders, local tariffs: every parameter can be adjusted in the calculator.
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By acting on the largest single use of hot water: the shower. The Molleaumètre screws onto the shower hose of each home in a few minutes, with no tools, no water shut-off and no plumbing. Measured result: 23% less per shower, and up to 61% less among the heaviest users.
One-off campaigns fade. What lasts is feedback at the moment the water is running. In the Hénéo pilot, the light ring cut consumption by 23% per shower and by 15.5% on the main meter, 83% of residents reported a new awareness, and median satisfaction reached 5/5 at six months (mean 4.4/5), with no constraint and no loss of comfort.
Yes. Each Molleaumètre measures the showers in the home and transmits its data automatically: self-powered by micro-turbine, battery-free and requiring nothing from the tenant. You track every home and every site on your dashboard, without touching the water risers.
Hot water weighs twice: the water itself and the energy that heats it. Cutting shower water by around a quarter directly reduces recoverable charges, a concrete argument in conversations with tenants and a lever against fuel poverty.
Installation takes a few minutes per bathroom, nothing is required from the resident and no app is needed. Shower data is anonymised. Residents in the pilot described it as “a benchmark”, not surveillance.
The Hénéo pilot (RIVP group): 30 homes equipped, 28 analysed, in the 13th arrondissement of Paris, with a two-phase sensor-measured protocol giving 23% less per shower and 15.5% less on the main meter. Rollouts are also under way with In'li, in a residence in Orsay. Read the announcement →
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