Water, energy & carbon waste

See what your shower flow rate is really costing you.

Older showers commonly run at 8–12 litres per minute. Modern low-flow options typically deliver a comparable feel at 5–6 L/min. Enter your site details to estimate the difference.

Every litre/min reduced compounds daily across every shower, every use, every day of the year.

Build your scenario

Shower savings calculator

1. Your current site

Duration and usage pattern default to published hotel guest-room benchmarks (EU JRC Best Environmental Management Practice in the Tourism Sector); current flow rate defaults to a conservative 10 L/min planning figure — adjust all of these to match your own site.

Number of showers Typically the number of guest rooms/en-suites. Current flow rate Conservative planning figure, producing an “up to 50%” saving. EU JRC’s guest-room model assumes 15 L/min for existing hotel showers (rising to 20+ L/min for premium multi-head showers) — use that or your own measured flow rate for a higher result, provided it reflects an actual measurement. Uses per shower per day Average uses per installed shower per calendar day, adjusted for occupancy (EU JRC models roughly one shower per guest-night). Increase for high double-occupancy or short-stay/high-turnover sites. Shower duration EU JRC’s guest-room savings model assumes a 6-minute shower per guest-night.

2. Your utility costs

Use your own billed rates for an accurate result.

Water supply & disposal cost Typical UK commercial combined water + wastewater rate, 2026 — but this varies far more by region than gas or electricity (roughly £1.50–£4.50+/m³ depending on your local water company and retailer). Check your own bill for an exact figure. Proposed flow rate Modern low-flow showers typically deliver 5–6 L/min. Gas cost Typical UK commercial gas rate, 2026 (range ~6.5–9p depending on volume and contract). Electricity cost Typical UK commercial electricity rate, 2026 (range ~22–30p; smaller sites often pay more, large half-hourly sites less). Boiler efficiency Purchased energy is always higher than the useful heat delivered to the water. Typical gas boiler efficiency is 85–90% — older central hotel plant may be lower.

How is your shower water heated?

How this is calculated Litres saved = (current − proposed flow rate) × duration × uses/day × number of showers × 365. Duration and usage pattern default to the EU Joint Research Centre’s hotel guest-room water model (Styles, Schönberger & Galvez Martos, 2015). Useful hot-water energy assumes water is heated from a 10°C cold-mains average to a 41°C shower delivery temperature, converted at 4.186 kJ/kg°C — this is then divided by your boiler/system efficiency (or heat pump COP) to give the energy actually purchased, since no heating system is 100% efficient. Carbon uses the UK Government (DESNZ) 2026 greenhouse gas conversion factors (gas 0.18231, electricity 0.13096 kgCO&sub2;e/kWh) applied to that purchased energy.

Your illustrative result

Estimated annual cost saving £0 water + energy, based on the figures entered

Water saved / year0 m³

Purchased energy saved / year0 kWh

Carbon saved / year0 kg CO&sub2;e

Showers / day (site)0

Water cost saving£0

Energy cost saving (gas)£0

Current vs new annual spend (water + energy)

Current spend£0

New spend£0

Turn this into asset value

A recurring annual saving like this can support a stronger business or property valuation.

Annual saving£0

Illustrative value supported*£0

*Illustrative only, using a 7× multiple as a starting point. Get a proper estimate, including a property-yield basis, with the Energy Value Calculator. Estimate your value uplift →

Where the numbers come from

The three things driving your result

This is an illustrative estimate, not a metered guarantee. It is most accurate where actual flow rates, usage patterns and utility rates are used rather than defaults.

Flow rate difference

The gap between your current and proposed flow rate, multiplied out across every shower, every use, every day of the year — this drives both the water and hot-water energy result equally. Default current flow (10 L/min) is a conservative planning figure producing an “up to 50%” saving; EU JRC’s published hotel guest-room model assumes 15 L/min for existing showers, available if that better reflects your site.

Heating & efficiency assumption

Only the water that needs heating carries an energy cost. We assume a 10°C cold-mains feed to a 41°C delivery temperature, then divide by your system’s efficiency (boiler, immersion, or heat pump COP) to get the energy actually purchased — not just the useful heat delivered.

Your own rates

Water, gas and electricity costs vary by contract and site. Swap in your actual billed rates for a result you can rely on rather than a generic estimate.

FROM WASTED FLOW TO MEASURED SAVING

Want this backed by a full site diagnostic?

Evolution NetZero can identify where water, energy and carbon are being wasted across your site — showers included — starting with a free, desktop-led report.

Get your Remote Energy Assessment Talk to us

Important limitations

This calculator provides an illustrative estimate only, based on typical assumptions and the figures you enter. It is not a metered measurement, an engineering survey or a guarantee of savings. Actual results depend on real usage patterns, existing pipework and heating system efficiency, water pressure, and site-specific factors. For a site-specific figure, use Evolution NetZero’s Remote Energy Assessment or a qualified engineer.