Commercial water efficiency calculations
Water consumption calculations for offices, retail, schools, healthcare, hotels and mixed-use schemes, including BREEAM Wat 01 support. Send us your drawings for a fixed-fee quote.
At a glance
Our free online calculator covers new homes under Part G. Commercial and non-domestic buildings work differently, so we handle them as a consultancy service. You send us the drawings and fittings schedule, and we prepare the water consumption calculations, advise on the specification and give you a clear report for your BREEAM assessor, planning officer or client.
Who needs a commercial water calculation?
- Projects with a BREEAM target. Many planning policies ask non-residential development to reach a BREEAM rating, and some set a minimum number of Wat 01 water credits. The London Plan, for example, asks for the BREEAM Excellent standard for the Wat 01 water category.
- BREEAM assessors who need the water consumption calculation and supporting fittings evidence for Wat 01.
- Developers and contractors of offices, shops, schools, healthcare buildings, hotels, student accommodation and industrial units who want to know which fittings will hit the target before they are ordered.
- Mixed-use schemes with homes above commercial space. The flats need Part G water calculations and the commercial floors are assessed separately. We can do both.
What is BREEAM Wat 01?
Wat 01 (water consumption) is the BREEAM issue that rewards buildings for using less potable water. The proposed sanitary fittings and appliances are compared against a baseline specification for that building type, and credits are awarded for the percentage reduction achieved. Higher BREEAM ratings carry a minimum number of Wat 01 credits, so getting the specification right early can protect the overall rating.
The fittings that matter most are usually WCs, urinals, wash-hand basin taps, showers and kitchenette taps, along with any rainwater or greywater recycling that supplies WCs and urinals.
What we provide
- A water consumption calculation for the proposed fittings, based on your building type and occupancy.
- Specification advice showing which changes gain the most credits for the least cost, for example flush volumes, tap flow rates or urinal controls.
- Comparison of options so you can see the effect of each change before committing.
- Part G water calculations and Building Control reports for any dwellings in the scheme.
- A clear summary your BREEAM assessor or planning officer can follow line by line.
What we need from you
- Floor plans or a schedule showing the sanitary fittings in each area.
- Product data for the fittings, such as flush volumes, flow rates and urinal controls, if they have been chosen.
- The building type and expected number of occupants or users.
- Details of any rainwater or greywater system.
- The target: the BREEAM rating or Wat 01 credits you need, or the wording of the planning condition.
How it works
- Send your drawings. Email the plans and any fittings information to us.
- Fixed-fee quote. We confirm the price before any work starts.
- Calculation and advice. We run the numbers and tell you what the specification achieves and how to improve it.
- Report. You receive a report ready to pass to your assessor, planning officer or client.
Price
Commercial calculations are quoted per project, because the work depends on the size and type of building. Single homes and housing developments can use our free water efficiency calculator, with reports from £20 + VAT on the pricing page.
Frequently asked questions
Does Part G water efficiency apply to commercial buildings?
No. The Part G limit of 125 or 110 litres per person per day only applies to new dwellings and dwellings formed by a change of use. Commercial buildings are usually assessed through BREEAM Wat 01 or a target set by planning or the client.
Can you help us gain more BREEAM Wat 01 credits?
Yes. We show which fittings make the biggest difference, such as lower flush volumes, flow-restricted taps and showers or urinal controls, so you can reach the credits you need without over-specifying.
Do you work with BREEAM assessors?
Yes. We provide the water consumption calculation and fittings evidence in a format your BREEAM assessor can review and use in their assessment.
Can you do mixed-use developments?
Yes. We prepare Part G calculations and Building Control reports for the homes and a separate water consumption calculation for the commercial areas.
How much does a commercial water calculation cost?
Commercial work is quoted per project. Send us the drawings and target and we will give you a fixed fee before any work starts.
Get a commercial water calculation quote
Email your drawings and the target you need to meet, or call us to talk it through.
Email for a quote Or call 024 7509 5700