What Is A Water Efficiency Calculation?

When building a property, there are a few features that must be surveyed to ensure the property passes regulations, one of which is water efficiency.  To assess the utilisation of water within the property a water efficiency calculation must be completed. 

But, what exactly is the water efficiency calculation? Each new property and some conversions will require a water efficiency calculation; this water calculation assists the building’s owners in calculating the estimated total water consumption consumed per person, per day.

Continue reading to learn more about this topic and what a water efficiency calculation is.

What Is A Water Efficiency Calculation?

Water efficiency is becoming an important factor in achieving sustainability. Each property will require a water efficiency calculation; this water calculation assists the building’s owners in calculating total water consumption consumed per person, per day.

Building Regulation 36(1) has defined requirements for each new build or conversion, demonstrating that all new build residences and those formed by change of use must meet Requirement G2 and Regulations 36 and 37 of the Part G Building Regulations.

Why Is Water Efficiency Calculation Important?

Water efficiency calculations are an important aspect of the design and construction process because they are an economical solution to improve water efficiency. Based on a water efficiency calculation, builders are able to install appliances and fittings that use water efficiently to negate the undue consumption of water

Additionally having a water efficiency estimate readily available then makes improvements to water usage easier, allowing you to efficiently reduce water consumption in your building.

When Do You Require A Water Efficiency Calculation 

Water calculations should ideally be conducted during the design stage to ensure that the fittings and appliances do not exceed the 125/100 litres/person/day limit. 

Before you can receive the completion certificate for your new home, you must submit a water efficiency calculation.

There is some wiggle room, however, as other authorities, typically in London and the surrounding areas, may set lower standards. Local rules must be always followed to ensure compliance. 

Water calculations are then revised at the end of the build before the final Part G water certificate is created and submitted to Building Control.

Who Carries Out A Water Efficiency Calculation

The water efficiency calculation is not something that is done after the construction phase; rather, it is completed by those engaged in the design and construction phase of the building, such as a developer or property manager.

How Is Water Efficiency Calculated In The UK? 

A water efficiency calculation measures the water usage of taps, toilets, showers, bathtubs, washing machines, and dishwashers to guarantee that the average water usage does not exceed 125/100 litres/person/day.

The water efficiency calculation is presented in the form of a table, which includes the fitting and appliance, as well as the flow rates/water usage. The total water consumption in litres per person per day will be recorded.

The calculation considers:

  • Taps (excluding kitchen & utility)
  • Kitchen and utility taps
  • WCs
  • Baths
  • Showers
  • Washing Machine
  • Dishwasher
  • Water Softener
  • Rain/Greywater collection & use

Water Efficiency Calculation In England 

Working with RS Energy gives you the assurance that your water efficiency calculation will proceed successfully. We will support and advise you from start to finish, delivering reports to meet Part G Building Control requirements.

If you’re building a new house, extension, or conversion, you’ll likely also need an SAP Calculation. RS Energy are SAP calculation and energy compliance experts. Get in touch with us today to see what you need for your building to ensure compliance.