|Number of credits available||Minimum standards|
To reduce the consumption of potable water for sanitary use in
The following is required to demonstrate compliance for:
|% improvement||No. of BREEAM credits|
Note: for some building types usage data may not be available. In such cases an alternative elemental based approach to compliance should be used to award credits (refer to Compliance notes and Additional Information section).
The BREEAM Wat 01 calculator defines the building types and activity areas for which the above components must be assessed.
Scope of the BREEAM Wat 01 Methodology for New Non Domestic Buildings. See criteria 1,2 & 3
The BREEAM Wat 01 calculator determines a figure for whole building water consumption from domestic scale components. This figure is derived using the actual component specification and default component usage factors for a range of building users/types.
The methodology is applicable to the majority of new non-domestic building types assessed using this BREEAM Scheme. There may however be some instances in which data on the usage patterns for certain types of buildings/users, are not available (or those used in the methodology are not appropriate).
Where this is the case, it will not be possible to calculate the whole building water consumption and percentage improvement level. In such instances, compliance and the number of credits achieved will need to be assessed using an alternative, elemental approach i.e. comparing the buildings component specification with minimum levels of performance and awarding BREEAM credits accordingly.
Details of the alternative approach and how to apply it are provided in the Additional Information section for this issue (see below).
Please also refer to the Compliance note below where the building is a mixture of different building types covered by the Water Efficiency Methodology.
Water consumption figures will need to be collected from manufacturers’ product information to determine the consumption of each type and specification of
WCs: actual maximum or, where dual flush, effective flush volume in litres/use
Urinals: Flush volume in litres/use for single use flush urinals. For cistern fed systems, the flushing frequency/hour and cistern capacity in litres.
Taps: Flow rate of each tap, at full flow rate in litres per minute measured at a dynamic pressure of 3±0.2 bar (0.3±0.02 MPa) for high pressure (Type 1) taps, or at a dynamic pressure of 0.1±0.02 bar (0.01±0.002 MPa) for low pressure (Type 2) taps (BS EN 200:2008, sanitary tapware, single taps and combination taps for supply systems of type 1 and 2. General technical specifications) including any reductions achieved with flow restrictions.
Showers: Flow rate of each shower at the outlet using cold water (T 30˚ C), in litres per minute measured at a dynamic pressure of 3±0.2 bar (0.3±0.02 MPa) for high pressure (Type 1) supply systems, or at a dynamic pressure of 0.1±0.05 bar (0.01±0.005 MPa) for low pressure (Type 2) supply systems (BS EN 1112:2008, Sanitary tapware. Shower outlets for sanitary tapware for water supply systems type 1 and 2. General technical specifications).
Kitchen taps: Maximum flow rate litres/min.
Baths: capacity to overflow in litres. Taps on baths should not be included in the calculation, as the water consumption from bath taps is taken account of in the use factor for baths. The calculation of water consumption for baths will assume 40% of the capacity to the overflow. This is to reflect that a) users tend not to fill the bath to overflow and b) the displacement affect the user has on the actual volume of water required for a bath.
Dishwasher: litres/cycle for domestic applications and/or appliances or litres/rack for commercial applications and/or appliances.
Washing machine: litres/use for domestic applications and/or appliances or litres/kg for commercial applications and/or appliances e.g. in hotels.
Waste disposal unit: flow rate in litres/minute.
|Greywater and rainwater system data. See criteria 4 & 5||
The following information is required where a greywater and/or rainwater system is specified:
Rainwater: in accordance with BS8515 ‘intermediate approach’ :
Rainwater: in accordance with BS8515:2009 Rainwater Harvesting Systems - Code of Practice ‘detailed approach’ :
Greywater: in accordance with BS8525-1:2010 Greywater Systems - Part 1 Code of Practice :
Where multiple fittings of the same component are specified, with various different flow rates, the flow rates for each type of fitting will need to be collected by the assessor and entered into the 'Average flow rate calculator worksheet' (contained within the Wat01 calculator) to determine the average flow rate for the component. This figure is then entered in to the relevant section of the Wat01 calculator.
|Using greywater and rainwater systems to off-set performance efficiency of components. See criteria 4 & 5||
Where greywater and/or rainwater systems are specified there is a minimum level of component efficiency that must be achieved to award 4 or 5 BREEAM credits and the exemplary level credit. This is to avoid awarding a higher number of BREEAM credits where performance from less efficient fittings is off-set by the specification of a greywater and/or rainwater collection system. The intention being to ensure demand reduction is prioritised before off-setting consumption.
Where a greywater/rainwater system is specified/installed, the component specification must achieve a percentage reduction in water consumption (over the baseline specification) equivalent to that required for 2 credits i.e. a 25% improvement.
Where this level is achieved, all of the total water demand met by greywater/rainwater sources can contribute to the overall percentage improvement required to achieve BREEAM credits. If it is not achieved, the percentage of greywater/rainwater allowable will be equivalent to the percentage improvement in water consumption achieved for the component specification (i.e. percentage improvement on baseline performance). For example, if only a 20% improvement is achieved, and therefore the building is not meeting the 25% requirement, then only 20% of the water demand met via greywater/rainwater sources can be used to off-set water consumption from the microcomponents.
This minimum requirement does not apply where only 1, 2 or 3 credits are sought or where no greywater/rainwater system is specified i.e. percentage improvement is based solely on the water efficiency of the microcomponent specification. BRE Global may allow some exemptions to this rule in instances where a particular fitting type requires a high flow rate due to specialised end-user requirements, and its specification prevents compliance with the 25% improvement level.
|Other permissible component demand for non potable water. See criteria 3,4 & 5||
The focus of this BREEAM issue is the performance of the building's permanent domestic scale water consuming components. Where a greywater or rainwater system is specified, the yield from the system should be prioritised for such uses i.e. WC/Urinal flushing. However, where the building demonstrates that it has other consistent (i.e. daily) and equivalent levels of non potable water demand, and such demands are intrinsic to the building’s operation, then it is permissible for the demand from these non domestic uses to be counted i.e. the demand for rainwater/greywater yield from such systems/components can be used as well as, or instead of non potable water demand from the buildings WC/Urinal components.
Examples of consistent and intrinsic demands could include laundry use in
|Other permissible source of non potable water. See criteria 3,4 & 5||The methodology allows for the collection and recycling of non potable water from the relevant components listed in the criteria i.e. taps, showers, baths and dishwashers/washing machines. In addition, where non potable water is collected from a non domestic component/source that is intrinsic to the building, then the amount collected can be accounted for in the methodology. This could include for example wastewater from active hygiene flushing, i.e. a regular hygiene flushing programme to minimize poor water quality in a potable cold or hot water system. In order for the method to account for this total, the design team will need to confirm to the assessor the yield from the component/system (in litres) and the frequency of that yield (in days) i.e. if once a week then frequency would be 7 days.|
|Building is a mixture of different functional areasSee criterion 1||
For the majority of buildings using the standard Wat 01, the BREEAM Wat 01 calculator defines the building type and range of different water consuming activity areas within that building; for example,
Determine the building’s total water consumption performance by carrying out separate assessments for each relevant activity area/building type. On completion of each assessment, the assessor will need to determine the percentage improvement as follows:
I = Overall improvement (%)
Where greywater/rainwater systems are specified, the assessor should take care to avoid unintended double counting of the yield from such systems and using it to off-set demand for each activity area/building type.
This compliance note is likely to become more relevant as the BREEAM Wat01 calculator develops to include more building types within the standard Wat01 method.
|Fixed water use. See criterion 6||The BREEAM water efficiency calculation includes an allowance for fixed water use. This includes water consumption for vessel filling (for building user drinking water), cleaning in kitchens and food preparation in buildings with a catering facility. Fixed uses are included to provide greater accuracy in reporting of the building’s overall estimated water consumption. As these uses are fixed for both the actual and baseline building models, their totals do not influence the achievement of BREEAM credits.|
If a water supply is provided to tenanted areas of the building, but sanitary components will be specified and fitted by future building tenants, then the following options are available to define the efficiency of flow rates for components in the shell only (tenanted) areas of the building:
Alternatively, fittings compliant with the BREEAM baseline level can be used for the purpose of determining the level of performance for the building (see Additional Information section for further detail on the baseline level).
|Components in healthcare facilities. See criterion 7||
In addition to meeting an overall percentage improvement level, the flushing control for each WC/urinal in a healthcare facility must be suitable for operation by patients with frail or infirm hands or activated by electronic sensors.
Components in clinical areas can be exempt from the calculation. For the purpose of this compliance note ‘clinical areas’ refers to all areas where a scrub-up trough, clinical sink or clinical basin is installed. This is not an exhaustive list and guidance should always be sought from the appropriate professional, such as a Health Authorities Infection control officer or a client infection control representative or equivalent, to ascertain areas of exemption specific to infection control and other considerations.
Although exempt, HTM07-04 contains guidance on water savings from medical related activities. Furthermore, in some cases, the use of water-efficient fittings and appliances may not be appropriate to the needs of the patient, and inappropriate specification may adversely affect the incidence and propagation of infections. In such instances, the assessor will need to confirm with BRE Global the exemption of components from the relevant building areas. The design team should also consult NHS guidelines concerning appropriate selection of sanitary fittings and fixtures and the control of legionella..
|Components in prison cells on HM Prison developments. See criterion 7||
In addition to meeting an overall percentage improvement level, the following requirements apply:
Where sanitary components are specified within a prison cell, a volume controller must be specified on the individual fittings or water supply to each cell.
A volume controller is an automatic control device to turn off the water supply once the maximum preset volume is reached within a defined period.
|Multi-residential developments with CSH assessed dwellings. See criterion 1||The number of credits achieved for Wat 1 of a Code for Sustainable Homes assessment cannot be directly used for this issue due to the differences in the calculation methodology.|
|No fittings present||
Where a project under assessment contains none of the specified components, the performance specification for components provided in facilities in an adjacent and accessible building must be used in the calculation, i.e. those facilities most likely to be used by the occupants and visitors of the assessed building.
This rule also applies where a project under assessment consists solely of an extension to an existing building, i.e. where the extended building contains no new sanitary facilities because there are facilities present within the existing building.
Completed copy of the BREEAM Wat 01 calculator
Relevant section/clauses of the building specification/ design drawings confirming technical details of;
OR where detailed documentary evidence is not available at this stage;
Completed BREEAM Wat 01 calculator
A letter of instruction to a contractor/supplier or a formal letter from the developer giving a specific undertaking, providing sufficient information to allow the water calculations to be completed.
Where Post Construction Stage assessment only, provide a completed copy of the BREEAM Wat 01 calculator and detailed documentary evidence (as listed for Design Stage) representing the building as built OR
Written confirmation from the developer that the appliances/fittings have been installed as specified for the Design Stage or Assessor site inspection report and photographic evidence confirming installation of components in accordance with a compliant specification OR
Where only a letter of instruction was provided with calculations at Design Stage, provide revised calculations and detailed documentary evidence (as listed for Design Stage) representing the building as built OR
Where different from Design Stage, provide revised BREEAM Wat 01 calculator and detailed documentary evidence (as listed for Design Stage) representing the building as built.
Table - 17 outlines the standards, by component type, used to define the performance levels set in BREEAM. These defined levels of efficiency have been steered by a range of published sources of information (see references4AECB Water Standards: Delivering buildings with excellent water and energy performance, vol 2 The water standards, technical background report (version 1), Grant, Thorton, AECB, 2009.BNWAT22: Domestic water consumption in domestic and non-domestic properties (version 1.1). Market Transformation Programme, 2007.BNWAT07: Baths - water efficiency performance tests (version 2.0). Market Transformation Programme, 2007.BNWAT23: Reliability of information on water consumption of appliances (version 1), Market Transformation Programme, 2007.BS6465-3:2006, Sanitary installations – Part 3: Code of practice for the selection, installation and maintenance of sanitary and associated appliances. BSi, 2006.CIRIA W10, Key Performance Indicators for water use in hotel, Rachel Waggett and Catherine Arotsky, CIRIA, 2006.CIRIA W11, Key Performance Indicators for water use in offices, Waggett, Arotsky, CIRIA, 2006.Conserving water in buildings, a practical guide. Environment Agency, 2007.Enhanced Capital Allowance Water Technology List criteria: www.eca-water.gov.ukReport by Entec UK Ltd for CLG: Research to Assess the Costs and Benefits of Improvements to the Water Efficiency of New Non-household Buildings, Final Report, Oct 2009.SD129: Certification and Listing of Low Flush WC appliances. BRE Global, 2008.SD174: Certification and Listing of Water Efficient Terminal Fittings. BRE Global, 2008.SD175: Certification and Listing of Water Efficient Baths. BRE Global, 2008.The Building Regulations 2000, Part G: Sanitation, hot water safety and water efficiency (2010 edition). HM Government.Waterwise: www.waterwise.org.ukWater Efficiency Calculator for New Dwellings. Communities and Local Government, 2009.Water efficient product labelling scheme: www.water-efficiencylabel.org.ukWater Supply (water fittings) Regulations 1999, DEFRA.Sustainable Products 2006: Policy Analysis and Projections, Market Transformation Programme, 2006.Water UK - Macerators, the impact on sewers: www.water.org.uk/home/policy/positions/waste-macerators-position-paperWater Efficient Buildings, water and planning, guidance for planners http://www.water-efficient-buildings.org.uk/) and therefore reflect robust levels of typical, good, best and exemplary practice.
|WC||6||5||4.5||4||3.75||3||Effective flush volume (litres)|
|Wash hand basin taps||12||9||7.50||4.50||3.75||3||litres/min|
(2 or more urinals)
(1 urinal only)
|Greywater/rainwater system||0%||0%||0%||25%||50%||75%||% of WC/urinal flushing demand met using recycled non potable water|
restaurant (pre-rinse nozzles only)
|Domestic sized dishwashers||17||13||13||12||11||10||litres/cycle|
|Domestic sized washing machines||90||60||50||40||35||30||litres/use|
|Waste disposal unit||17||17||0||0||0||0||litres/min|
|Commercial sized dishwashers||8||7||6||5||4||3||litres/rack|
Industrial sized washing machines
Please note that specifying components for a building in accordance with the above levels will result, in most cases, in the corresponding number of BREEAM credits being achieved. However, please bear in mind that the component specifications above are thresholds between each level. Therefore caution should be taken when defining a component specification for a BREEAM assessed building using exactly the same levels as the threshold levels. It is recommended that, where Wat 01 BREEAM credits are being targeted, the performance of a particular building’s component specification is verified using the BREEAM Wat 01 calculator before committing to a particular specification and ordering/installing components. This will provide greater assurance that the component specification achieves the targeted number of BREEAM credits.
As the methodology and BREEAM credits for water efficiency compare the buildings modelled water consumption performance against the performance of a baseline specification for the same component types, where a component type is not specified it is not accounted for in the methodology i.e. the component is excluded from both the proposed and baseline building. Therefore no benefit is gained in terms of BREEAM performance, which is the % improvement over the baseline building, by deciding not to specify a particular component. However, the methodology will reflect the reduction in overall water consumption (litres/person/day) for the building, as a result of not specifying a particular component.
A non domestic building’s water-efficient performance is determined using the BREEAM Wat 01
The baseline component specification is equivalent to the water efficiency of industry standard components (see Table - 17), steered by the minimum levels required by
The standard approach is the default method for calculating water efficiency of a BREEAM assessed building and is that used for most of the common building types, where usage data is available. For buildings types where usage data is not available, and therefore the standard approach of determining performance cannot be used, an alternative approach to compliance must be used (described below). Refer to the BREEAM Wat 01 calculator for the current list of building types which can be assessed using the standard approach.
Where it is not possible to use the standard approach to determine the buildings water consumption total (litres/person/day)the assessment can be completed on an elemental basis, as follows:
|Greywater/rainwater level achieved|
|Overall Component level||-||4||5|
|Baseline||0 credits||1 credit||2 credits|
|Level 1||1 credit||2 credits||3 credits|
|Level 2||2 credits||3 credits||4 credits|
|Level 3 or 4||3 credits||4 credits||5 credits|
|Level 5||4 credits||5 credits|
Please note: Whilst attempts have been made to align the benchmarking of both methodologies described above, they do determine performance in different ways. The number of BREEAM credits awarded by each method may therefore differ for the same water component specification. It is important to be aware of this difference when applying BREEAM New Construction to a number of different building types that form a part of the same overall development.
Product certification schemes provide specifiers and clients with greater assurance of manufacturers’ claims regarding the water efficiency performance of their products and therefore the potential water savings of different products. Specifying water efficient fittings certified by accredited bodies are encouraged by BREEAM, but at present the scheme does not require components to meet an approved standard to gain BREEAM credits.