New Construction / UK / 2018 /

09 Pollution

Information correct as of 25thJuly 2024. Please see for the latest compliance information.

Brownfield sites – achieving the greenfield rate of run-off for the 1-year and 100-year return period events - KBCN1450

For a brownfield site that has achieved the greenfield rate of run-off for the 1-year and 100-year return period events, criterion 6 can be deemed to be met.

Calculation of greenfield run-off rates - KBCN1352

The calculation of greenfield run-off rates must be in accordance with IH Report 124, Flood estimation for small catchments. Reference to the Flood Estimation Handbook can be made, but only where this is considered appropriate. This is only applicable to v3.0 of the UK NC 2018 technical manual and will be clarified in the next re-issue.

Campus with multiple building assessments - KBCN0597

If a campus development project has multiple building assessments being built in conjunction with each other, each building should be assessed independently.  Where there are noise sensitive buildings; including any new buildings in the process of being built, the criteria requirements must still be met.

District cooling – Used in combination with local cooling - KBCN1634

Where district cooling can be considered outside the scope of the assessment, either in accordance with the Methodology section of the technical manual or in line with KBCN0759, compliance must be based on calculating the DELC for all systems. However, where the district cooling system is exempt from assessment, as described above, this should be based on a GWP of zero for the district cooling system.

Emissions – measuring heating demand - KBCN0182

Emissions for all heat sources should be measured under normal operating conditions which are when all heat sources from the building plant are operating to their maximum design heat outputs to meet the building's heating demands. Where plant is designed to operate below maximum capacity, for example multiple or modular systems or standby boilers,the emissions should still be calculated for the plant operating to meet the building’s heating demand. Any redundant capacity or standby plant should not be included.  

Erratum – UK NC2018 Pol 03 – Peak rate of run-off for greenfield sites - KBCN1063

The 30% improvement on the peak rate of run-off, required under criterion 6, is only applicable to Brownfield sites.  Post-development, Greenfield sites are only required to achieve a peak rate of run-off that is no greater than the pre-developed site. The 2014 UK NC scheme required both Greenfield and Brownfield sites to not increase the peak rate of run-off as a result of the development.  A 30% improvement for brownfield sites is in keeping with BREEAM's aim to continue to drive improvements and mitigate the impacts of development.
10/08/18 - Technical manual updated. Only relevant to v1.0 of the manual

Erratum – UK NC2018 Pol 03 – Prerequisite for Simple buildings assessments - KBCN1067

The prerequisite requiring the appointment of an appropriate consultant is applicable to Simple buildings assessments for the Flood resilience and Minimising watercourse pollution credits. The prerequisite must also be met if the two credits and exemplary credit are awarded for Simple Buildings achieving compliance to the Surface Water Run-off criteria. Refer to the text under 'Up to two credits - Simple Buildings - Surface water run-off'. The prerequisite does not, however, apply to the 'Simple buildings only' criteria 24-25. Assessment scope for a Simple building:      

Extensions – Retaining existing heating plant - KBCN0336

When assessing an extension where existing heating plant is retained, the current emissions output should be used to determine compliance. The emissions should not be taken from the original manufacturers information at the time of installation.  

Extensions and infill developments - KBCN1055

When assessing a new extension or infill development on an existing site, only new lighting specified as part of the assessed works needs to be considered.

External lighting inside wider building - KBCN0906

Where a building undergoing assessment is located inside of another building, for example a retail unit within a shopping centre, Ene 03 External lighting and Pol 04 Reduction of night time light pollution should be assessed as follows; Ene 03 'External lighting' that is inside of the wider building, using the example above the lighting is external of the retail unit itself but inside of the wider shopping centre, criteria relating to the luminous efficacy should be applied as presented within the manual. For the criteria relating to controlled for prevention of operation during daylight hours and presence detection in areas of intermittent pedestrian traffic, however, instead of demonstrating that the lighting is not operational during daylight hours, it should be demonstrated that the lighting is not operational outside of the operational hours of the wider shopping centre. Any external lighting within the scope of works being assessed that is located outside of the wider shopping centre, for example if the retail unit had an entrance or exit that leads on to the street outside, this would need to be assessed against the criteria presented within the manual. Pol 04 If the building undergoing assessment has no external lighting that is outside of the wider building, it can be considered that the building has no external lighting. However, as above, any external lighting within the scope of works of the assessment that is located outside of the wider building will need to be assessed as the criteria is presented within the manual.
10/05/2019 Reference to specific criteria numbers removed and made applicable to UK NC2018

Flood Resilience - KBCN1478

In order to award two credits
  1. Flood risk must be determined by a compliant, site-specific Flood Risk Assessment and cannot be based solely on on EA Flood Maps
  2. The credits for flood risk are awarded based on the pre-development site
Sites which have a medium or high flood risk from one or more sources (pre-development) can only achieve one credit, subject to mitigation measures being implemented as part of the development. The criteria seek to encourage the development of sites in areas of low flood risk from all sources.
01/11/2021 Clarified: 'Sites which have a medium or high flood risk from one or more sources...'

Flood resilience – appropriate consultant - KBCN1453

Where compliance is only sought for criteria 2-4a, if the assessor is satisfied and can justify that the person conducting a flood risk assessment for the development has the appropriate level of knowledge to undertake it, then they do not need to meet the full definition of the 'appropriate consultant'.

Flood resilience – Pre-existing flood defences - KBCN1021

In an area protected by existing flood defences, (designed to withstand a certain magnitude of flooding), the appropriate number of flood risk credits can be awarded where the defences reduce the risk to ‘low’ or ‘medium’ and the following conditions are met: 1. The development is not located in an area where new flood defences have to be, or have been, constructed to minimise the risk of flooding to the site and its locality purely for the purpose of the development or its wider master plan. 2.The development is located on previously occupied land (as defined by the criteria in BREEAM issue LE 01 Site selection). 3.The relevant agency confirms that, as a result of such defences, the risk of a flood event occurring is reduced to low or medium risk. If firm confirmation is not provided then the credit cannot be awarded. A statutory body’s local or regional office may be able to provide more information on existing defences in the area in which the assessed development is located.

Flood resilience – Third party feature acting as flood defences - KBCN1022

There are many landscape feature defences, owned by third parties, which due to their location act as a flood defence by default, e.g. motorway, railway embankments, walls etc. It can be assumed that such embankments will remain in place for the lifetime of the development, unless the assessor or project team have reason to believe otherwise. For walls, assurance must be sought that the wall is likely to remain for the design life of the building.

Flood risk – Site situated across numerous flood zones - KBCN0532

Where a site is situated across more than one flood zone, the flood zone with the highest probability of flooding, i.e. the worst case scenario, must be considered for the purpose of the BREEAM assessment. An exception to this would be where the areas in the higher probability zone include only soft landscaping and it can be demonstrated that access to the building will be maintained in a flooding event. This is to ensure that the site has adequately managed the worst case scenario level of flood risk associated with the site's location. 
22/07/2022 Applicability to HQM One confirmed
07/03/2018 Updated to include circumstances where an exception may apply.

Flush stud lighting - KBCN1028

Flush stud lights used for safety purposes in vehicle manoeuvring areas may be excluded from the assessment.

Freestanding commercial fridges and freezers - KBCN0577

Freestanding commercial fridges and freezers must be included in the assessment of the Pol 01 issue, even when they are not connected to the building cooling system. Only domestic white goods are excluded from the assessment of this issue.

GN38 Relating drainage reports to BREEAM UK NC 2018 - KBCN1564

Latest version: v1.2, January 2023 Guidance Note 38 (GN38) has been produced to help assist BREEAM Assessors relate the contents of drainage reports to the ‘Surface water run-off’ and ‘Minimising watercourse pollution’ criteria in Pol 03 for BREEAM UK New Construction 2018 and BREEAM UK New Construction Version 6. The guidance note does not cover the criteria for ‘Flood resilience’. Completing the template is optional. It is an aid for demonstrating compliance and not a requirement. A separate guidance note exists for BREEAM UK New Construction 2014 (see GN15). Download Guidance Note 38 View all Guidance Notes on BREEAM Projects (licensed assessors only)
31-Jan-2023 – Release of GN38 1.2. Fixes issue with incorrectly linked inputs (8c and 10a).

Greenfield/Brownfield site – Definition - KBCN1259

For the purposes of this Issue, the following definitions apply: Greenfield site A site which has never been built on, includes minimal development or which has been substantially cleared of all buildings and associated fixed surface infrastructure* and has subsequently remained undisturbed for five years or more. * Typically, the site includes less than 5% residual development by area. This supersedes the definition of 'Greenfield' for this Issue in the technical manual. Brownfield site Any site which does not fall within the above definition of 'Greenfield site'  

ILP Guidance Note 1 updated - KBCN1385

Pol 04 references the ILP Guidance notes for the reduction of obtrusive light 2011. This has now been updated to the ILP Guidance note 1 for the reduction of obtrusive light 2021. This is available for free from the ILP website. Requirements Table 2 of the guidance note classifies different lighting environments into Zones E0 to E4. Use this table to define which sets of requirements apply to the assessment. Tables 3-8 of the guidance note define the requirements for criterion 2. For cut-off type luminaires which (by design) block out light in obstructive directions, calculations are not required for meeting requirements relating to: This update will be reflected in the future revisions of the relevant manuals.
02-Nov-2021 Applicability to all UK BREEAM schemes confirmed.
27-Sep-2023 Updated for ILP Guidance Note 1 2021. Requirements clarified. Scheme applicability updated.

Impact of refrigerant – Refrigerants with low GWP - KBCN1472

Where systems only use refrigerants with GWP ≤ 10 The Pol 01 calculator does not have to be completed. Providing evidence of the compliant systems and refrigerants used is enough to award maximum credits for impact of refrigerant. Mix of systems with GWPs below and above 10 The Pol 01 calculator does have to be completed. The calculator must include systems with GWP ≤ 10 to ensure credits are based on the average value across all systems.
20-Dec-2023 Updated to include scenarios where there is a mix of systems with GWP above and below 10.

Leak detection system based on pressure changes - KBCN0326

A system that uses pressure changes to detect leaks is not necessarily compliant. To be deemed compliant the leak detection system would need to monitor the refrigerant pressure and the operating conditions to address the problem of natural fluctuation.

LZC technologies – energy centre or other LZCs connected at a later stage - KBCN0267

If a project specifies LZCs that have been proposed in the feasibility report which reduce emissions, and/or will be connected to a site-wide energy centre operational at a later stage of the phased development, after the Post Construction Stage review has been submitted, the Energy and Pollution issues can be assessed as follows: In a phased development where the primary heating system will be upgraded at a later stage than the building being assessed, a commitment to install the new heating source must be made in the General Contract Specification (as per the BREEAM requirements). BREEAM does not specify a particular time for phasing as it is difficult to set parameters, however as a rule building users should have to wait the least time possible before they can use the upgraded heating source. For the quality audit, two Energy model outputs/EPCs must be produced at the final stage - one with the actual interim system installed for building control, and one for the BREEAM assessment which can include the predicted energy from the proposed energy centre.  Additionally, the legally binding general contract specification for the new heating source must be submitted with details of the timescales proposed for the completion of the second phase of work. Where this approach is to be followed BREEAM must be consulted in each case to ensure that the arrangements are sufficiently robust to award the credits. BREEAM seeks to recognise the environmental impacts of a building's energy use throughout its life, therefore temporary arrangements can be accommodated, provided there is robust evidence on future connection to the permanent systems.
24/08/2022 - Applicability to UKNC V6 confirmed

Minimising water course pollution – no water courses present - KBCN0550

The credit for 'minimising water course pollution' has to be assessed even in cases where no water courses are in close vicinity to the site under assessment. This is because the aim of this credit is to encourage developments to minimise water course pollution by restricting the discharge of potentially contaminated water from entering the public sewer. Minimising water course pollution does not focus on water directly entering water courses.

Minimising watercourse pollution – end of pipe solutions - KBCN1025

End-of-pipe solutions, such as ponds and basins, will only be deemed to comply with the 5mm criteria where the principal run-off control, to prevent discharge from the first 5mm of a rainfall event, is achieved using source control and site control methods.

Minimising watercourse pollution – Extensions and infill developments - KBCN1027

When assessing an individual building on an existing site, i.e. infill development, the criteria apply to areas within the construction zone that present a risk of pollution as well as any areas outside the construction zone affected by the new works, eg. drainage onto or from the proposed development.

Minimising watercourse pollution – First 5mm of rainfall requirement - KBCN1059

It may not be possible for the first 5mm of rainfall to be prevented from leaving a site completely. An appropriately qualified professional must explain comprehensively why this criterion cannot be fully met and design a system to meet the intent of this criterion as far as possible. Where this can be justified and all other relevant criteria have been achieved, the credit can still be awarded.

Minimising watercourse pollution – Green roofs - KBCN1026

Rain that falls onto the surface of green roofs can contribute to this requirement. Evidence,however, still needs to demonstrate that the 5mm rainfall from all impermeable surfaces on-site is being dealt with.

No change in impermeable area - KBCN1273

The Methodology includes a section titled 'No change in impermeable area'.  Where this text is applied to a site, and the Surface Water Run-off - Rate credit is not targetted, criterion 5 is not applicable because no calculations or surface water design solutions are required. Note: the design for exceedance criterion (criterion 10) must still be demonstrated.

No external plant specified - KBCN0931

Where there is no external plant specified and the acoustician confirms that there is no significant noise source, it is acceptable for the acoustician to provide a formal statement in lieu of the noise impact assessment. All other evidence for this issue must be provided as listed in the Evidence table. The formal statement should be produced by a 'suitably qualified acoustician' (as defined in the Relevant Definitions for this issue) and should justify this approach with reference to the specific internal plant to be installed and the proximity of any noise sensitive areas or buildings. The statement must explain clearly how the aim of the issue is being met.

No refrigerant use – shell & core assessments - KBCN1058

The credits for Pol 01 can be awarded if the asset requires no refrigerants as per the criteria. In speculative assessments, future tenant systems are unknown. To award the credits, evidence must show that the asset has been designed to operate without the need for air-conditioning or comfort cooling for the conditioning of occupied spaces. One way to demonstrate this is to achieve the ‘Free cooling’ credit. Only refrigerants used for occupant comfort are assessed. Do not assess any refrigerant use for process-related functions.
21.09.2021 Wording amended for clarity

Not enough rows in the Pol 01 calculator - KBCN1274

If additional rows are required in the calculator, it is acceptable to add the specification of multiple models together in one tool, provided they are the same model and have all the same inputs for columns F to M. The weighting of the systems across the building is done by the System Capacity and Total Refrigerant Charge (columns E and F), so you would multiply each of these two figures by the total number of the system specified. This gives the contribution of the systems to the building's cooling capacity and charge. If further rows are still required please submit a query using the webform in BREEAM Projects, attaching a copy of the tool and specify the number of additional rows required.
08/10/21 link to webform added

NOx emissions – Units of measure - KBCN1393

For gas and oil appliances, NOx emissions should be measured on a dry basis at 0% excess oxygen, in accordance with the Ecodesign regulations.

Pol 02 benchmarks – Oil-fired boilers - KBCN1208

It has come to our attention that there is an error in Table 12.4 in Pol 02, relating to the NOx emission benchmarks for oil-fired boilers. The table below confirms the correct benchmarks.  
Appliance type and unit Fuel 1 credit (Low pollution location) 1 credit (High pollution location) 2 credits (Low pollution location) 2 credits (High pollution location)
Boiler (mg/kWh) Oil 56 73 56 55 67 50
This will be confirmed in the next re-issue of the technical manual, but can be applied immediately in all issues of the UK NC2018 scheme.

Pollution Prevention Guidance documents - KBCN1051

On 17 December 2015, the Pollution Prevention Guidance documents (PPGs) published by the Environment Agency were withdrawn. These can be found in the National Archives or on the Scottish Environment Protection Agency website where they are still current documents. Many BREEAM schemes and the Home Quality Mark refer to these PPG documents as they are still considered to be best practice even though they have been withdrawn. Projects should continue to use the PPGs referenced in the relevant manuals. BREEAM will continue to review this situation and provide an update as and when appropriate.
26 09 2018 Made applicable to Man 03 and Pol 03 in UK NC2018 and Man 03 in UK NC 2011, UK NC2014 and UKRFO 2014

Post construction noise level testing - KBCN00043

Noise level measurements do not need to be taken at the post construction stage if the acoustician has accurately modelled the noise level from the plant, using manufacturer's literature, and site measurements taken at the design stage. Any attenuation measures specified by the acoustician in their report must be confirmed as being present post construction. If the acoustician has been unable to model the noise level accurately, post construction measurements are needed to demonstrate compliance. Calculations and recommendations from the acoustician are relied on to be accurate and in keeping with best practice; attenuation measures are assumed to be specified and installed correctly.   

Reduction of night time light pollution – Night-time operation - KBCN0697

Note: This KBCN supersedes INC 2016/INC V6 Pol 04 CN3.1  During hours of operation between 23:00 and 07:00, lighting required for operational reasons does not have to be modified for BREEAM compliance. The aim of this Issue is to reduce light pollution by automatically switching off the external lighting or by complying with lower levels when the building is not in use.    
23 Jan 2023 - Note added to address conflict with INC Pol 04 CN3.1. KBCN title updated for consistency - The technical manual will be updated accordingly in the next re-issue
008 Mar 2018 Wording amended to add clarity.

Relating drainage reports to BREEAM – GN15 and GN38 - KBCN1169

Guidance Note 15 (GN15) and Guidance Note 38 (GN38) have been produced to help assist BREEAM Assessors relate the contents of drainage reports to the ‘Surface water run-off’ and ‘Minimising watercourse pollution’ criteria in Pol 03. They do not cover the criteria for the ‘Flood resilience’. We have published two separate Guidance Notes because there are small, but significant, differences between the criteria in the two schemes (UK NC 2014 and UK NC 2018). This means that the Guidance Notes are not interchangeable: Note: Completing either template is optional. They are aids for demonstrating compliance and are not a requirement.

Reversible heat pump (VRF) providing both heating and cooling - KBCN0735

Where a reversible heat pump, which provides heating and cooling on reverse cycle with heat recovery, is used, the cooling capacity only should be used for the Direct Effect Life Cycle CO2e emissions (DELC) calculation. The cooling capacity of heat humps is normally less than the heating capacity, so compliance against the criteria will be based on the more challenging DELC value calculated.

Safety and security lighting – definition - KBCN0888

BRE does not provide a specific definition of safety and security lighting, as this could vary, depending on the project and location of the lighting. Together with the design team, the assessor is required to determine which lights are provided purely for safety and security purposes and which should be considered as general lighting.

Scope of issue – clarification – fixed installations - KBCN1660

The scope of this issue covers noise from external building services (or 'fixed installations' as written in the manual) serving areas designed for human comfort. The noise impact assessment excludes:

Scope of the refrigerant leak detection system - KBCN0530

The refrigerant leak detection system is required to cover any part of the plant or pipework which contains refrigerant.
21/08/17 KBCN amended to include pipework containing refrigerant.

Security lighting - KBCN1029

Light fittings specified to comply with specific security standards, but which conflict with the BREEAM criteria, can be excluded from the assessment of this issue. The assessor must obtain evidence confirming the specific security standards and that they are applicable to the assessed development.

Suitably Qualified Acoustician – Associate membership of the Institute of Acoustics - KBCN00064

Associate membership of the Institute of Acoustics (IOA) can be considered to demonstrate that the individual is a member of an appropriate professional body. This supersedes previous guidance on this matter, which has been updated following confirmation from the IOA that ‘Associate members’ are bound by the same Members’ Code of Conduct as ‘Full members’.    
06/06/2022 - BRE stance on this has been revised - Title also updated for clarity
13/01/2020 Wording clarified and confirmed applicability to Issue Pol 05
06/01/2020 Clarification that this applies to BREEAM UK NC2018

Surface water run-off – Derelict sites - KBCN1024

If the site has been derelict for over five years, the appropriate consultant must assess the previous drainage network and make reasonable assumptions to establish probable flow rates and volumes. They should use best practice simulation modelling to determine the 1 year and 100 year peak flow rates at the relevant discharge points. A site visit prior to development will be required unless accurate data already exists from a previous survey. The resultant professional report can then be used to determine the pre-development volumes and rates of run-off. Without this professional input, the site must be deemed as greenfield pre-development, assuming Soil type 5 for the calculation of the pre-development site run-off.

Surface water run-off – discharge to a tidal estuary or the sea - KBCN1023

The peak rate of run-off and volume run-off criteria can be deemed to be met if the site discharges rainwater directly to a tidal estuary or the sea. The site run-off must discharge directly into the tidal estuary or the sea. Typically, drainage pipes would only carry run-off from the site and would not need to cross privately owned land outside the boundary of the development before reaching the sea. A definition of tidal estuary is in the technical manual.

Surface water run-off – Highways and impermeable areas - KBCN1035

Where new non-adoptable highways are built, all new impermeable surfaces must be included in the calculations to demonstrate compliance with the peak rate of run-off and volume of run-off criteria. Where buildings are built beside existing highways or where adoptable highways are built, the impermeable area of the highway does not need to be included in the calculations.

Temporary power solutions in noise impact assessments - KBCN0171

Plants such as standby generators that are only used temporarily are excluded from the noise impact assessment.

Untreated buildings - KBCN1030

Buildings designed to be untreated, i.e. where internal spaces will not be serviced by heating, ventilation or air-conditioning systems and therefore have no noise generating plant will not assess this issue. An example of such a building could be for industrial warehouse storage.

Verification of measurements undertaken by non-SQA - KBCN1661

It is acceptable for individuals who do not meet the BREEAM definition of a suitably qualified acoustician (SQA) for Pol 05 to undertake the testing for this issue, provided the measurements or calculations are verified by a SQA. The SQA must review the report and confirm in writing that they have found it to:
  1. Represent sound industry practice
  2. Be appropriate given the building being assessed and scope of works proposed
  3. Avoid invalid, biased and exaggerated recommendations
Additionally, written confirmation from the SQA how they comply with the definition of a SQA is required.

Watercourse pollution from indoor parking - KBCN0545

If the design team can demonstrate that there will be absolutely no run-off from the indoor parking then the intent of the credit will be met. However, such proof would also have to demonstrate that no hydrocarbon spillage from vehicles found its way into the watercourse/sewer. It is likely that there would be water ingress from outside or that internal parking areas would have drains fitted and be cleaned regularly. In such conditions, the criteria are still applicable. The intent of this criteria is to ensure no hydrocarbons run off to any watercourse.

[KBCN withdrawn] ~ Surface water run-off – Rainwater harvesting - KBCN1064

This KBCN has been withdrawn and is no longer valid. This is because the BS 8515 has been withdrawn and its replacement makes no reference to storm water control. 
KBCN withdrawn on 26/09/18:

BS 8515 Rainwater harvesting systems: Code of Practice, Annex A (236) must be followed where rainwater harvesting systems are relied upon for storm water control. To ensure flood risk is not increased if the rainwater harvesting system is, for some reason, unavailable, the exceedance flow route capacity provided in accordance with CIRIA report C635 should ignore the beneficial effect of the rainwater harvesting system.

Information correct as of 25thJuly 2024. Please see for the latest compliance information.