Pol 02 - NOx Emissions

Backup or emergency heating systems - KBCN0936

NOx calculations should be based on permanent heating systems and should not include backup systems used for maintenance or in emergencies. BREEAM assessments measure the as designed performance level of the building as it normally functions.

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CHP NOx emission conversion - KBCN0592

If the CHP manufacturer cannot provide the NOx emissions in mg/kWh it is not possible to award any credits. The CHP manufacturer must provide the NOx emissions in mg/kWh, the conversion factors provided in the Technical Manual can only be used for boilers.

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District heating systems - KBCN0979

District heating systems serving the assessed building must be assessed for NOx emissions.

• Where the developer has no choice over this connection, the maximum number of credits available for the asset type is awarded for this issue. For instance, the connection is mandated by a local authority or other statutory body.
• Where the developer has choice over their connection, the district heating system must be assessed against BREEAM criteria. This is regardless of any incentives to connect.

14-Dec-24 - Wording clarified.
07-Dec-17 - Reference to NOx emissions clarified

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District heating systems which off-set grid electricity - KBCN0857

District heating systems which incinerate waste usually have NOx emissions higher than the levels set to achieve any BREEAM credits. However, where a district heating system also generates electricity, this can be used to off-set NOx emissions from grid electricity. In such cases, the calculation methodology for CHP systems can be used to calculate NOx emissions for the district heating network.

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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.  

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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.  

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Grid NOx emission factors - KBCN0151

The Grid NOx emission factors should be compliant and relevant to the scheme of the development under assessment i.e. BREEAM NC 2011/ 2014 or BREEAM 2008. In the same way that we do not apply the more stringent requirements of some BREEAM NC 2011 / 2014 Issues retrospectively to 2008 schemes, for a BREEAM 2008 scheme, the emission figures stated in the relevant manual must be used.

09 Aug 2023 - Applicability to IRFO 2015 removed due to conflict with the guidance.

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Heat pumps powered by renewable energy - KBCN0422

Where renewable energy is used partially to offset grid electricity in heat pumps, this can contribute towards a reduction in equivalent NOx emissions. To account for seasonal variations in renewable energy generation, this must be calculated over the course of a year.

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Hot water supplied by grid electricity - KBCN0549

Where grid electricity is used to supply the hot water heating system, the NOx emissions will be the same as that stated in the guidance for any other heating systems.

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