Posted by Rayan Azhari

The UK Net Zero Carbon Building Standard - Part 1: Requirements

As the UK’s pioneering Net Zero Carbon Building Standard moves into a pilot phase, we wanted to share some of the headlines and unresolved challenges.

The team at Verco is comfortable supporting clients with any aspect of the Standard. However, at this stage we recommend our rapid screening service to assess property or assets in advance of submitting into the pilot phase. Applications for this close on Friday 31st January.

The Standard outlines several mandatory requirements for building performance and construction quality, categorized as pass/fail requirements, and a number of additional reporting metrics.

1.1.1 Pass/Fail Metrics

Pass/fail metrics are mandatory assessments with associated numerical limits or targets. Buildings must meet these limits or targets to achieve verification under the Standard.

Embodied Carbon:

  • Upfront Carbon Limits: Defined for different building sectors and work types, these limits apply to emissions associated with construction products and processes up to practical completion. They have an incremental timeline to 2050. Life cycle embodied carbon limits (covering modules A-C) are planned for future versions of the Standard.

  • For example, for new commercial residential buildings, the upfront carbon limit for projects commencing in 2025 is 500 kgCO2e/m2 GIA. This limit decreases over time, reaching 45 kgCO2e/m2 GIA by 2050.

Operational Energy:

  • Energy Use Intensity (EUI) Limits: Set for 13 building sectors, with 34 additional sub-sectors, these limits consider both new and existing buildings. New buildings are subject to stricter limits than existing buildings.

  • For instance, a new office building must achieve an EUI of 65 kWh/m2 GIA/year or less, while an existing office building undergoing a "One-Go Retrofit" in 2025 must achieve a limit of 115 kWh/m2 GIA/year, decreasing to 40 kWh/m2 GIA/year by 2050.

  • Heating and Cooling Limits: The Standard includes limits for the annual space heating delivered to new buildings. Limits on annual space cooling and peak energy demand are planned for future versions.

  • On-site Renewable Electricity Generation Capacity Targets: These targets apply to the minimum on-site renewable electricity generation capacity, expressed in kWh/m2 of building footprint per year. They are set for single family homes and all other property types, and vary by geographic location to account for solar irradiance. There are various exclusion criteria for this target.

  • District Heating and Cooling Networks Carbon Content Limits: Intensity limits for heat/coolth supplied from district heating and cooling networks. Existing networks must transition to fossil-fuel-free heat/coolth by 2040, while new networks must be fossil-fuel-free from the outset.

  • Refrigerants: The Standard sets a Global Warming Potential (GWP) limit for refrigerant gases in each refrigerant system. This is currently set at 677 kgCO2e/kg, aligning with the GWP of R32. It is likely to decrease in future versions.

1.1.2 Pass/Fail Requirements are mandatory assessments of building performance with non-numerical criteria

  • Fossil Fuel Free: The Standard requires buildings to be fossil fuel free, with exceptions for specific circumstances, such as essential backup systems for data centres or critical infrastructure.

1.1.3 Reporting Metrics are mandatory assessments that do not have associated limits or targets in the current version of the Standard

  • Life Cycle Embodied Carbon: While upfront embodied carbon has limits, the Standard requires reporting of life cycle embodied carbon (modules A-C). This data will inform the development of future limits.

  • Operational Water Use: The Standard mandates reporting of annual operational water use and the associated carbon emissions.

  • Electricity Demand Management: The Standard requires reporting data related to electricity demand in kWh at specific percentiles (the 99th percentile of energy demand, the 50th percentile of energy demand, the 1st percentile of energy demand).

1.1.4 Additional Considerations

  • Pilot Testing is planned to run in early 2025 and will inform the final requirements and expectations of the Standard.

  • Verification: To demonstrate conformity with the standard, buildings must undergo third-party verification. The verification process is expected to be finalised and released soon.

1.1.5 Key Principles and Future Developments

The Standard is based on a "fabric first" approach, prioritising energy efficiency and demand reduction. It emphasises a whole-life carbon approach, considering both operational and embodied emissions.

The Standard is expected to evolve over time, incorporating:

  • life cycle embodied carbon limits

  • more comprehensive limits on heating and cooling demand;

  • limits for electricity demand management; and

  • a robust verification process.

The UK NZCBS provides a comprehensive framework for achieving net-zero carbon buildings in the UK, with mandatory requirements for performance and construction quality. Its data-driven approach and focus on continuous improvement will play a crucial role in decarbonising the built environment.

Do get in touch if you would like to discuss any of the points above further, or to run your buildings through Verco’s rapid screening service.

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