Version 1 · Launched March 2026
Twin & Earth · UK NZCBS Guidance

The UK's first unified net zero buildings standard.

A practical guide for consultants, developers, and asset managers navigating NZCBS compliance — from brief through to verification.

13
Building sectors covered
11
Submission requirements
12mo
In-use data required for verification

What the Standard requires

To achieve Net Zero Carbon Aligned status, a building must satisfy all mandatory compliance metrics — measured on real in-use performance, not design-stage modelling.

Embodied Carbon

Fixed upfront carbon budgets per sector, varying by year of commencement. Must be calculated at design stage and confirmed as-built using RICS methodology.

Operational Energy

Sector-specific Energy Use Intensity (EUI) targets covering all energy loads including unregulated uses. Verified against 12 months of metered in-use data.

Renewable Generation — kWh/m²

On-site renewable generation targets (kWh/m² building footprint/year) set by UK location. The limits differ based on the asset and where it is; Scotland, Middle/North England, South England.

Renewable Generation — kgCO₂e/kWp

Alongside energy generation targets there are limits on the embodied carbon of renewable systems, set at 1,000 kgCO₂e/kWp for solar PV. For wind and hydroelectric generation there is no limit.

Refrigerants

The global warming potential of refrigerants within all in-scope systems is assessed and reported. The GWP limit for refrigerants is set at 677 kgCO₂e/kg where a refrigerant charge ≥ 3,000 kgCO₂e applies.

Fossil Fuel Free

No gas boilers. No on-site combustion of fossil fuels. All heating and hot water must be delivered through low-carbon technologies such as heat pumps.

District Heating and/or Cooling Networks

Buildings connected to district heating/cooling networks must comply with carbon content limits (kgCO₂e/kWh), and report energy used (kWh/m²/yr) and carbon emissions (kgCO₂e) for heat and coolth supplied.

Space Heating and Cooling

For all building types, annual space heating and cooling (kWh/m² GIA/year) and peak energy delivered for heating and cooling (W/m² GIA) must be reported. Specific limits apply to some asset types.

Required reporting — limits coming

These metrics have reporting requirements now but no numerical limits yet. The Standard indicates limits will be introduced in future versions.

Life Cycle Carbon

There are currently no limits on Life Cycle Carbon within the Standard — reporting only. Plans are in place to introduce limits as methodologies and data mature.

Operational Water Use

Minimum reporting requirements apply from an operational perspective. The Standard aims to bring forward numerical limits for operational water use in future versions.

Electricity Demand Management

Buildings over 500m² GIA are required to report electricity demand management. Limits are not yet set but are planned for inclusion in future versions of the Standard.

Carbon Offsetting

Not a requirement, but where a building seeks to report carbon offsetting there are minimum requirements to comply with within the Standard in order to claim conformity.

When to act across RIBA stages

Compliance decisions made late are expensive. Here's where NZCBS work belongs in your project programme.

0–1

Strategic Brief

Establish NZCBS ambition, sector targets, and client mandate

2

Concept Design

Optioneering against EUI limits; early embodied carbon assessment

3–4

Developed Design

Confirm fossil-fuel-free strategy; fix structural and facade carbon budgets

5–6

Construction

As-built embodied carbon; on-track check at practical completion

7+

Verification

12 months metered data → submit to Bureau Veritas for NZC Aligned status

Sector Limits & Targets

Select your sector, subsector and project parameters to view the applicable NZCBS Annex A limits.

Sector
Subsector / Type
Works Type
Commencement Year
Location (Renewables)

Readiness Check

Answer 6 quick questions to understand where your project or organisation currently stands against the NZCBS.

Question 1 of 6