This glossary defines the key terms, abbreviations, and technical concepts used throughout the Future Buildings Standard Guide. Each definition links to the relevant page where you can learn more.
- Building Emission Rate(BER)
- The calculated CO₂ emission rate of the actual building design, expressed in kgCO₂/m²/year. Must not exceed the Target Emission Rate (TER) for compliance.Learn more →
- Building Primary Energy Rate(BPER)
- The calculated primary energy consumption of the actual building design, expressed in kWh/m²/year. Must not exceed the Target Primary Energy Rate (TPER) for compliance.Learn more →
- Building Regulations UK Part L(BRUKL)
- The compliance report produced by SBEM or approved Dynamic Simulation software demonstrating that a non-domestic building meets Part L energy performance requirements. Required at both design stage and as-built.Learn more →
- Building Circular
- An official communication from MHCLG to local authorities and approved inspectors explaining how new building regulations should be implemented. Building Circular 01/2026 covers the Future Homes and Buildings Standards.
- Coefficient of Performance(COP)
- A measure of heat pump efficiency – the ratio of useful heating output to electrical energy input. The FBS notional building assumes a minimum COP for heating systems.Learn more →
- Dynamic Simulation Modelling(DSM)
- An alternative compliance route to SBEM for non-domestic buildings, using approved software (such as IES VE or TAS) to model building energy performance in detail. Required for buildings with complex HVAC systems.Learn more →
- Future Buildings Standard(FBS)
- The 2026 update to Part L Volume 2 of the Building Regulations, setting new energy performance requirements for non-domestic buildings in England. Enforced from March 2027 (non-HRB) or September 2027 (HRB).Learn more →
- Future Homes Standard(FHS)
- The 2026 update to Part L Volume 1 of the Building Regulations, setting new energy performance requirements for domestic buildings in England. The domestic equivalent of the FBS.Learn more →
- Higher-Risk Building(HRB)
- A building at least 18 metres tall or with at least 7 storeys, containing at least 2 residential units. HRBs have a later FBS enforcement date (September 2027) and are regulated by the Building Safety Regulator.Learn more →
- iSBEM
- The government’s free interface software for the Simplified Building Energy Model (SBEM). Used to produce BRUKL compliance reports for straightforward non-domestic buildings.Learn more →
- National Calculation Methodology(NCM)
- The approved methodology for calculating the energy performance of non-domestic buildings in England and Wales. SBEM and approved Dynamic Simulation tools both implement the NCM.Learn more →
- Non-Domestic Energy Assessor(NDEA)
- A qualified professional authorised to produce Energy Performance Certificates and BRUKL reports for non-domestic buildings. Levels range from L3 (simple buildings) to L5 (complex buildings with DSM).Learn more →
- Notional Building
- A theoretical reference building of the same size, shape, and use as the actual building but with standardised construction specifications. The Target Emission Rate and Target Primary Energy Rate are derived from the notional building.Learn more →
- Part F
- The section of the Building Regulations covering ventilation requirements. Part F Volume 2 applies to non-domestic buildings and works alongside Part L to ensure adequate indoor air quality.
- Part L
- The section of the Building Regulations covering conservation of fuel and power. Part L Volume 2 covers non-domestic buildings. The 2026 edition implements the Future Buildings Standard.Learn more →
- Part O
- The section of the Building Regulations covering overheating mitigation in new residential buildings. While primarily domestic, Part O principles inform non-domestic design in mixed-use developments.
- Simplified Building Energy Model(SBEM)
- The government’s calculation tool for assessing the energy performance of non-domestic buildings. SBEM implements the National Calculation Methodology and is used to produce BRUKL compliance reports.Learn more →
- Target Emission Rate(TER)
- The maximum allowable CO₂ emission rate for a building, derived from the notional building specification. The actual Building Emission Rate (BER) must not exceed the TER.Learn more →
- Target Primary Energy Rate(TPER)
- The maximum allowable primary energy rate for a building, derived from the notional building specification. The actual Building Primary Energy Rate (BPER) must not exceed the TPER.Learn more →
- U-value
- A measure of thermal transmittance – how much heat passes through a building element per unit area per degree of temperature difference, expressed in W/m²K. Lower U-values indicate better insulation.Learn more →
Frequently Asked Questions
What does BRUKL stand for?
BRUKL stands for Building Regulations UK Part L. It is the compliance report produced by SBEM or approved Dynamic Simulation software demonstrating that a non-domestic building meets Part L energy performance requirements. A BRUKL report is required at both design stage and as-built.
What is the difference between BER and TER?
BER (Building Emission Rate) is the calculated CO2 emission rate of the actual building design. TER (Target Emission Rate) is the maximum allowable CO2 emission rate, derived from the notional building specification. For compliance, the BER must not exceed the TER.