Building primary energy rate
Approved document L, Conservation of Fuel and Power, Volume 2: Buildings other than dwellings, 2021 edition incorporating 2023 amendments, defines building primary energy rate (BPER) as: ‘Expressed as kWhPE/(m^2.year) and determined using the approved methodology.’
It is a metric used in the UK to assess the energy performance of a building as part of compliance with Building Regulations, particularly under Part L, which deals with the conservation of fuel and power. It was introduced as part of the 2021 changes to Part L, aligning with the UK's adoption of the EU Energy Performance of Buildings Directive (EPBD) and its focus on primary energy as a key performance indicator.
The BPER:
- Encourages the use of energy-efficient building designs.
- Incentivises low-carbon and renewable energy sources.
- Supports the UK's commitment to reducing carbon emissions and achieving net-zero goals.
The BPER quantifies the primary energy consumption of a building in kilowatt-hours per square meter per year over its expected use. It includes energy used for heating, cooling, hot water, lighting, and ventilation, as well as losses in energy generation, transmission, and distribution.
Primary energy refers to the total energy required to deliver usable energy to the building, including:
- Energy consumed on-site.
- Energy losses during generation (e.g., at a power plant).
- Energy losses during transmission and distribution.
To calculate BPER, the energy demand of the building is modelled using a standard methodology, typically the Standard Assessment Procedure (SAP) for dwellings or the Simplified Building Energy Model (SBEM) for non-dwellings. The energy is multiplied by primary energy factors (PEFs), which reflect the upstream energy losses. These factors depend on the type of energy source (e.g., electricity, natural gas, oil).
Approved Document L specifies that a new building’s BPER must not exceed a defined target primary energy rate (TPER). The TPER is a benchmark based on a notional building of the same type, designed to ensure new buildings achieve a minimum standard of energy efficiency.
[edit] Related articles on Designing Buildings
Featured articles and news
Boiler Upgrade Scheme and certifications consultation
Summary of government consultation which closes 11 June 2025.
Deputy editor of AT, Tim Fraser, discusses the newly formed society with its current chair, Chris Halligan MCIAT.
Barratt Lo-E passivhaus standard homes planned enmasse
With an initial 728 Lo-E homes across two sites and many more planned for the future.
Government urged to uphold Warm Homes commitment
ECA and industry bodies write to Government concerning its 13.2 billion Warm Homes manifesto commitment.
Places of Worship in Britain and Ireland, 1929-1990. Book review.
The emancipation of women in art.
CIOB Construction Manager of the Year 2025
Just one of the winners at the CIOB Awards 2025.
Call for independent National Grenfell oversight mechanism
MHCLG share findings of Building Safety Inquiry in letter to Secretary of State and Minister for Building Safety.
The Architectural Technology Awards
AT Awards now open for this the sixth decade of CIAT.
50th Golden anniversary ECA Edmundson awards
Deadline for submissions Friday 30 May 2025.
The benefits of precast, off-site foundation systems
Top ten benefits of this notable innovation.
Encouraging individuals to take action saving water at home, work, and in their communities.
Takes a community to support mental health and wellbeing
The why of becoming a Mental Health Instructor explained.
Mental health awareness week 13-18 May
The theme is communities, they can provide a sense of belonging, safety, support in hard times, and a sense purpose.
Mental health support on the rise but workers still struggling
CIOB Understanding Mental Health in the Built Environment 2025 shows.
Design and construction material libraries
Material, sample, product or detail libraries a key component of any architectural design practice.
Construction Products Reform Green Paper and Consultation
Still time to respond as consultation closes on 21 May 2025.
Resilient façade systems for smog reduction in Shanghai
A technical approach using computer simulation and analysis of solar radiation, wind patterns, and ventilation.