U-value conventions in practice: Worked examples using BR 443
BRE (Building Research Establishment) is an independent, research-based consultancy, testing and training organisation, operating in the built environment and associated industries.
U-value conventions in practice: Worked examples using BR 443 was written by Sean Doran and published by BRE on 13 Jan 2012. The 36 page publication helps designers develop a better understanding of how to calculate U-values and kappa-values for use in calculation tools. See also Conventions for U-value calculations (2006 edition) BR 443.
U-values, (sometimes referred to as thermal transmittances) measured in W/m²K represent how effective elements of a buildings fabric are as insulators. That is, how effective they are at preventing heat from transmitting between the inside and outside of a building. The lower the U-value of an element of a building's fabric, the more slowly heat is able to transmit through it, and so the better it performs as an insulator.
Kappa values (sometimes referred to as thermal mass values) measured in kJ/m2K represent the heat capacity per square metre of a material. This is used to quantify the thermal mass of building elements such as walls and floors. The higher the kappa-value, the greater the thermal mass, that is the more heat the element is able to store.
These values are integral to the use of energy calculation tools such as the Standard Assessment Procedure (SAP) and the Simplified Building Energy Model (SBEM), which support Part L of the Building Regulations, Conservation of Fuel and Power. As a result, it is important that they are calculated reliably.
U-value conventions in practice:
- Supports the Building Regulations Part L and other legislation on the energy performance of buildings.
- Helps raise an awareness of and understanding of U-values and kappa-values.
- Encourages a unified, consistent approach to calculating U-values and kappa-values.
- Explains calculation methods using worked examples for wall, roof and floor designs.
- Supports training programmes for practitioners carrying out energy assessments and using U-value calculation software.
- Provides guidance about calculating U-values using standard simplified methods.
Its contents include:
- Introduction.
- Summary outline of the U-value calculation method.
- The worked examples.
- References and further reading.
[edit] Related articles on Designing Buildings
- Approved document L.
- BRE articles on Designing Buildings Wiki.
- Building regulations.
- Building Research Establishment.
- Conventions for calculating linear thermal transmittance and temperature factors.
- Conventions for U-value calculations (2006 edition) BR 443.
- Energy performance certificate.
- Insulation.
- Kappa value.
- PA ratio.
- Simplified Building Energy Model.
- Standard Assessment Procedure.
- Thermal bridge.
- Thermal mass.
- U value.
- What do design professionals need to know about U-value calculation conventions?
Featured articles and news
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.
Comments