U-Value Conventions in Practice Worked Examples using BR 443

The aims of this BRE Trust report are to support the implementation of building regulations on conservation of fuel and power and legislation on the energy performance of buildings, to help raise awareness and understanding of U-values (thermal transmittances) and kappa-values (thermal mass values) and to encourage a unified, consistent and up-to-date approach to calculating these. The calculation methods are explained using worked examples for a number of wall, roof and floor designs. The examples can also be used to support training programmes for practitioners carrying out energy assessments and using U-value calculation software. Information is given about calculating U-values using standard simplified methods.

1. Aims and Introduction 2. Summary Outline of the U-value Calculation Method 3. Example 1: A Pitched Roof with Insulation at Ceiling Joist Level 4. Example 2: A Pitched Roof with Insulation at Rafter Level 5. Example 3: A Cavity Wall Fully-filled with Insulation 6. Example 4: A Cavity Wall with Internal Insulation (Non-contiguous Bridging) 7. Example 5: A Timber-frame Wall with Low-e Services Void (Contiguous Bridging) 8. Example 6: A Hybrid Light Steel Frame Wall 9. Example7: A Solid Ground Floor 10. Example 8: A Suspended Beam and Block Floor 11. References and Further Reading

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