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Title
Conventions for calculating linear thermal transmittance and temperature factors
Author
Tim Ward and Chris Sanders
Date
Sep 20, 2007
Price
£37.50
Stock code
287259
ISBN
978-1-86081-986-5
Abstract
This guide gives the conventions that should be followed by numerical modellers to produce consistent, reproducible results. For building regulation purposes, two key modelling outputs, temperature factor and linear thermal transmittance, are identified. These key outputs will enable designers to confirm the adequacy of particular junction details and help with the development of novel solutions to improve the thermal performance of junctions. 48 pages.

Contents:

1. Introduction
2. Numerical modelling
Two- or three-dimensional modelling
Specification of the numerical model
Thermal conductivities of materials
Treatment of air spaces
Surface heat transfer (surface resistances)
Refining the mesh size
Reporting of temperatures and heat flows
3. Thermal bridging at junctions
Psi-value
Temperature factor, fRsi
4. Junction types
Roof junctions
Junctions around openings
Ground floors
Other junctions
5. Point thermal bridges, chi-values
6. Reporting of calculations
7. References
Appendix A. Detailed Input and Output from a numerical model
Appendix B. Validation examples for calculating psi and f

Future updates to this guidance will be found at http://www.bre.co.uk/br497updates
Subject/Keywords
BR497, modelling, thermal bridging, thermal bridges, junctions, eaves, detailing, heat transfer.
Publisher
BREPress BREPress
PDF version available
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