Thermal assessment (2nd edition) - PDF


For CWCT Member discounts on Documents and Events, please sign in to the Cladding Forum

The thermal assessment of window assemblies, curtain walling and non-traditional building envelopes (Second edition) 


This document is intended for use by the building design team, building envelope designers and building inspectors. It allows the early estimation of building envelope U-values, details the information required and describes methods for showing compliance of the final building envelope design with the requirements of Parts L-2A and L-2B of the Building Regulations 2010. It is expected that similar provision will be included in the Building Regulations for Scotland and Northern Ireland in due course.

Advice is given on which calculation methods are relevant to different types of construction. These include:

  • Stick curtain walling
  • Unitised and panellised walls
  • Rainscreen wall
  • Insulated panel walls
  • Window assemblies
  • The appendices show how detailed calculations should be undertaken to establish component U-values and the properties of their associated thermal bridges, and how these should be incorporated into a detailed calculation of the equivalent U-value of a zone of the building envelope.

    Finally, the document shows how the equivalent U-value of a zone of building envelope may be used as an input into software that models building energy use.

    David Metcalfe
    Stephen Ledbetter
    Status: Guidance Published: 2011
    ISBN: 978 1 874003 40 3 Pages: 68 Cost: CWCT members Free 
    Non-members £25