This website provides:

•  Guidance of understanding the Building Regulations Approved Document, Part L 2006 version

The 2006 version of Part L of the Building Regulations changes the method of compliance completely.  There is no longer elemental compliance, which means no building envelope package can comply with Part L alone.  Only a whole building can comply with Part L in terms of a whole building carbon dioxide emission by taking account of the building envelope performance, solar gain, and all the building services.  Individual building envelope zone/package shall meet the specification to ensure the compliance with Part L in terms of the whole building carbon emission rate.

•  Introduction to CAB/CWCT thermal guidance

The CAB/CWCT thermal guide gives guidance on how to calculate the overall U-values of different types of cladding, and the overall U-value of a building envelope zone/package.  A series of blue curves have been developed to allow a quick estimation of the overall U-value at the early design stage.  The guide also gives detailed methods of calculating the component U-values of complex assemblies.  Furthermore it gives guidance on how to input curtain walling data into the national calculation methodology software SBEM.

•  A review of British and European Standards 

There are a series of Standards relating to heat transfer assessment through a building envelope.  The European Standard BS EN ISO 6946 specifies the method of calculating the U-value of a layered construction.  For constructions with more complex geometry, BS EN ISO 10211 Parts 1 and 2 specify the method of assessing the heat transfer though point and linear thermal bridges respectively.  For building elements with smaller dimensions such as windows and doors, the European Standard BS EN ISO 10077 provides a method for assessing heat transfer through windows as a whole from the thermal transmittances of their components.  Part 1 gives the area-weighted method for calculating the overall thermal transmittance of the window.  It also gives simple methods of calculating the thermal transmittances of the frames using charts and tables for different types of window frames and glazing units.  Part 2 gives a more accurate method of calculating the thermal transmittance of the frames by numerical simulation using computer software based on finite element analyses or the finite difference method. 

A scheme showing how to use these Standards and the relationship with otherSstandards is given in this web site.
 
A list of the international Standards relating to this subject, which are in use (EN, ISO, IEA) or in preparation (CEN), is given.  Different national Standards (UK, Germany, USA and Canada) currently in use are listed.  An overview of the international Standards in use or in preparation that are related to window heat transfer has been established.

•  A review of the software for the assessing heat transfer through façade.
Software used for thermal analysis can be classified into several categories.  The level of sophistication and hence number of properties that can be calculated varies.  A checklist showing the possibilities and the capacities of several types of commonly used software are given.  Lists of software for the calculation of the thermal transmittance and for the fenestration energy rating have also been given.

•  A brief guide of domestic window energy rating schemes

The British Fenestration Rating Council (BFRC) has been set up to establish a national rating system for the thermal performance of fenestration products.  The Domestic Window Energy Rating (DWER) scheme has been introduced to 2006 Part L A1.  Similar schemes have been developed in the United States and Canada by their window industry.  A list of these procedures and publications has been added to this web site.  

•  A brief introduction of heat transfer due to temperature difference

Three heat transfer mechanisms - conduction, convection, and long-wave radiation - are explained briefly in this section.  More importantly, the factors that affect the heat transfer due to each individual mechanism and the combined effect of mechanisms.

•   Research projects

Over the years, CWCT has been carrying out various research projects.  This section gives details of recently finished and on going research projects.