U-value Calculation Competent Person Scheme launched by BBA and TIMSA

U-value and Condensation Risk Analysis calculations can now be obtained from quality assured Competent Persons who are members of a new voluntary scheme which was launched on the 1st April 2010.

The scheme is operated by the British Board of Agrément (BBA) and is designed to promote the production of accurate, objective and consistent U-values and condensation risk calculations for the building industry.

Competent Persons calculations covered by this scheme can be identified by the use of a BBA Competent Persons Logo. For example, calculations produced by Steve Channon of BuildDesk Ltd would be identified by the following unique Logo.

BBA_TIMSA_logo - BuildDesk

 This logo uniquely identifies the individual and company who produced the calculation. Details of their competency can then be checked against information on the BBA website.

More details on the scheme are available here on the BBA website.

Why introduce a scheme?

Well for some very good reasons……

A research report produced for Energy Efficiency Partnership for Housing (EEPH) and Communities and Local Government (CLG) in 2009 entitled ‘Research into Compliance with Part L of the Building Regulations for New Homes’ produced some embarrassing results. It was found that 10% of the submitted reports showed a failure to comply with Criteria 1, the Target Carbon Dioxide Emission rate or TER. Even worse than this, when audited for errors and re-calculated more than 20% of submitted calculations failed to comply with Criteria 1. So based on this sample we can extrapolate that 20% of the submissions could be expected to produce substantially more CO2 than was the aim of the entire regulatory process! Not very comforting news for either the industry or Government.

Of particular interest was the observation was that SAP assessors are being given incorrect, incomplete or contradictory design information. This may not be a great surprise for those close to the industry but the most common offender was U-value information. Many U-value entries can be more aspirational rather than true reflections of calculated performance, let alone the delivered performance on site. Can the calculation withstand scrutiny, is it accurate and has it been produced by a ‘competent person’ from reliable information on credible calculation software? Indeed have the correct products been supplied and installed correctly and calculations modified where required?

Not surprisingly there is increasing talk in Regulatory circles of the need to extend Competent person schemes to include U-value calculations. The BBA and TIMSA have now developed and launched such a scheme which may become recognised in future Building regulations. It certainly seems worthwhile when set against the growing complexity of solutions and the increase in modern methods of construction. Without improvements to the existing process we are unlikely to ever achieve the ambitious CO2 reduction targets when calculations can be flawed from the start. It’s time to raise our knowledge.

How can BuildDesk help you?

Software tools

Our BuildDesk U 3.4 software is designed to produce clear, accurate, U-value and Condensation Risk Analysis (CRA) calculations and help you to comply with the BR 443 Conventions for U-value calculations document and the supporting standards.


BuildDesk deliver comprehensive U-value and Condensation Risk Analysis training for individuals and organisations at our premises in Bristol. BuildDesk is also able to provide in-house training for larger organisations. Our training is delivered by Steve Channon who is one of the first Competent Persons recognised in this scheme.