The new Part L covering conservation of fuel and power will make radical changes from the design philosophy of the existing 2002 version. Most importantly the method of calculating insulation and thermal performance for each element individually will be replaced by a ‘whole building’ approach. The Approved Documents, detailing guidelines on how to meet the regulations, are eagerly awaited by the industry.
It had been expected that the documents would be laid before Parliament ahead of the summer recess with the aim of implementing the regulations by 4 January next year, the last date for putting the EU Energy and Performance of Buildings Directive into effect. It now appears this will be missed, with April 2006 seen as the most likely implementation date.
It will be practially impossible to meet the targets for improvement in energy performance through higher insulation alone. An improvement of 22% for domestic buildings and around 25% for non-domestic, compared with a 2002-compliant design, is called for.
Steel Construction Institute Senior Manager for Construction Technology Graham Raven said: “The pursuit of higher insulation as the major source of savings has reached the point of diminishing returns.” Though up to 10% of the improved performance can be achieved through the use of renewable energy, improving building airtightness will become significant, especially for industrial sheds.
For domestic houses, however, a steel-framed design will comply more readily than traditional brick and block, in which the need to add more insulation is leading to unacceptably thick walls.
A new Standard Assessment Procedure (SAP 2005) will be used for designing domestic buildings. BRE is developing software for the National Calculation Method, applying the whole building approach to designing non-domestic buildings, but following delays in awarding the contract, a test version of the software is not expected till October.