Continuing Professional Development Part L 2010
• The amendments made to Part L 2006 • What is required to meet the latest changes • How it might work in practice
revised in line with the 2010 changes, and the relevant software tools should automatically produce the specification list required to comply with the final part of 20D. The Approved Documents retain
the familiar four-volume set introduced in 2006, separating new and existing work in commercial and residential developments. The key changes are as follows:
Approved Document L1A — Dwellings For dwellings, the TER is still calculated using the Standard Assessment Procedure (SAP) in the same way as it was in Part L1A 2006. The SAP methodology is based on the BRE’s Domestic Energy Model (BREDEM), which provides a framework for calculating the energy consumption of dwellings. SAP works by assessing how much energy a dwelling will consume and how much carbon dioxide (CO2
) will be
Geoff Wilkinson, vice chair of the CIOB’s Building Standards Faculty, takes a look at the long-awaited changes to Part L 2010 and their practical effects
The next milestone on the road to zero carbon
THE 2010 AMENDMENTS to Part L are significant, and bring an estimated capital cost increase of around 4-8%, depending on the type of project. But the good news is that it should still be possible to gain compliance using traditional construction methods, and there is no specific requirement to incorporate renewable energy sources. The first major change is to Part L itself
(as opposed to the Approved Documents) in which a new requirement, 20D, has been introduced. As part of the application package (ie prior to works commencing), the designer must submit: • target CO2
emissions rate for the building (TER) • calculated CO2 emissions rate for the building as designed (DER);
• a list of specifications to which the building will be constructed. This is a significant issue for contractors
as any value engineering changes to the specification may result in the need to resubmit to Building Control, as minor product changes can result in significant variations in the TER. The only method for complying with
this requirement remains the National Calculation Method, which includes software tools such as the Standard Assessment Procedure for the Energy Rating of Dwellings (SAP), the Simplified Building Energy Model (SBEM) and Dynamic Simulation Modelling (DSM). The National Calculation Method was recently
emitted in delivering a defined level of comfort and service provision, based on standardised occupancy conditions. This enables a like-for-like comparison of dwelling performance and the required 25% improvement to be calculated. As a result, the elemental u-value
targets in Table 1 overleaf have not been raised by 25% across the board. instead, the majority of the 2010 changes take place within the black-box technology of the SAP software itself, so it is difficult to see clearly the effects of the changes. Nor will it always be possible to design down to the u-values given in Table 1 (see p36) and still achieve a pass. That said, early modelling by SAP assessor greenhouse Calculations indicates that the following specification for a typical house of 128m2
will still pass
without the need for renewables: • u-values: floor 0.13; walls 0.22; roof 0.13; windows 0.15; door 0.1
• Air-pressure testing: 3m3/hour/m2 @ 50Pa
• Mechanical ventilation with heat recovery: 1W per litre per second and 85% efficiency
• Enhanced construction details • 100% low-energy lighting One of the reasons why u-values
appear to have changed by less than 25% is that building fabric has pretty much reached the limit of economic return. A
> CONSTRuCTiON MANAgER | OCTOBER 2010 | 35
CPD
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