The Future of Part L
As market leader in residential SAP calculations, Elmhurst Energy Systems has made significant input into the Government’s request for consultation on the revision of Part L.
Headlines:
- 25% reduction in carbon emissions
- Design stage calculations by accredited energy assessors
- Accredited Construction Detail (ACD) schemes
- Tightened control of conservatories
- “Black box” SAP software
Much is aimed at addressing the compliance gap between the ‘as designed’ and the ‘as-built’ stages.
25% Carbon Emission Reduction
The proposals suggest an alternative to a flat 25% carbon reduction, known as the ‘aggregate approach’ - different percentage reductions for different dwelling types. Elmhurst agrees with the Government’s preferred option of a flat rate reduction in the interests of simplicity.
As Designed Calculations
Elmhurst welcomes clarity as to who can provide as designed calculations. By using independent Accredited SAP Assessors, confidence can be given as to quality and consistency. If Building Control Officers have robust information, they can check compliance on site visits and ensure that that the finished property mirrors the designed specification.
Accredited Construction Details (ACDs)
Three options are proposed for calculating thermal bridging:
1. Replacement of published ACDs by new third party schemes, whereby developers utilise licensed ACD providers, who make site inspections to confirm compliance2. A 25% penalty on calculated values to reflect the lack of third party involvement
3. A global SAP default - likely to be conservative.
Elmhurst supports the review of ACDs, but suggests further options to add flexibility:
- Continued use of published ACDs, subject to on-site inspection by Building Control to confirm compliance
- Removal of the 25% penalty for calculated values when the calculations are verified by a competent third party
- Use of values from manufacturer’s technical literature, subject to third party testing and on site construction checking by building control.
Conservatories
Government has concerns that conservatories are often used as habitable parts of a dwelling with consequent high heat losses. The proposals seek industry views on whether to remove the current exemptions for small conservatories from Part L.
Elmhurst suggests retaining exemption for conservatories less than 30m2 with an approved installer scheme and notification to Building Control, similar to the arrangements for cavity wall insulation. To counter alteration to thermal separation after construction, an extension of the enforcement action time period from 12 months to perhaps 3-5 years is suggested.
In addition, Elmhurst has raised concerns about large and highly glazed extensions. Whole house “before” and “after” SAP calculations would carry the influence of Part L into the existing parts of the dwelling.
Black Box Software
Elmhurst has serious concerns about the proposals for central ‘black-box’ SAP software managed and maintained by Central Government. The current problems and lack of clarity with iSBEM, used for commercial buildings (Part L2), need not be replicated for SAP, which has a proven track record of effective software from independent suppliers.
Implementation
Elmhurst has stressed that legislation and approved documents need to be in place by April for an October 2010 implementation. This will give industry the chance to absorb the new requirements and achieve smooth transition.
Conclusions
Elmhurst supports the general thrust of the new Part L proposals. Significant carbon savings over Part L 2006 are required to meet the challenging targets to counter global warming.
Industry will be able to respond provided clarity is available as early as possible by Government. We hope that Government will have regard to our suggestions, but whatever the outcome, Elmhurst will be ready to provide our members and customers with products and guidance to meet their needs.
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