Roadblocks to 2013 improvements and achieving Zero Carbon (Part 2)

There have been numerous suggestions by some as to why they feel the consulted on 2013 regulations improvements should be watered down.

I can appreciate some of their reasoning behind certain arguments, whilst at the same time disagreeing with them on many of the issues raised. There have been arguments that until comprehensive data has been accumulated to test the as-built vs. designed assessment of new homes built under the 2010 regulations, the level of overall Carbon emissions for new dwellings in the 2013 amendments to Part L should not be changed from the values set in 2010 Part L.

Certainly there is an argument that improved understanding is necessary to determine just how much of a gap there really is between ‘designed’ and ‘as-built’ and to try and get an understanding of the reasons behind any gap. To ensure that houses are well designed and built better, whilst arguing that standards should not be improved upon would be a mistake. At every regulations change, the energy assessment model is improved upon, making the design calculations more likely to reflect the built dwelling and the suggestions in the consultations for 2013 to introduce a quality system for the whole process is surely a step in the right direction?

There have been issues raised from many quarters about the SAP energy assessment tool and its governance. Every time the regulations consultations come around, someone starts knocking SAP. It’s not 100% perfect, but each iteration has made it more complex and a better reflection of a dwelling’s emissions (assuming a standardised occupancy and heating regime at least). Behind each of the elements covered in SAP, there is generally speaking a substantial amount of technical papers and evidence to back up the formulae, efficiencies and adjustments provided in the underlying SAP tables. From experience, BRE & DECC have been quite willing to review particular issues when the regulations changes come around, provided a strong evidence base is provided to back up proposals. Their argument is that changes can’t be made without convincing evidence, otherwise adoption of particular measures might be made on false assumptions to the detriment of proven measures.

SAP Appendix Q provides a mechanism for claiming improved values for specific products, which I think largely works and the Product Characteristics Data File has come on a great deal in recent years. Although this in particular could be expanded upon in the future.

The Zero Carbon Hub’s review of modelling tools in 2010 noted that no modelling tool can perfectly represent the real world, but overall concluded that SAP actually compared well with other modelling tools available.

Several of the Hub’s suggestions for improvements have been included since, or are in line to be included for the next version.

The Passivhaus trust notes in their 2013 domestic regulations policy position document that: “The Passivhaus Planning Package software is at least as complete and robust an energy model as the SAP, and arguably contains an improved overheating treatment.” So from that I draw the conclusion that they feel SAP is at least reasonably robust and accurate, otherwise I’m sure that they would argue that PHPP was considerably better.

I agree it would be advantageous for a more open route to suggesting revisions.  I also hope that this time around, the new software will be available and approved for use well in advance of the regulation’s introduction. Hopefully the regulations will be committed to more quickly, to allow software manufacturers to get on the case earlier and get their software checked well ahead of the regulations commencement so that builders can start looking at new specifications in advance.

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Jon Ducker is a qualified energy assessor working for Kingspan Insulation Ltd. He has an extensive knowledge of energy efficiency, renewable energy systems and sustainability in buildings with an expert knowledge of the relevant sections of buildings regulations and standards and their interactions with SAP. He provides authoritative advice regarding energy assessments for a wide range of public and private sector clients.

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