Part L2A 2010:- A case study

Mel Starrs recently published a worked Part L2A case study on her blog, Elemental. It’s a great article, and anyone with an interest in Part L2A should read it. Mel correctly identifies many of the issues with Building Regulations Part L2A compliance.

I wanted to highlight a few points Mel made and add my own thoughts:

• ‘Biomass is no longer the silver bullet it was under 2006’. In my opinion, this is a good thing. See here for more information. How can we be absolutely sure that the wood that feeds thousands of biomass boilers does not come from an unsustainable wood source?  Also, the transport costs in CO2 terms are much bigger when compared with those of transporting gas.
• ‘EPCs in 2010 are on a different scale to EPCs in 2006, so cannot be compared easily’. Agreed, 2006 and 2010 cannot be directly compared as they use different methodology, e.g. the TER (Target Emission Rate) is calculated differently.
• ‘A building which had an EPC of 40 under Part L 2006, gaining an Excellent under BREEAM 2008, does not automatically pass Part L 2010’. I cannot comment about BREEAM, but I agree with Mel's comment about the differences between 2006 and 2010. This is due to the fact that some of the conditions to comply with Building Regs are tougher now, because the CO2 emissions for a 2010 building will be on average 25% less than a building under 2006 Building Regs. In addition, this tighter regulation does not guarantee lower CO2.
• ‘A 25% improvement over 2006 does not automatically mean your building will pass under 2010 – the aggregate approach means there are no easy rules of thumb’. Mel is right about the average 25% improvement. In addition this is too complicated and can put more pressure in some building types e.g., shallow plan aircon. The theory behind this measure is to make the average 25% CO2 reduction cost-effective for all building types. We will see over the next few years if the theory behind the aggregate approach will work in practice. On the other hand, shallow plan aircon buildings have many low energy options like ‘night cooling strategy’ and ‘mixed mode operation’ which drastically reduce the amount of energy needs in air conditioning.
• ‘A low EPC under Part L 2010 does not guarantee Part L compliance’. I agree; this also is happening now with SBEM 2006.
• ‘The efficiency of building services has by far the greatest effect on ratings’. Absolutely - one of the issues with Building Regulations Part L compliance is that they focus too much on the efficiency of the source (e.g., boiler, heat pump, etc.) and very little on the emitter or controls. Please refer to the article from the MD of UHMA in Modern Building Services Journal, summer 2010. For example, at the moment in SBEM 2006, under floor heating obtains a worse EPC rating than a system using radiators. This is obviously totally wrong. The boiler with an under floor heating works at much lower temperature which makes the efficiency of a condensing boiler much higher, lowering the CO2 emissions.

I agree with Mel about the EPC rating being different between 2006 and 2010.

From October, SBEM 2010(v4) software will only be used for Building Regs compliance and EPC ‘as built’. Which means that EPC for existing building will still be assessed using SBEM 2006(v3.5) until 2011.

In my opinion, EPCs should be less variable and based only in the Building Emissions Rate. This will make the energy rating measurable and comparable between different dates, versions of SBEM and Building Regs.

Finally, we should not forget the operational ratings (DECs). Please refer to www.carbonbuzz.co.uk for some case studies. Building Compliance with Part L does not guarantee low CO2 emissions when the building is in operation. I hope that Operational Ratings coverage will grow with the EPBD recast which plans to include buildings over 250m2.

In general, I think we should focus more in efficient systems, better controls, and more low energy and low cost measures like shadings, automatic windows, night-cooling strategy, intelligent facades and naturally ventilated buildings.

With some reservations as Mel has pointed out, I hope that the new changes in Building Regs 2010 and the compliance software SBEM2010 will be the driving force for new, greener, more efficient and less CO2 intensive commercial buildings in UK for the years to come.

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