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Book Review – Guide to Part L of the Building Regulations. Conservation of fuel and power

by Mel Starrs on August 22, 2006

in Book Review, Part L

If, like me, you have been tearing your hair out, trying to get your head around Part L since long before April this year, this book may help alleviate some of those stresses. Available from RIBA and NBS, the Guide costs £25. The RIBA blurb is below:

Guide to Part L is a thoroughly researched, in-depth guidance for architects, construction professionals and building control officers about the complex new regulations governing the conservation of fuel and power in buildings. More than a general overview, this guide cuts through the jungle of new provisions and requirements to provide a logical, straightforward road map to compliance.

Guide to Part L comprises detailed step-by-step guidance to every section of the new four-part document, highlighting essential points and anomalies, and is illustrated by invaluable process flowcharts. It is backed up by extensive appendices that give further information about almost every issue affecting compliance, including: target emission rates, SAP, SBEM, U-values, overheating, air permeability, efficient boilers and controls, insulation, ventilation, efficient air conditioning, efficient light fittings, commissioning, log books and how to assess ‘simple payback’.

Written by the Building Performance Group at the BRE and published by NBS (the official publishers of the Approved Documents), this guide has been written specifically from the building professional’s perspective and will make the difficult Part L more easily assimilated and applied.

“Thankfully there is now a guide that unpicks these unfamiliar and rather tortuous new requirements … I can see it becoming a genuinely important reference work for architects, construction professionals and even building control officers as they grapple with the new approach”. Bill Gething, of Feilden Clegg Bradley LLP, chair of the RIBA Sustainable Futures Committee and the RIBA President’s Advisor on Sustainability.

Note the language used in the review: complex, jungle, anomalies, difficult. Putting it mildly, I think. In the Foreword to the book, Bill Gething describes the regulations as ‘unfamiliar and rather tortuous’.

The highlight of the book for me are the flow charts and the appendices, but there are plenty of other nuggets of information. Many of these I had surmised already, but it is gratifying to see the experts agree with me:

  • It is likely that U-values will have to exceed the standards of Part L 2002 in order to meet the TER
  • It will probably be necessary to design for an air permeability better than 10m³/h.m²@50Pa, particularly in buildings with mechanical ventilation and air conditioning
  • 2 calculations may be required for BER (Building Emission Rate) – a design stage which identifies the critical features of the design that will affect the energy performance of the building, and the second one when the building is completed. This version includes the actual results of air permeability, ductwork leakage and fan performance tests.
  • Solar gain needs to be controlled in areas which do not include comfort cooling (does this seem wrong to anyone else? Surely this encourages the use of comfort cooling, because by the time the solar overheating problem is identified, the building fabric and form are fairly fixed, and the only option for compliance is to add comfort cooling. The moral of the story being that architects will need to realise what an impact their design has on compliance at a very early stage)
  • Ductwork on systems served by fans with a design flow rate greater than 1m³/s should be tested for leakage

The one disappointment with the document is a lack of clarification on energy efficient building services and LZC technologies. Instead the book refers the reader to the ‘Non-Domestic Heating, Cooling and Ventilation Compliance Guide’ (pdf) and ‘Low or Zero Carbon Energy Sources: Strategic Guide‘ (pdf), neither of which are particularly light reading. I was hoping the Guide to Part L would fill the gaps between these two documents and the SBEM tools (including Hevacomp).

The intention of Part L 2006 was to conserve fuel and power in the built environment. The manifestation appears to be a complex, misunderstood calculation which whilst academically sound, does not lend itself well to how the industry operates today. The luxury of a period of time where the architect and engineer could fine tune the design using an iterative process before going out to tender is harping back to the ‘good old days’ when we used to have time to draw every pipe out in double line. Perhaps this change in regulations will see a return to longer design lead times? It will certainly require a greater deal of collaboration between the architect and the engineer at an earlier stage of design. It is not in the architect’s interest to design the fabric and form without consideration to Part L compliance and the building services, as this will undoubtably drive the capital cost of the building up, as technologies are added to the building in an effort to make it comply.