The Challenges and Opportunities of the 2006 Building Regulations Part L

John Field, Director, Target Energy Services Ltd. 17 Feb 2006

The Office of the Deputy Prime Minister is under pressure to meet its own deadline for the launch of the radically revised Approved Documents for Part L (Conservation of Fuel and Power) of the Building Regulations.

The pressure comes from the EU Energy Performance of Buildings Directive which is tied in with Part L and for which the UK is already in default because legislation has not yet been passed. Legislation for the Directive must also bring in energy certification and plant inspection programmes with huge impact.

All this adds up to a busy time for the mandarins and for the industry.

Current status

Part L of the Building Regulations is being used as a mechanism for implementing some key aspects of the EU Energy Performance of Buildings Directive, which has forced the government to bring forward its revision to April 2006 and to change the way in which the standards are set for new buildings in Approved Document ADL2A. The scope of application for existing buildings has also been widened and hardened in Approved Document ADL2B. Both Approved Documents (along with their domestic equivalents) were released in final draft form in September 2005 for an April 2006 launch date.

These extensive changes have required a lot of development work by the ODPM, its advisers and the industry generally, and great progress has been made. But the results are behind programme and seem worryingly complex which feeds another big unresolved issue of training and accreditation for designers, contractors, building control and certifiers.

The status of the EU Directive is somewhere between red and amber in this country. Since January 4th this year the UK government - along with most other EU Member States - is in default because it has not enacted legislation to implement the Directive. At least the UK now has an approved calculation method - a critical requirement - and a route for enacting some of the main requirements albeit a few months late. However, there is no announced timescale for enacting the rest of the Directive which covers such things as provision of energy performance certificates (which would be based on the calculation method in many cases) and energy efficiency inspections of plant.

The phasing-in of the various requirements of the Directive, such as energy certification of all large public buildings and of all existing buildings at time of sale or rent, should be known by now but has not been announced. The phasing-in must be completed by January 2009 but it can not all be put off until then.

Free downloads are available of the Approved Documents (look for building regulations at Office of the Deputy prime Minister); Simplified Building Energy Model; and the Energy Performance of Buildings Directive.

Summary of the 2006 Building Regulations Part L approach

The newbuild energy regulation is set in terms of the overall building energy use (expressed as CO2 emissions) of the actual building compared with a target which is a stated percentage improvement on a notional building just compliant with the 2002 regulations Part L (See more). Achieving this is the first of five criteria for newbuild in ADL2A - the others being limits on design flexibility, limiting solar gains in summer, quality of construction and commissioning, and providing information (See more).

For existing buildings in ADL2B there are five main applications: consequential improvements, extensions, material change of use, material alteration and work on a controlled service or fitting. These each have slightly different ways of applying the guidance provided subsequently in three categories: guidance on specific building services, thermal elements and providing information. (See more).

Key aspects of the EU Energy Performance of Buildings Directive are introduced by the Approved Documents. Directive Article 3 Adoption of a UK energy performance calculation method, Article 4 Setting energy performance standards, and Articles 5 & 6 Ensuring that new buildings and major refurbishment meet these standards, are all implemented in Criterion 1 of ADL2A (See more). The Directive’s Article 6 also affects the un-refurbished parts of renovated buildings and this is implemented through ADL2B Consequential improvements (See more).

Opportunities and challenges

From the myriad of changes and the opportunities they present one can cherry pick examples that emerge before the legislation has been finalised - or even formulated in some cases.

Air handling unit ventilation efficiency requirements, expressed as total system fan power per litre per second of ventilation, appear challenging at for example 2.0 W per l/s for a standard configuration new air handling unit, and 2.5 W per l/s in existing buildings. These will be very difficult to achieve and will require larger dimensioned ductwork and air handling units. It may not be cost effective to provide full flow primary air such as conventional VAV under these conditions.

Ductwork design and testing to HVCA DW/144 - this new requirement will test specifiers, contractors and commissioning engineers.

General office, industrial and storage area lighting systems are to be designed to a fall-back limit of 45 luminaire-lumens per circuit Watt. But the Notional Building system allowance at 3.75 circuit Watts per 100 lux is reduced by 28% for the Target Emission Rate calculation allowing only 10.4 watts/m2 for 400 lux lighting, including gear and any effect lighting. Of course this is only part of the overall Building Emission Rate calculation and so any excess power demand for lighting could be made up elsewhere - but where?

Low or zero carbon energy technologies - the 10% reduction in the Target Emission Rate from use of renewables or other low carbon technologies will prove testing, even though it can be vired over from other efficiency improvements. To help with this the ODPM refer to their Low or Zero Carbon Sources Strategic Guide, but designers may also refer to the Greater London Authority’s Renewables Toolkit (available from, and an on-line implementation of this approach at

Design teams and clients will have to get used to the new regime of provision of information which is generally covered by requirements for log books. The Approved Documents refer to the CIBSE Log Book Toolkit TM31, which provides a format for describing a building and its systems, their features and how they should be operated, using 20 or 30 pages in contrast to the 20 to 30 kilograms of conventional and impenetrable O & M manuals.

Design practices need to develop and understand the sensitivity of the Building Carbon Emission Rate to parameters that designers can vary, like U-values and the efficiencies of major plant such as fans, boilers and cooling plant. Hoare Lea have presented conclusions from pioneering analyses of this sort - results exhibit the usual lack of sensitivity to U-values - but the recent changes to the official software may encourage a re-visit.

The industry generally has a desperate need for programmes of training and accreditation for design, building control, certification and inspection. CIBSE are starting a substantial Carbon Trust funded project which will directly feed into this process and also work towards life beyond the regulations for a “Platinum” standard. In addition the project is to measure achievements and push things forward with a one hundred day Carbon clean-up campaign.

The future

Let’s get the present out of the way first. The final form of the Approved Documents and the SBEM calculation procedure are awaited with interest. Even more urgently we need a credible training and accreditation programme which will start to produce the required large numbers of designers, building control assessors, plant inspectors and certifiers. It would be interesting to know the plan and timescales for the certification and inspection required for the EU Directive, especially for Operational Ratings which shows how a building is actually performing in use.

In the meantime we can work out how to economically achieve ten Watts per m2 total for general lighting and two Watts per litre per second for air handling plant.