Understanding the requirements of the new Building Regulations
Myriad changes and opportunities — John Field
The 2006 Building Regulations present new challenges and opportunities for building-services engineers. JOHN FIELD is chairman of the Carbon Task Group of the Chartered Institution of Building Services Engineers and outlines their scope.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. The UK must introduce national legislation to implement the Directive. This process is made even more complicated by different implementation protocols for England & Wales, Scotland and Northern Ireland. The directive brings 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. However, 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 4 January the UK Government and most other EU member states are in default because they have 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 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 cannot all be put off until then. All the publications mentioned (Approved Documents, national calculation software, and EU Directive text) are available as official free downloads.* Summary of the 2006 Building Regulations Part L approach The new-build energy regulation is set in terms of the overall building energy use (expressed as carbon-dioxide 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 ( Table 1). Achieving this is the first of five criteria for new buildings in ADL2A; the others are limits on design flexibility, limiting solar gains in summer, quality of construction and commissioning, and providing information (Table 2).
Table 1: Procedure for establishing an acceptable Building carbon-dioxide Emission Rate (BER)
• Calculate building energy use and convert to CO2 emissions using stated carbon factors to give BER.† • Calculate energy use and carbon emissions of the notional building — an equivalent building just compliant with the 2002 Building Regulations, Part L.† • Reduce the energy use of the notional building by 20% (or only 15% if naturally ventilated) and then by a further 10% (nominally for renewables) to produce the Target Emission Rate (TER). • The BER must not be higher than the TER. † The energy use of the actual and notional buildings must be calculated using the EU Directive-compatible National Calculation Method, which means either the Simplified Building Energy Model (SBEM) or other approved software. In either case the official definitions of activity areas and standard usage profiles must be employed, which are fully integrated into the official SBEM software
Table 2: Summary of new-build criteria under ADL2A. Five criteria must be satisfied, as summarised with a checklist in Appendix A of ADL2A, and paraphrased below.
1: Achieving an acceptable Building CO2 Emission Rate (BER). The BER calculated using the National Calculation Method must be no greater than the Target Emission Rate (TER), which is the emission rate for a notional building compliant with 2002 Part L and reduced by a stated percentage (28% for air-conditioned offices). See ADL2A paragraphs 19 to 26. 2: Limits on design flexibility. These resemble elemental standards and are included to provide a quality back-stop in key areas, including U-values, air permeability, energy meters, air-handling plant efficiency, duct leakage, insulation, lighting system efficiency. See ADL2A paragraphs 27 to 58. 3: Limiting solar gains in summer. Where there is no cooling, total gains including solar and internal gains are limited (to 35 W/m2), and it must be shown that there will be no more than a reasonable number of hours per year above 28°C. See ADL2A paragraphs 59-62. 4. Quality of construction and commissioning. The BER must be recalculated as constructed with any design changes and using measured permeability. The commissioning process must be signed off, for example with reference to CIBSE Commissioning Code M and leakage testing of ductwork. See ADL2A paragraphs 63-80). 5. Providing information. Information must be provided on fixed building services, their features and intended operation. One way to show compliance is by following the CIBSE Building Logbook Toolkit TM31. See ADL2A paragraphs 81-83.
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 service; thermal elements and providing information (Table 3). 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 and 6 ‘Ensuring that new buildings and major refurbishment meet these standards’, are all implemented in Criterion 1 of ADL2A (Tables 1 and 2). The directive’s Article 6 also affects the un-refurbished parts of renovated buildings, and this is implemented through ADL2B ’Consequential improvements’ (Table 3)
Table 3: Summary of requirements for existing buildings under ADL2B
Consequential improvements apply where the floor area is over 1000 m2 and there is increase in capacity of a fixed building service, or a new extension. The principal works (to new or extended parts) must comply with guidance below, and consequential improvements (to the rest of the building) must bring the thermal properties up to stated values, and then upgrade services over 15 years old, install metering and low-zero carbon within stated economic limits and a cap of 10% of principal works cost. The cap does not apply to the thermal property improvements. See ADL2B paragraphs 12-16. Extensions. Large extensions over 100 m2 and 25% of floor area fall within ADL2A and so must achieve a satisfactory BER. Conservatories have special stated requirements. Other extension works broadly follow the thermal element guidance and services and fittings guidance below. See ADL2B paragraphs 17-26. Material change of use applies when, for example, the building becomes a public building or ceases to be a dwelling. Works broadly follow the thermal element guidance and services and fittings guidance below. See ADL2B paragraphs 28-31. Material alteration applies when a service or fitting ceases to comply with the regulation or whose compliance level becomes worse. Works broadly follow the thermal element guidance and services and fittings guidance below. See ADL2B paragraphs 32-33. Work on a controlled service or fitting, i.e. one to which any of the Regulations Parts G,H,J L or P apply. Windows, rooflights and doors to comply with stated U-values (1.8 W/m2K for a whole new window or rooflight, 2.2 W/m2K for a replacement). Controlled services to meet standards below. Commissioning to be notified complete in line with CIBSE Code M and duct-leakage testing. See ADL2B paragraphs 34-44. Guidance on specific building services. Heating and cooling to follow the heating or cooling Compliance Guide. Air-handling-plant specific fan power to comply with limits (e.g. 2.5 W/l/s for standard HVAC plant) and part-load efficiency. Lighting to 45 luminaire-lumens per circuit Watt in general office, industrial and storage areas; other general areas to 50 lamp-lumens per circuit Watt. Effective occupant lighting controls will comply. See ADL2B paragraphs 45-68. Thermal elements which are new, replaced, renovated or retained. New element U values to meet tabled values (e.g. wall 0.30, flat roof 0.20 W/m2K), and replacement elements (wall 0.35, flat roof 0.25 W/m2K). Renovated elements are to these same values where more than 25% is renovated and within 15-year payback. Retained elements to follow tabled values of threshold and improved U-values (e.g. flat roof 0.35 to 0.25 W/m2K). See ADL2B paragraphs 69-76. Providing information. Update the existing log book, or provide a new one, as guidance in the CIBSE Building Logbook Toolkit TM31 (see ADL2A paragraphs 81-83). See ADL2B paragraphs 77-80
Opportunities and challenges
From the myriad changes and the opportunities presented, 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/l/s for a standard-configuration new air-handling unit and 2.5 W/l/s in existing buildings. These will be very difficult to achieve and will require larger 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 is a new requirement that 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 lx is reduced by 28% for the Target Emission Rate calculation, allowing only 10.4 W/m2 for 400 lx lighting, including gear and any effect lighting. This is only part of the overall Building Emission Rate calculation, so any excess power demand for lighting could be made up elsewhere — but where? The recommended 10% reduction in the Target Emission Rate from use of renewables or other low-carbon technologies will prove testing, even though it can be carried over from other efficiency improvements. To help, the ODPM refers to its ‘Low or zero carbon sources strategic guide’, but designers may also refer to the Greater London Authority’s ‘Renewables toolkit’ (available from www.london.gov.uk), and an on-line implementation of this approach at www.epcert.co.uk. Design teams and clients will have to get used to the new regime of providing the information that 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; it uses 20 to 30 pages, in contrast to the 20 to 30 kg 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 has 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 is starting a substantial project funded by The Carbon Trust 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 100-day carbon clean-up campaign. The final form of the approved documents and the SBEM calculation procedure are awaited with interest. Even more urgently, we need a credible training programme that 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 show how a building is actually performing in use. In the meantime we can work out how to economically achieve 10 W/m2 total for general lighting and 2 W/l/s per second for air-handling plant. John Field is chairman of the CIBSE Carbon Taskforce and director of Target Energy Services. * Official free downloads of key documents
Building Regulations Approved Documents. Current (late 2005) drafts of the 2006 Approved Documents ADL2A and ADL2B from www.odpm.gov.uk under Building Regulations. EU Energy Performance of Buildings Directive text from www.diag.org.uk/pdf/EPD_Final.pdf National calculation method Simplified Building Energy Model (SBEM) from www.ncm.bre.co.uk