News analysis Building Regulations
the future, asks Harris. ‘What is stopping the carbon factors from being significantly different again in another four years time? How can we be confident that what we are recommending now will provide significantly long term carbon savings? He says: ‘A one to two per cent
shift is possibly acceptable, but publication of a 23 per cent change is, surely, a major concern for the future.’ CIBSE’s technical director Hywel
Davies agrees that this change will pose significant challenges, making certain technologies less attractive to developers and designers. But a spokeswoman for the Department for Energy and Climate Change stresses that for most fuels – other than electricity – the carbon factors remain fairly constant: ‘Electricity is generated using a mix of different fuels, and this mix can have a significant impact on the factor that is derived for electricity. Market forces have a significant influence on the mix of fuels used to generate electricity. The factors also take account of the forecast for decarbonisation of electricity supply.’ Stuart Pocock, technical
director at the Renewable Energy Association, sees both the omission of consequential improvements (for existing buildings less than 1,000 sq m), and no requirement for a mandatory assessment for a building’s renewable energy potential, as ‘missed opportunities’. He also describes the reduction of emissions in the modelling software, SAP, for displaced electricity (down from 0.568 CF to 0.529 CF) as ‘disappointing’. ‘However, the increase in emissions of grid electricity from 0.422 to 0.517 will impact the take-up of heat pumps. We welcome the government’s intention to revisit this issue as a
Key changes in the four Approved Documents
New dwellings:
• The annual CO2 emission rate of the completed dwelling is now calculated using SAP 2009 and must not exceed the target set by reference to a notional dwelling with an additional overall improvement of 25 per cent relative to 2006 standards • Secondary heating is counted as part of the annual CO2 emission rate of the completed dwelling only when actually provided for, and credit is allowed wherever low- energy lighting is installed • Some of the reasonable limits for building fabric and services performance specifications are strengthened • Revised guidance is provided for avoiding thermal bridging at construction joints including
Existing dwellings:
• A general strengthening of energy efficiency standards that are considered reasonable for work on thermal elements, controlled fittings and controlled services in
part of RHI policy development,’ adds Pocock. Bernard Pratley, the Lighting
Industry Federation’s (LIF) technical manager, believes the ADs for Part L are a positive step for lighting in non-domestic buildings. ‘The government aim has been to further increase the energy efficiency of lighting in buildings, and as a result, the luminaire efficiency has been lifted from 45 to 55 luminaire lumens/Watt. However, we now have the controls factors available for both new and existing buildings where they were only available for existing buildings in the 2006 edition.
Shallovent2
existing dwellings • Amended guidance is given for historical and traditional buildings which may have an exemption from the energy efficiency requirements or where special considerations apply • Amended guidance is now given where an extension is a conservatory or porch that is not exempt from the energy efficiency requirements
Existing commercial/public buildings:
• A general strengthening of the energy efficiency standards that are considered reasonable for work on thermal elements, controlled fittings and controlled services in existing buildings • Amended guidance for historic and traditional buildings which may have an exemption from the energy efficiency requirements or where special considerations apply • Amended guidance is now given where an extension is a conservatory or porch that is
‘LIF believe that this is a good
step forward, in that the same design criteria are now used for both building types, and it also recognises the increased role that lighting controls now play in reducing the operating costs and energy usage of lighting in buildings.’ Ventilation manufacturer Vent-
Axia believes the new ADs for Part F (ventilation) and Part L will help to drive the adoption of low carbon ventilation as an industry standard. According to the company, the ADs set out, for the first time, a specific fan power requirement of less than 0.5 Watt/sec for intermittent fans used in both refurbishment and new
not exempt from the energy efficiency requirements
New commercial/public buildings:
• The notional building used to determine the TER (target emissions rate) is the same size and shape as the actual building, constructed to a concurrent specification and no improvement factor. Developers are still given the freedom to vary the specification, provided the same overall level of CO2 emissions is achieved or bettered • Amended guidance is provided on shell and core developments and first fit-out work • A revised procedure is provided for demonstrating that reasonable provision has been made to limit the effects of solar gain in summer • Revised guidance is provided for avoiding thermal bridging at construction joints, including the option of adopting a quality- assured accredited construction details scheme approach
Source: Government departments.
build developments. The industry clearly believes
that the new Part L 2010 will raise some challenges for specifiers and manufacturers, as well as bringing in much needed revisions and clarifications to the regulations. As the Journal went to press, the Department for Communities and Local Government said the national calculation methodology was still being ‘road tested’, but anticipated that it would be ready for release by the end of May. Once published, the methodology
should be available to view at
www.bre.co.uk See Legal column, page 24
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June 2010 CIBSE Journal
17
The All Year Round Performer
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