Conserving energy

NBS Technical Author Paul Swaddle looks at some of this year’s changes to Part L of the Building Regulations and their potential effect on work to existing buildings.

The current landscape

The Office of National Statistics provides data which indicates that 25 million homes have been built in England since 1850, and 4 million homes demolished or converted to other purposes.

According to the most recent Communities and Local Government 'English Housing Survey', 8.4 million homes in England date from pre-1945, of which 4.7 million are pre-1919. Fewer than 3 million new build homes have been constructed since 1990. Furthermore, around 3% of housing stock is unoccupied. 7.4 million homes are described as 'non-decent', including '4.8 million homes containing potentially serious hazards under the Housing Health and Safety Rating System.' There is clearly still a great deal of work involved in the upkeep and improvement of housing, and this represents only part of the total building stock across the country. Consider the renovation opportunities of non-dwellings, in particular, the extraordinary number of empty retail units in most town centres as a result of the economic downturn.

The statistics suggest that approximately 70% of today's existing building stock is likely to still be in use in 2050 – a date allocated in the 2009 UK Low Carbon Transition Plan as presenting an 80% cut in UK CO₂ emissions from levels of 1990 – a change of epic proportions. Whilst the targets are potentially subject to adjustment depending on the policies of this and future governments, similar commitment to energy efficiency will continue to be necessary, not just in the UK, but globally, as world population is predicted to rise to around 9 billion by 2050, and finite resources continue to be harvested at exponential rates. Energy efficiency is no longer just a buzzword, but a principle that will map the future of the construction industry.

Part L 2010

The recent changes to the Building Regulations (E&W) Approved Document L: Conservation of fuel and power (due to come into force on 1st October 2010), represent an awareness that meeting the targets requires action at every level of construction in the UK, especially work to existing building stock. Renovations and extensions to dwellings now require windows, boilers and water usage to result in further improvements in energy efficiency, with more emphasis on work to existing made across the documents. A change to the definition of renovation means that some minor work to existing buildings, that previously would have been exempt, must now comply with the Building Regulations, generally to improve the thermal efficiency of any building elements affected.

Approved Documents L1B and L2B contain new guidance on historic and traditional buildings. In particular, the statutory exemption for historic and traditional buildings has been amended. Clause 3.6 now indicates that listed buildings, buildings in a conservation area or on the Schedule of Ancient Monuments are exempt from the requirements 'only to the extent that compliance with the energy efficiency requirements would unacceptably alter the character or appearance...'

Clause 3.9 in Approved Document L1B reads:

'When undertaking work on or in connection with a building that falls within one of the classes listed above, the aim should be to improve energy efficiency as far as is reasonably practicable. The work should not prejudice the character of the host building or increase the risk of long-term deterioration of the building fabric or fittings.'

Where improvements can be made, such as providing upgraded insulation in roof spaces or improving the efficiency of lighting or appliances without damaging existing fabric, it is likely that such changes will now be required. The guidance suggests that 'special consideration' should be allowed where compliance would affect their character or appearance and that advice from local authority conservation officers should be taken into account by Building Control.

A recent presentation by Geoff Wilkinson, Building Regulations correspondent for the Architects' Journal, provided an interesting viewpoint on this, considering how it might affect the balance of power between planners and building control officers. Such energy efficiency improvements will require discussion, involving planners (regarding heritage and conservation concerns) and building control officers (presenting the case for viable improvements) at an early design stage; with the potential to increase costs of pre-application advice, and perhaps even jeopardize the feasibility of projects altogether.

Looking forward

Generally, opinion seems to indicate that whilst the 2010 changes to Part L have broadened its scope and may result in difficulty in bridging the 'performance gap' – between anticipated performance of building products and construction details in comparison to what is actually measured on site – the majority of projects will be able to comply by making a number of key changes.

However, the difficulty is in imagining how changes to the Building Regulations in 2013 – with a 44% reduction in emissions – and beyond to zero carbon in 2016, can realistically be matched using current building technologies and practice. The likelihood is that increasingly specific, complex and limited construction details will be required to comply. Also, as testing requirements are likely to become more demanding, ensuring that the performance gap is closed by the reality of on-site work is going to be essential. This may result in the duration of projects increasing, along with associated costs. In new build terms, more prefabrication and innovation in materials is urgently required to achieve the idealized equilibrium between airtightness, ventilation, heating and lighting.

Can further improvement be demanded from the traditional buildings that make up so much of UK building stock? Consider that with every passing year towards 2050, buildings once considered modern not only become significant examples of architectural styles in their own right but also develop a hunger for maintenance to increasing standards. How many buildings, especially conservation projects of historic importance, can improve energy efficiency in years to come, without resulting in irreversible damage, if not to the aesthetics, then to the layers of history behind the materials?

Related NBS information:

Articles:

• Lighting system efficiencies for Part L 2010
• Part L: Party walls – the heat is on

Written July 2010

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