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Energy efficiency in British housing

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Domestic housing in the United Kingdom presents one of the major opportunities for achieving the 20% overall cut in UK carbon dioxide emissions targeted by the Government for 2010.

Carbon emissions

Although carbon emissions from housing have remained fairly stable since 1990 (due to the increase in household energy use having been compensated for by the 'dash for gas'), housing accounted for around 30% of all the UK's carbon dioxide emissions in 2004 - 40 million tonnes[1] - up from 26.42% in 1990 as a proportion of the UK's total emissions.[2] The Select Committee on Environmental Audit noted that emissions from housing could constitute over 55% of the UK's target for carbon emissions in 2050.[3]

A 2006 report commissioned by British Gas[4] estimated the average carbon emissions for housing in each of the local authorities in Great Britain, the first time that this had been done. This indicated that housing in Uttlesford (Essex) produced the highest emissions (8,092 kg of carbon dioxide per dwelling). This was 250% higher than than housing in Camden (London) which produced the least (averaging 3,255 kg). Among the 23 towns included, Reading had the highest emissions (6,189 kg), with Hull the lowest (4,395 kg). The variations are due to a number of factors, including the age, size and type of the housing stock, together with the efficiency of heating systems, the mix of fuels used, the ownership of appliances, occupancy levels and the habits of the occupants.

Zero carbon ambition

In the December 2006 Pre-Budget Report[5] the Government announced their 'ambition' that all new homes will be 'zero-carbon' by 2016 (i.e. built to zero-carbon building standards). To encourage this, an exemption from Stamp duty land tax is to be granted, lasting until 2012, for all new zero-carbon homes up to £500,000 in value.[6]

Whilst some organisations applauded the initial announcement of the scheme, in the pre-budget statement from the then UK Chancellor, Gordon Brown, others are concerned about the government's ability to deliver on the promise.[7][8]

Domestic energy use

 
A tower block in Cwmbrân, South Wales

The housing stock in the United Kingdom is amongst the least energy efficient in Europe.[9] In 2004 housing (including space heating, hot water, lighting, cooking, and appliances) accounted for 30.23% of all energy use in the UK (up from 27.70% in 1990)[10]. The figure for London is higher at approximately 37%.[11]

In view of the progressive tightening of the Building Regulations' requirements for energy efficiency since the 1970s (see the history section below), it might be expected that a significant cut in domestic energy use would have occurred, however this has not yet been the case.

Although insulation standards have been increasing, so has the standard of home heating. In 1970, only 31% of homes had central heating. By 2003 it had been installed in 92% of British homes,[12] leading in turn to a rise in the average temperature within them (from 12.1°C to 18.20°C).[13] Even in homes with central heating, average temperatures rose 4.55°C during this period.

At the same time, the increase in the number of households, increasing numbers of domestic electrical appliances, an increase in the number of light fittings, reduction in the average number of occupants per household, plus other factors, had lead to an increase in total national domestic energy consumption from around 25% in 1970 to about 30% in 2001, and remained on an upward trend (BRE figures).

The figures for energy consumed by end use for 2003.[14]

  • Space heating - 60.51% (57.61% in 1990)
  • Water heating - 25.23% (25.23% in 1990)
  • Appliances and lighting - 13.15% (13.4% in 1990)
  • Cooking - 2.74% (3.76%)

Building Regulations

The 1965 Building Regulations introduced the first limits on the amount of energy that could be lost through certain elements of the fabric of new houses. This was expressed as a u-value - the amount of heat lost per square metre, for each degree Celsius of temperature difference between inside and outside.

In effect the Target Insulation is a ration of 1.33 W/m^2/K of floor area (Document L 2006). So to keep your square metre warm you are limited as to how much energy you can use. This is slightly regressive in that richer people live in bigger houses which tend to have a lower surface area /floor area, although this is partially offset by them being detached.

These limits were tightened following the 1973 oil crisis, and on several subsequent occasions (see below. Despite this, UK insulation levels have remained low compared to the EU average.[15]

2006 changes

The energy policy of the United Kingdom through the 2003 Energy White Paper[16] articulated directions for more energy efficient building construction. Hence, the year 2006 saw a significant tightening of energy efficiency requirements within the Building Regulations (for earlier regulations, see separate section below).

With the long term aim of cutting overall emissions by 60% by 2050, and by 80% by 2100, the intention of the 2006 changes was to cut energy use in new housing by 20% compared to a similar building constructed to the 2002 standards. The changes were the first to the regulations brought about by the desire to reduce emissions, though some have raised doubts about whether they will actually achieve the 20% cut (see criticisms section).

In the 2006 regulations, the u-value was replaced as the primary measure of energy efficiency by the Dwelling Carbon Dioxide Emission Rate (DER),[17] an estimate of carbon dioxide emissions per m² of floor area. This is calculated using the Government's Standard Assessment Procedure for Energy Rating of Dwellings (SAP 2005).[18]

In addition to the levels of insulation provide by the structure of the building, the DER also takes into account the airtightness of the building, the efficiency of space and water heating, the efficiency of lighting, and any savings from solar power or other energy generation technologies employed, and other factors. For the first time, it also became compulsory to upgrade the energy efficiency in existing houses when extensions or certain other works are carried out.

Criticism of the 2006 changes

Some organisations have raised doubts over the claim that the changes will result in a 20% saving. Issues cited have included alleged problems with the calculation methods, the limitations of the modelling software, and the specification of the reference building used in the model.[19] For example, a 2005 study sponsored by the Pilkington Energy Efficiency Trust[20] indicated that the savings would only be in the region of 9%.[21]

There are also concerns about enforcement, with a Building Research Establishment study in 2004 indicating that 60% of new homes do not conform to existing regulations.[22] A 2006 survey for the Energy Saving Trust revealed that Building Control Officers considered energy efficiency 'a low priority' and that few would take any action over failure to comply with the Building Regulations because the matter 'seemed trivial'.[23]

Despite the tightening of the requirements and previous loopholes, the regulations have been criticised by some for not going further. Criticisms include the exclusion of domestic appliances from the calculations, not requiring provision to be made for retrofitting of solar or other technologies, lack of remedial requirements if airtightness tests are failed, and for not requiring greater insulation standards.

A more fundamental criticism by some is that even if the expected 20% cut is achieved, this falls far short of achieving the long term goal of a 60% cut in carbon dioxide emissions by 2050. The London Sustainable Development Commission,[24] for example, has calculated that to meet the 60% target, all new developments would have to be constructed to be carbon-neutral with immediate effect (using zero energy building techniques), in addition to cutting energy used in existing housing by 40%.

Future changes

The Government have signalled the next review of energy performance standards in 2010.[25]

Following the announcement that all housing should be build to emit zero carbon emissions by 2016, in the consultation document Building a Greener Future: Towards Zero Carbon Development it is proposed that the 2010 revision should require a further 25% improvement in the energy/carbon performance, in line with earlier government proposals from 2004. It is further envisaged that there would be a 44% improvement in 2013, compared to 2006 levels. This would then be followed by the adoption of a zero carbon requirement in 2016, applied to all home energy use including appliances.[26]

These steps in performance would align the energy efficiency requirement of the Building Regulations with those of Levels 3, 4 and 6 of the Code for Sustainable Homes in 2010, 2013 and 2016 respectively.

 
Home energy performance rating charts

Home Energy labelling

Originally, from June 2007, all homes (and other buildings) in the UK would have to undergo Energy Performance Certification before they are sold or let,[27] in order to meet the requirements of the European Energy Performance of Buildings Directive (Directive 2002/91/EC).[28] (This has now been put back to August 2007, and will operate on a phased introduction basis, starting with large 4 bedroom homes). This will provide the owner or landlord with an 'energy label' so that they can demonstrate the energy efficiency of the property, and is also to be included in the new Home Information Packs.

It is hoped that energy labelling will raise awareness of energy efficiency, and encourage upgrading to make properties more marketable. Incentives may be available for carrying out energy conservation measures.[29]

For new building, SAP 2005 calculations are to form the basis for the certification, while the National Home Energy Rating scheme (NHER) will be used to assess existing properties. It is estimated that only 10% of the nation's housing will score above 60 on the scale, although most will score above 40.[30]

Other rating schemes

Another rating scheme of note is the Government sponsored EcoHomes rating, mostly used in public sector housing, and only applicable to new properties or major refurbishments. This actually measures a range of sustainability issues, of which energy efficiency is only one. EcoHomes is to be replaced by the Government's Code for Sustainable Homes in 2007.

The Energy Saving Trust set requirements for 'good practice' and 'advanced practice' for achieving lower energy buildings,[31] while the Association for Environment Conscious Building's CarbonLite programme specifies Silver and Gold standards, the latter approaching a zero energy building.

Grants

 
rooftop turbine

The Government's low carbon buildings programme was launched in 2006 to replace the earlier Clear Skies and Solar PV programmes. It offers grants towards the costs of solar thermal heating, small wind turbine, micro hydro, ground source heat pump, and biomass installations. As of January 2007 funding for grants is proving insufficient to meet demand.[32]

A similar scheme, the Scottish Community and Household Renewables Initiative operates in Scotland, which also offers grants towards the cost of air source heat pumps.

Local government

Under the Home Energy Conservation Act 1995, local authorities are required to consider measures to improve the energy efficiency of all residential accommodation in their areas. However they are not required to implement any measures, and only a minority of local authorities have done anything to inform or help households other than those in social housing and the fuel poor. It was expected that the Act would result in a 30% cut in energy usage between 1996 and 2010. An overall cumulative improvement of 14.7% was reported to DEFRA for the year ending March 2004, but a large part of this would have happened without HECA.[33]

In the South most local authority housing was sold off in the 1980s-90s under RTB (Right to buy scheme), so the remaining stock is small. The authority has no/limited responsibility for the sold houses.

Demonstration and pioneering projects

File:Bedzed.jpg
BedZED zero energy housing

One of the most important energy efficiency demonstration projects was the 1986 Energy World exhibition in Milton Keynes, which attracted international interest. 51 houses were built, designed to be at least 30% more efficient than the Building Regulations then in force. This was calculated using the Milton Keynes Energy Cost Index (MKECI), a test-bed for the subsequent SAP rating system and the National Home Energy Rating scheme.

The Beddington Zero Energy Development (BedZED), a non-traditional housing scheme of 82 dwellings near Beddington, included zero energy usage as one of its key features. The project was completed in 2002 and is the UK's largest eco-development. The only energy used is generated from renewables on site. Due to their superinsulation, the properties use 73% less energy for space heating compared to those built to the 2002 Building Regulations, while the reduction for water heating is 44%.[citation needed]

The Green Building in Manchester City Centre and has been built to high energy efficiency standards and won a 2006 Civic Trust Award for its sustainable design.[34] The cylindrical shape of the ten storey tower provides the smallest surface area related to the volume, ensuring less energy is lost through thermal dissipation. Other technologies including solar water heating, a wind turbine and triple glazing.

The South Yorkshire Energy Centre at Heeley City Farm in Sheffield is an example of refurbishing an existing property to show the options available.[35]

The EcoHouse in Leicester[36] incorporates products and materials selected for their green credentials, and operates as an advice centre with videos on products and suppliers, and refurbished computers for sale.

International comparisons

International comparisons of particular note include:

  • The 1977 Danish BR77 standard (the first to set demanding energy efficiency requirements).
  • The SBN-80 (Svensk Bygg Norm) 1980 Swedish Building Standards, which in 1983 was in advance of the UK 2002 standards.[37]
  • The voluntary Canadian R-2000 standard, to which around 14,000 houses had been built in the 10 years to 1992.[38] Since then many more have been built in Canada, in Japan, and in various other countries including a number in the UK. Currently energy savings of 30% to 40% are typically achieved in Canada.[39]
  • The voluntary German Passivhaus standard. Properties built to the standards use approximately 85% less energy and produce 95% less carbon dioxide compared to properties built to the UK's 2002 standards. Over 6,000 such houses have been built across several European countries.[40]

Forschung

In 2005 the Select Committee on Environmental Audit expressed their concern that there was a lack of significant funding for research and development of sustainable construction methods,[41] with funding for the Building Research Establishment having been 'drastically' cut in the previous 4 years. As a result, many of the sustainable building materials used in the UK are imported from Germany, Switzerland and Austria - some of the the countries that have been prominent in research.

Existing housing stock

Even if all new housing does become 'zero carbon' by 2016, the energy efficiency of the remainder of the housing stock would need to be addressed.

The 2006 Review of the Sustainability of Existing Buildings revealed that 6.1 million homes lacked an adequate thickness of loft insulation, 8.5 million homes had uninsulated cavity walls, and that there is a potential to insulate 7.5 million homes that have solid external walls. These three measures alone have the potential to save 8.5 million tonnes of carbon emissions each year. Despite this, 95% of home owners think that that the heating of their own home is currently effective.[42]

Historic Building Regulations energy efficiency requirements

The u-value limits introduced in 1965 were:[43]

  • 1.7 for walls
  • 1.4 for roofs

Following the 1973 oil crisis, these were tightened in 1976 to:[44]

  • 1.0 for exposed walls, floors and non-solid ground and exposed floors
  • 1.7 for semi-exposed walls
  • 1.8 average for walls and windows combined
  • 0.6 for roofs

1985 saw the second tightening of these limits, to:

  • 0.6 for exposed walls, floors and ground floors
  • ?.? for semi-exposed walls
  • 0.35 for roofs

These limits were reduced again in 1990:

  • 0.45 for exposed walls, floors and ground floors
  • 0.6 for semi-exposed walls
  • 0.25 for roofs
  • plus a requirement that the area of windows should not be more than 15% of the floor area.

Like the 2006 changes, it was predicted that the introduction of these limits would result in a 20% reduction in energy use for heating. A survey by Liverpool John Moores University predicted that the actual figure would actually only be 6% (Johnson, JA “Building Regulations Research Project”).

In the 1995 Building Regulations, insulation standards were cut to the following U-values:

  • 0.45 for exposed walls, floors and ground floors
  • 0.6 for semi-exposed walls and floors
  • 0.25 for roofs
  • the limit on window area was raised to 22.5%

The 2002 regulations reduced the U-values, and made additional elements of the building fabric subject to control. Although there was in practice considerable flexibility and the ability to 'trade off' reductions in one are for increases in another, the 'target' limits became:

  • 0.35 for walls
  • 0.25 for floors
  • 0.20 or 0.25 for pitched roofs (depending on the construction)
  • 0.16 for flat roofs
  • 2.2 for metal framed doors and windows
  • 2.0 for other doors and windows
  • the limit on window area was raised again to 25%

Similar limits were introduced into Scotland in 2002, though with a lower limit of 0.3 or 0.27 for walls, and some other variations.

It was claimed by Government that these measures should cut the heating requirement by 25%[45] compared to the 1995 Regulations. It was subsequently also claimed that they had achieved a 50% cut compared to the 1990 Regulations.[46]

While the u-value ceased being the sole consideration in 2006, u-value limits similar to those in the 2002 regulations still apply, but are no longer sufficient by themselves. The DER, calculated through the Government's Standard Assessment Procedure for Energy Rating of Dwellings (SAP rating), 2005 edition, became the only acceptable calculation method. Calculations using previous versions of SAP had been an optional way of demonstrating compliance since 1991(?).

See also

Template:EnergyPortal

References

  1. ^ [1]
  2. ^ [2]
  3. ^ [3]
  4. ^ [http://www.britishgasnews.co.uk/managed_content/files/pdf/greenCity.pdf
  5. ^ [4]
  6. ^ [5]
  7. ^ [6]
  8. ^ [7]
  9. ^ [8]
  10. ^ DTI
  11. ^ [9]
  12. ^ DTI
  13. ^ DTI
  14. ^ DTI
  15. ^ [10]
  16. ^ [11]
  17. ^ Dwelling Carbon Dioxide Emission Rate
  18. ^ Standard Assessment Procedure for Energy Rating of Dwellings
  19. ^ [12]
  20. ^ Pilkington Energy Efficiency Trust
  21. ^ [13]
  22. ^ Assessment of Energy Efficiency impact of Building Regulations Compliance, prepared by the Building Research Establishment for the Energy Saving Trust / Energy Efficiency Partnership for Homes, published 2004-11-10, accessed 2007-08-09
  23. ^ Part L1 - an investigation into the reasons for poor compliance, Energy Saving Trust, published 2006-05-03, accessed 2007-05-18
  24. ^ London Sustainable Development Commission
  25. ^ [14]
  26. ^ [15]
  27. ^ [16]
  28. ^ [17]
  29. ^ [18]
  30. ^ New Scientist, November 2005
  31. ^ [19]
  32. ^ [20]
  33. ^ [21]
  34. ^ Civic Trust Award
  35. ^ South Yorkshire Energy Centre
  36. ^ [22]
  37. ^ [23]
  38. ^ [24]
  39. ^ [25]
  40. ^ [26]
  41. ^ [27]
  42. ^ [28]
  43. ^ Solar Energy Applications in Houses, F Jäger, ISBN 0-08-027573-7, page 54
  44. ^ The Building Regulations 1976, ISBN 0-11-061676-6, page 96
  45. ^ DTI: Energy efficiency in the UK 1990-2000, pdf file
  46. ^ 2003 Energy White Paper, page 34

Ressourcen

In the media

Technical reports

International

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