Energy efficiency in British housing

Energy efficiency in British housing has been attracting greater attention in recent years due to the UK commitment to the United Kingdom Climate Change Programme, and the Kyoto Protocol.

Domestic housing in the United Kingdom is currently one of the major obstacles to achieving the 20% overall cut in UK carbon emissions targeted by the Government for 2010.

Housing accounts for around 30% of all the UK's carbon dioxide emissions (up from 26.42% in 1990 By 2010 they are expected to have risen 18.5% above 1990 levels Select Committee on Environmental Audit noted that emissions from housing could constitute over 55% of the UK's target for carbon emissions in 2050 [http://www.publications.parliament.uk/pa/cm200405/cmselect/cmenvaud/135/13507.htm#a23" target="_blank" >^*.

Domestic energy use

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.

In 2004 housing accounted for 30.23% of all energy use in the UK (up from 27.70% in 1990) DTI.

At the same time as 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 (DTI), leading in turn to a rise in the average temperature within them (from 12.1°C to 18.20°C) (DTI). 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 were:

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%)

source: (DTI)

Building Regulations

Energy efficiency in housing was given little thought until the 1973 oil crisis, and there were no regulations in force requiring any energy efficiency measures to be taken until 1979. The 1979 Building Regulations put in place a limit 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.

2006 changes

The energy policy of the United Kingdom through the 2003 White Paper 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), 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).

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 For example, a 2005 study sponsored by the ^*." target="_blank" >There are also concerns about enforcement, with a Building Research Establishment study indicating that 60% of new homes do not conform to existing regulations [http://www.guardian.co.uk/climatechange/story/0,12374,1530811,00.html.

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, 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%.

2010 review

The Government have signalled a further review of energy performance standards in 2010 ^*.

Energy labelling

From June 2007, all homes (and other buildings) in the UK must undergo Energy Performance Certification before they are sold or let ^*, in order to meet the requirements of the European Energy Performance of Buildings Directive (Directive 2002/91/EC). 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.

For new building, SAP 2005 calculations are to form the basis for the certification, while the National Homes Energy Rating scheme (NHER) will be used to assess existing properties.

Other rating schemes

One other 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.

Grants

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.

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 put in place measures to improve the energy efficiency of all residential accommodation in their areas. It was expected that this would result in a 30% cut in energy usage between 1996 and 2010. An overall improvement of 14.7% was reported to DEFRA for the year ending March 2004 ^*.

In May 2006, a report commissioned by British Gas was published, which showed for the first time annual carbon emissions for housing by local authority area. Properties in Uttlesford produced the highest carbon emissions (8,092 kg of carbon dioxide per dwelling). This was 250% higher than than Camden (averaging 3,255 kg), which had the lowest. Among the 23 towns included, Reading had the highest emissions (6,189 kg), with Hull the lowest (4,395 kg). ^*

Demonstration and pioneering projects

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), an environmentally-friendly 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%.

International comparisons

International comparisons of particular note include:

The SBN-80 (Svensk Bygg Norm) 1980 Swedish Building Standards (the first to set demanding energy efficiency requirements), which in 1983 was in advance of the UK 2002 standards ^*

The voluntary Canadian R-2000 standard, to which around 14,000 houses had been built in the 10 years to 1992 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 [http://r2000.chba.ca/Why_buy_an_R2000_home/energy_efficiency.php.

The voluntary German Passiv Haus 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 5,000 such houses have been built across several European countries ^*.

Historic Building Regulations energy efficiency requirements

The u-value limits introduced in 1979 were:

1.0 for exposed walls, floors and non-solid ground and exposed floors
1.7 for semi-exposed walls
0.6 for roofs

1985 saw the first 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
?.? 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. A survey by Liverpool John Moores University predicted that the actual figure would actually only 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 estimated at the time that these measures should cut the heating requirement by 25% (DTI: Energy efficiency in the UK 1990-2000, pdf file).

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(?).

External links

Resources

In the media

May 2006, The Independent, Nuclear power? It's time the Government started getting serious about energy efficiency
July 2005, The Guardian, Energy-saving targets scrapped for housing
March 2005, BBC, Call to demolish polluting homes

International

Energy efficiency in Danish housing

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