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Cracking the Code - A guide to the Code for Sustainable Homes

The Code for Sustainable Homes (CfSH) is a framework of legislation that the government has developed to address standards in the housing sector in relation to new build homes.

It would be impossible to go through all the requirements in one article for each of the levels of the CfSH, so I'm not going to try… What we can do is look at a number of the principle areas for each level and some practical advice to keep in mind. Legislation on 'Sustainable Construction' has only just begun and is not going to stop anytime soon.

For those looking to secure future business, an understanding of the requirements and demands of the CfSH, and energy efficient/low carbon building in a wider context, is crucial. Many working in the social housing sector are now very comfortable with Code Level (CL) 3 buildings as they have been mandatory for some time and those who have been reading the recent consultation documents on Part L Building Regulations will have noticed that they are moving to line up with many of the requirements of CL3.

By 2012, social housing will have moved on to CL 4 and the target of 2016 for CL 6 is still firmly in the political sights. There has been much debate on whether the sector will be able to effect wholesale change in such a short time period, but the fact remains that even if the target slips by a few years and the CfSH changes in some of its requirements, the sector as a whole still has to change dramatically.

In this article I am going to look at each code level in turn starting with CL3 which is the current standard in social housing. A Building Regulations change this year will also mean that a lot of the requirements of CL3 will be applicable to any form of housing.

Code Level 3

The 'simple' headlines for compliance are: - 25% reduction of building CO2 emissions relating to energy in the home over 2006 Building Regulations. - Internal potable water use restricted to 105 litres per person per day There are other mandatory requirements relating to all code levels relating to materials, water run-off and site waste.

The key construction aspect to keep in mind with most code levels is the performance of the building envelope and CL3 is no different. An understanding of air tightness, which is largely reliant on attention to detail on site, will help to ensure that the operational energy use is reduced. There are also a number of products that have been developed to address some of the more difficult areas of airtightness. The code works on a points system, so there are many areas where you can 'pick up' points.

For a CL3 house you need to comply with the minimum standards, the headline requirements and achieve 46.7 points in total and 10.3 points are awarded as a base level for the headline points of CO2 reduction and water usage.

The points come from a massive range of areas including:

- Providing cycle storage and drying space

- Energy Efficient Lighting

- Providing a home office

- Reducing water run-off

- Use of environmentally friendly materials

- Ecology reports

It is necessary to work with a qualified Code assessor to ensure that the points are correctly allocated and to sign off the completed project.

Code Level 4

The headline requirements for CL4 are: • 44% CO2 reduction of building CO2 emissions relating to energy in the home over 2006 Building Regulations. • Internal potable water use restricted to 105 litres per person per day The same mandatory requirements in materials, water run-off and site waste are required. The 44% reduction target really starts to challenge the way that we are used to building.

As mentioned under CL3, air tightness is crucial to ensure that the energy that is produced stays in the home. Over 60% of the energy that is produced in buildings in the UK goes straight through the walls. There is a lot of confusion over air tightness in the UK. First thing to establish is that air tightness is a separate issue to ventilation. All homes need to be ventilated, but our walls are not designed to carry out that function!

Another separate issue is breathability, which is all to do with moisture and not air. Insulation is also an important factor, which the sector is getting to grips with. The CO2 reduction calculations are derived by using a tool called SAP.

SAP, which stands for Standard Assessment Procedure, involves the assessor working out a Target Energy Rating (TER) for the dwelling. The next step in the SAP report process sees the assessor calculate the Dwelling Emission Rate (DER). If this is equal to or less than the TER then the SAP rating shows a pass and the SAP calculations are complete.

For a CL4 house you need to comply with the minimum standards, the headline requirements and achieve 54.1 points in total. In CL4 13.9 points are awarded as a base level for the headline points of CO2 reduction and water usage.

Code Level 5

The headline requirements for CL5 are:

• 100% CO2 reduction of building CO2 emissions relating to energy in the home over 2006 Building Regulations.

• Internal potable water use restricted to 80 litres per person per day

The first question is usually - what does 100% reduction actually mean? The key to this is the Building regulations. Building regs cover emissions relating to heating, hot water, ventilation and lighting. Other energy uses in the home such as appliances are not part of this calculation. In effect this 100% increase means that the emissions in these areas should be zero. This can only be achieved by the use of renewable technology. Renewable technology is another area that would fill a number of articles and the Government has now introduced the feed-in tariff to make these technologies more attractive.Whether they are the real answer to the energy problems in the UK is also the subject of much debate.

For a CL5 house you need to comply with the minimum standards, the headline requirements and achieve 60.1 points in total. In CL5 23.9 points are awarded as a base level for the headline points of CO2 reduction and water usage

Code Level 6

The headline requirements for CL6 are:

• Zero Carbon Home

• Internal potable water use restricted to 80 litres per person per day

This is the standard which the government wants to achieve by 2016. The definition of Zero Carbon has also been a subject of much debate and the government has revised the definition of 'Zero Carbon' to make it more achievable.

A zero carbon home is one whose net carbon dioxide emissions, taking account of emissions associated with all energy use in the home, is equal to zero or negative across the year. The definition of 'energy use' will cover both energy uses currently regulated by the Building Regulations and other energy used in the home. There is still much debate on how this can be truly achieved, but again the use of renewable technologies is the only way of compliance.

For a CL6 house you need to comply with the minimum standards, the headline requirements and achieve 64.9 points in total. In CL6 25.1 points are awarded as a base level for the headline points of CO2 reduction and water usage.

There is a long way to go, and the mechanism for getting there will undoubtedly evolve, but there is no question that the age of sustainable construction has begun.

About the Author

John Cave is the Sustainability Director of one of the largest independent building materials distrubuters in the UK, EH Smith.

He has been researching the field of energy efficient construction since 2006 and now works with many of the UK's leading Architects, Contractors and Housebuilders. He also is a Non-Exec Director of the BPVA (British Photovoltaic Association) and the MEBC (Midlands Environmental Business Company) and sits on a number of industry working groups for the Government Department, DECC (Dept. of Energy and Climate Change)

EH Smith have depots in Leicester, Cannock, Birmingham, Solihull, Stourbridge, Sutton Coldfield, Witham (Essex) and Hemel Hempstead and has been trading since 1923.

If you have any queries on any aspect of sustainable construction please contact us on sustainable@ehsmith.co.uk
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