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Green gloss code?April 2007

The Code for Sustainable Homes means that designers will be encouraged to create ultra low energy houses, with renewable energy technologies and water saving features set to become standard practice. James Parker puts the Code into perspective.

Sustainability is rapidly becoming the key issue for new housing. In order to drive the market further into a greener future, the department for Communities and Local Government (CLG) has launched what it calls "A step-change in sustainable home building practice" - Code for Sustainable.

The Code was launched in December 2006, with the technical documents released in April 2007. The Code builds on BRE's EcoHomes system - the domestic version of the BREEAM assessment tool.

The Code works by using a point-scoring assessment method in nine design categories. The points from these categories are added together to arrive at a whole-house star rating. One star is the entry level (a basic sustainable home), with six stars reserved for truly carbon-neutral homes. The levels in between reflect increasingly greener hues of sustainability.

However, house designers must reach the minimum standard of one star in two key categories, energy and CO2, in order to qualify for points in the other seven categories.

Energy and carbon dioxide emissions

Energy and CO2 are based on the Target Emission Rate (TER) as used in Part L of the 2006 Building Regulations. The key measurement is the percentage improvement over the 2006 requirements. This ranges from a 10 percent improvement for the 1 star rating, up to the impressive zero-carbon home for a six-star rating.

As well as the minimum standards, points are awarded for the level of improvement of overall energy use. This is broken down into smaller increments (15 levels).

Other points in this category are awarded for various factors, for which there are no minimum standards. The building fabric is assessed based on the heat loss parameter - a measure on how much heat is lost through walls. Points are available for heat loss values less than 1.3 and more for heat loss values less than 1.1.

Points for dedicated energy-efficient fittings for internal lighting are awarded where the percentage of fixed fittings are greater than 40 percent, with extra points for more than 75 percent.

External lighting is covered with points for energy efficient fittings, as is security lighting of 150 W or less, along with movement or daylight sensors. Points are awarded when at least 10 percent of the energy demand is supplied from local renewable or low carbon energy sources.


Water is the only other category with minimum standards applied to multiple star ratings. The minimum standards are based on the internal potable water consumption in litres per head per day.

In addition to the internal use, extra points are awarded for the recovery and storage of rainwater for external use.


The sustainability of construction materials is measured using the BRE's imminent Green Guide, which will rank the environmental impact of materials using a life-cycle assessment method.

To attain the minimum standard, at least three of the five key construction elements (roof, external walls, upper floor, internal walls and windows and doors) must meet the Green Guide rating of D or better.

Points are awarded based on responsible sourcing of materials as well as the environmental effects. A dedicated materials calculator has been developed for the Code.

Surface water run-off

To meet the minimum standards for surface water run-off, housing developments must not have any detrimental effect on the site run-off compared to previous conditions. This includes both the peak rates and annual volumes of run-off.

Other points are awarded for sustainable urban drainage systems, including peak time attenuation and the placing of houses in an area of low flood risk.


The minimum standard for waste looks at both site waste management and household waste storage. The Code requires a waste management plan on the site, the monitoring of waste and the setting of targets.

Points are awarded for recycling and composting facilities. A management plan for the construction waste also gains points.


There are no minimum standards for the pollution effects of sustainable homes house, only point-scoring features. Points are gained for the use of insulating material that avoid substances that have a global warming potential (gwp) of 5 or more (referenced to CO2 which has a gwp of 1). Points are also awarded for low emissions of nitrous oxide from space heating and hot water systems.

Health and wellbeing

Health and wellbeing effectively means the comfort and live-ability of a new house. Factors assessed are daylight, sound insulation, private space and homes suitable for different stages of life.

With daylighting, points are awarded where minimum average daylight factors are reached for specific rooms. These are at least 2 percent for kitchens and at least 1.5 percent for living rooms, dining rooms and studies. Also, they should be designed to have a view of the sky.

To gain points for sound insulation, it must be proved that the standard of sound insulation is high than that
prescribed in Part E of the Building Regulations.

Points are also awarded for complying with the standards of the Lifetime Homes scheme, which looks at the potential of homes to cope with the lifetime requirements of the occupant, such as adaptability for increasing levels of disability.


Management covers both construction and post construction management. On the construction side, points are awarded for membership of the Considerate Constructors Scheme and on a commitment and strategy to reduce the harmful effects of construction on the site environment.

Points are gained for the provision of Home User Guides, which are relevant to the operation, and environmental performance of the home.


The last category, ecology, looks at the effects of house building on existing flora and fauna. Points are gained for building on land with a low ecological value, adding ecological enhancements, protection of ecological features, and minor or positive changes in the ecological value of the site.

Supporting documents

The technical documentation is due to be published by April this year, and will include a calculation and assessment tool.

The calculation tool will link to existing methods, which will provide some consistency across regulatory requirements. For example, the energy calculation will follow the same methodology for the system of energy performance certificates to be introduced in June 2007 as part of the UK's commitment to implement the Energy Performance of Buildings Directive (EPBD).

The Code will also share a common calculation tool for water efficiency with that being developed for the Building Regulations. This tool is already out for consultation.

BRE will train assessors for the Code. This will be similar to the BREEAM/EcoHomes training schemes. Assessors already accredited to carry out EcoHomes assessments will be re-trained through top-up courses.

While the Code is not mandatory, developers will be encouraged to follow it. The government is considering making the Code mandatory, possibly 2008 with the next changes to the Building Regulations. However, government-backed housing, such as those built for the Housing Corporation or English Partnerships, with have to reach set levels of the code.

Local authorities, many of which are currently working on new Local Development Frameworks, may also require certain levels to be met on some developments. BSRIA's experience has revealed that certain councils are already asking for EcoHomes assessments.

Mandatory or not, the Code is a step forward in an area of construction. Hopefully, the Code will have the desired effect of encouraging the take up of more sustainable practices and products by house builders.

The Code will have a knock-on effect across the industry, not just house builders, but materials manufacturers and suppliers and especially manufacturers of energy related products. Some will find their business increasing, while those with less environmentally-beneficial products will be left behind.

For more information contact Design & FM Innovation at BSRIA:

Tel: +44 (0) 1344 465600