The code for sustainable homes

The Code for Sustainable Homes is the government’s national standard for the sustainable design and construction of new homes. Introduced in 2006, the Code is a voluntary standard, but one that is often cited as a mandatory requirement by planners and commissioners of social housing. Reducing carbon emissions from homes is at the centre of the Code for Sustainable Homes. As such, it’s an important tool for the government to achieve its ambition of all new homes meeting a zero carbon standard by 2016. In the longer term the Code forms part of the framework for delivering on the UK’s legally binding target of an 80 per cent cut in carbon emissions by 2050.

How does the code work?
The Code for Sustainable Homes gives new homes a Code rating from one to six, with six being the most sustainable. Homes are rated by trained and accredited assessors, based on a scoring of a wide variety of different sustainability features. Within the Code, standards may be compulsory or voluntary.

To reach level 3 of the Code for Sustainable Homes, for example, developers must reach the following minimum standards:

• Achieve 25 per cent reduction in carbon emissions from energy use in the home, compared to a similar home built to the building regulations

• Install water saving measures like low flow taps with the aim of achieving a maximum usage of 105 litres per day

• Ensure effective surface water management around the home

• Ensuring construction waste is properly disposed of, and that the wider environmental impact of the construction materials is reduced.

Beyond reaching these minimum standards, to hit Level 3, the builder also has to attain a score by choosing from a range of voluntary measures, such as by providing:

• More energy efficient lighting

• Cycle storage

• A home office

• Recycling facilities

• Enhanced home security

• Enhanced sound insulation.

(source: Code for Sustainable Homes, Communities and Local Government, Dec 2006)

Promoting sustainable housing
How does the Code for Sustainable Homes promote sustainable housing? The Code for Sustainable Homes interprets housing sustainability very widely. Issues tackled range from minimising homes’ impact on the local ecology, to promoting ‘lifetime homes’ (usable without adaptation by people with mobility problems).

But climate change is the issue at the heart of the Code. Over a quarter of the UK’s total carbon emissions come from heating and electricity use in our homes. The main compulsory elements of the Code for Sustainable Homes are designed to reduce that impact.  

The Code requires energy efficiency and – at higher levels – renewable energy measures to be fitted to homes. The picture shows a home from the Midstreet development in Rochester, built to Code Level 5. The house doesn’t look very different from a normal newbuild home: the builder has mirrored the predominantly red-brick Victorian architecture of the surrounding village. But despite its appearance, this property boasts a combination of advanced green features. Photovoltaic panels provide much of the electricity that’s used in the home. A biomass wood-chip boiler provides heating. And overall heat demand is kept to a minimum with triple-glazed windows, and walls made out of pre-fabricated highly insulated panels.

The Midstreet home, will still – over the course of a year – take some energy from the national grid. At level 6 of the Code, though, homes have to meet a zero carbon standard whereby the home is required to generate more clean renewable energy annually than its draws from the grid.

There are also other climate change measures promoted in the Code which do not link to direct home energy use. The Code requires builders to pay attention to carbon emitted from the production of the building materials they use. It also encourages architects to include cycle storage in designs – helping to reduce greenhouse gas emissions from car use.

Standards for water use are another important element. For high levels of the Code, it suggests that residents should use less than 80 litres of water per day – down from our current average of 150 litres per home. This can be achieved, for example, by fitting low flow taps and aerated shower heads. In areas of rising population and more limited rainfall, like the south east of England, this water use standard helps reduce the risk of serious water shortages. Reducing water use in new homes is also important to address carbon emissions. In the majority of current homes, most of the energy use goes on keeping the home warm. Highly energy efficient new homes, though, don’t lose much heat through walls and windows. Much more energy is used (and therefore carbon emitted) from heating water rather than space heating. 

What success is the code having?
Most homes built to the Standards of the Code for Sustainable Homes have been built for social housing providers. The government’s Homes and Communities Agency has required that all homes built with its funding should meet at least Code Level 3. 

But the longer term aim of the Code is not just to sell to large scale buyers of housing. It’s also intended to influence individuals and families buying houses.

Ensuring the customer demand for high Code level homes depends on the marketing efforts of house builders. The Energy Saving Trust has researched how to make this marketing a success. We believe developers need to highlight to buyers the direct, personal benefits of more sustainable homes. For example, homes that are highly energy efficient and use renewable energy have much lower bills. They’re more comfortable: less draughty and it’s much easier to control their temperature. Emphasising these very tangible benefits – which have nothing directly to do with the environment – will be vital in persuading most home buyers to choose sustainable homes.

The future of the code
A Consultation on changes to the Code for Sustainable Homes was issued in the last days of the Labour government. Among other things, the consultation sought to align the Code for Sustainable Homes with the future 2016 zero carbon standard that all new homes will have to reach. 

The Code for Sustainable Homes is an important part of the government roadmap to achieve a low carbon transformation of house building. Building social housing to Code Level 3 has undoubtedly helped prepare the developers for the ambitious leap they will have to make to full zero carbon new homes in England.
   
In the longer term, post 2016, the Code will continue to have a role in promoting wider sustainability beyond the carbon emissions from direct energy use. The issues in the Code relating to water use, sustainability of building materials and low carbon transport will continue to be important sustainability challenges for the industry.
   
Finally, eighty-five percent of the homes that we will be using in 2050 have already been built. With the Code, we are strengthening the capacity of our building industry to construct very low carbon new homes. That can only help them prepare for the much bigger challenge of making our existing homes fully fit for a low carbon future.

What is a zero carbon home
The basic concept of a zero carbon home might seem simple – a home that replaces any grid electricity it uses over a year with at least the same amount of clean renewable energy generated on or near the home. The Code for Sustainable Homes had included this concept as part of Code Level 6.
   
However such a simple definition poses a problem. For some types of home it can be difficult and expensive to fit renewable energy measures. Blocks of flats in towns can be much harder to fit with measures like solar panels or wind turbines than large detached homes in the country.
   
To overcome this problem, the government has proposed that developers of zero carbon homes need only achieve part of their 100 per cent zero carbon target on the home or development itself. They will also be able to claim carbon reductions they have achieved elsewhere. Thus, improving the insulation of a nearby old home could count towards making a developer’s new homes zero carbon. It is this more complex definition – of on-site carbon reduction plus off-site carbon saving measures – that forms the 2016 Zero Carbon Definition.