The Path to Zero Carbon

ABOVE: Not Rated - A house built to comply with Building Regulations standards just three years ago wouldn’t get a rating in the Code for Sustainable Homes, despite the inclusion of a condensing boiler with weather compensation, high levels of insulation and underfloor heating.Read more about this project.

As of April 2008 all new planning applications in England will have to ‘reference’ the Code for Sustainable Homes (CSH). The Code sets out a star rating from 1 to 6, where 1 represents a slight improvement on Part L of the Building Regulations and 6 is zero carbon, which will be mandatory for all new houses from 2016.

The effect of this requirement to ‘reference’ the Code is that it will become necessary to assess the property against the Code and to achieve a star rating. Some authorities, notably Gloucestershire, Nottingham and some London boroughs, are requiring that a minimum 3-star rating be achieved.

Since 2005 a number of authorities have applied what has become known as ‘The Merton Rule’, which requires that major developments must generate a minimum of 10% of the site’s energy from renewable sources. ‘Major’ is generally taken to be two dwellings or more (specifically to allow self-builders to be excluded) but increasingly this rule is being applied to all new properties. The rationale being that by 2016 the zero-carbon rule will apply to all new houses and therefore we may as well start now. The 10% aspect of this rule is also in flux. Some authorities do not apply it at all and some require up to 25%.

The interesting point is that a 3-star rating under the Code will require a minimum of 25% improvement on Part L Building Regulations. But it also requires a number of other things. Reaching 3-star standard imposes a maximum water use of 105 litres per person per day. To put that in perspective, the average UK home currently uses 150 litres per person per day. In addition, the self-builder will, amongst other things, have to make substantial improvements in sustainability of the materials used, install sustainable drainage, limit surface water run-off, control pollution, and minimise the home’s ecological impact.

Reaching the 25% improvement in energy use is a stiff target and starts with reducing the energy demand with low- energy fittings, improved insulation and improved airtightness. All of these are covered under the Code but will still leave the homebuilder with the need to generate energy on site.

So what do we do?

Grasp the opportunity. It can be argued that this generation never had it so good and has had all the benefits of ‘the white heat of technology’. For 50 years we have had cheap energy and cheap materials and have been indiscriminate in our use of them. Perhaps we now have to take the opportunity to put things right.

The instruments the Government is using to move us towards its targets are the Code, the Building Regulations and planning regulations. Examination of these documents show that none of what is being required is particularly new. Planning Policy Statement 1 (PPS1), published in 2005, states that developments should address climate change through policies to reduce energy use, minimise emissions and promote renewable energy resources, and take climate change into account in the location and design of the development. PPS22, published in 2004, requires authorities to implement polices that require a percentage of the energy used in new residential properties to come from renewable sources. The Merton Rule springs from this regulation. The Code was first published in 2006 and Building Regulations are continually under review. Part L particularly has been ratcheting up since the 1990s.

It was Margaret Thatcher in 1984 who first used the expression ‘global warming’ as a defence to the closing of coal mines. So none of this should come as a surprise and it is probably too late to kick against the bricks.

This is a self-build magazine and obviously we concern ourselves with the individual homes that our readers are building. It has to be said that these changes apply across the housebuilding industry and that self-builders have been rather caught in the net. Self-builds account for over 10% of new houses built each year so it is perhaps reasonable that they be included. The options seem to be to grasp the nettle and see this as an opportunity to build better houses — better that, surely, than rail against the inevitability of change.

As Bob Dylan said: If your time to you is worth savin’/Then you better start swimmin’/Or you’ll sink like a stone/For the times they are a-changin.

Code for Sustainable Homes - Ratings

LEVEL 6: Potton's Lighthouse

Potton’s latest option is designed to achieve Level 6 of the CSH. It uses a highly air-tight SIPs system giving Uvalues of 0.11. Rainwater harvesting, solar hot water, lowenergy lighting, and mechanical heat recovery and ventilation combine with a biomass boiler and PV array to meet the standard, resulting in estimated annual energy bills of just £30. www.lighthousebypotton.co.uk  

LEVEL 3: A Green German Timber Frame Home

German timber frame package supplier Baufritz is a real pioneer in its field, building houses with 400mm-thick walls insulated with wood shavings that have been generated during the frame’s manufacturing process. Baufritz also places great emphasis on the sustainability of its manufacturing process and the embodied energy within its building materials.

To achieve zero-carbon status as defined by the Code for Sustainable Homes, however, there is a need to rely on microgeneration technologies on site — such as solar power, wind power or heat pumps. According to Baufritz, “This over reliance on technology means that should any failure occur in a (CSH-defined) zero-carbon home, it would immediately become carbon negative.”

Without the addition of microgenerative features on site, this super-airtight home – one of the greenest in Britain – would perhaps achieve a Level 3 status. Read more about this house

Further reading:

• A Few Facts About the Code for Sustainable Homes
• How to Achieve Level 3 of the Code for Sustainable Homes
• A Super Insulated Self Build With No Central Heating

Read more of sustainable building expert Tim Pullen's views in his blog