Zero Carbon Homes

Is There Such a Thing as a Zero Carbon Home?
With a quarter of all carbon emissions said to be emanating from our homes, ‘zero carbon homes’ have become a talking point in the construction sector. Indeed, Gordon Brown recently unveiled plans to build more than 100,000 carbon neutral homes to help first-time buyers get on to the property ladder.
Following a government statement that it wants all builders to provide carbon-free homes by 2016, near zero-emission houses by builders Stewart Milne, Kingspan, ecoTECH and Hanson were recently built to the Code for Sustainable Homes, the first to be assessed under the new voluntary regulation. Stewart Milne has said that, by building homes in a way which was more thermally efficient, his firm could achieve 70% to 80% of the zero carbon target, with the remaining 20% to 30% coming from micro-renewables such as wind generation and solar panels.

In a world of finite resources, few of us would argue with the logic of using sustainable materials and renewable energy sources within house building where possible. Nevertheless, the ‘zero carbon home’ is presently being used as a marketing tool by some house builders seeking to distinguish their homes from those of their competitors.

Yet, in practice, it is common knowledge that, rather than their home providing a ‘zero carbon footprint’, the three most important criteria upon which most house-hunters base their home-buying decision are location, location and location. Once house-hunters have determined on a favoured location, then a whole host of other considerations will come into play, including price, proximity to school/workplace and, of course, the condition of the property.

Perhaps whether or not a property can offer a ‘zero carbon footprint’ will, over the coming years, become one of these considerations but, even so, it is unlikely that it will supplant the dominance of the prime consideration of location.

Nevertheless, the creation of prototype ‘zero-emission’ homes by various house builders raises the question of whether house-hunters will be prepared to pay more for such a product than for a home built by traditional building methods and materials? Whilst, theoretically, some house-hunters might be prepared to pay more for a carbon neutral home in the expectation that it will have less expensive running costs over the duration of its habitation, that theory has yet to be put to the test.

But just as ‘environmentally friendly’ is a term loaded with ambiguity, so can ‘carbon neutrality’ mean different things to different people. If we assume that by a ‘zero carbon home’ we mean a property that can be inhabited without creating carbon, then, reducing energy use by, for example, improving insulation, homes can be made more ‘carbon efficient’ if not quite ‘carbon neutral’.

Yet this simplistic definition of a ‘zero carbon home’ fails to take into consideration the significant amount of carbon produced in the process of constructing a home. Many traditional building materials, such as cement and breeze blocks, use up significant amounts of carbon in the manufacturing process, and much carbon is consumed in the transportation of these materials to building sites throughout the UK.

Consequently, any accurate measure of a home’s ‘carbon neutrality’ should take into account the materials used in its construction and the methods of transporting these materials to the building site, as well as any carbon created through its habitation.

Whilst the debate about ‘zero carbon homes’ has focused chiefly on newly built homes, the fact that second hand or ‘pre-owned’ homes constitute a significant proportion of the housing market cannot be ignored. Although the refurbishment required to convert an existing home into a ‘carbon neutral’ home could be comprehensive and costly, one benefit of such a conversion is that the carbon expended on its construction has been spent already. This means that no further carbon need be expended on the manufacture or transportation of building materials.

At present, the ‘zero carbon home’ remains a target for house builders to strive towards rather than a reality. Yet whilst a proportion of house-hunters might place ‘carbon neutrality’ high on their list of criteria in their house-buying decision, since location will remain their prime consideration, it is government regulations requiring house builders to reduce the amounts of carbon produced in the construction process that is likely to be the chief driver towards zero carbon homes.

Reproduced by kind permission of:
Andrew McFarlane is a Partner in DM Hall, Chartered Surveyors, and a specialist in building surveying (andrew.mcfarlane@dmhall.co.uk)