Zero Carbon Homes

It’s a nice catchy phrase, “zero carbon homes” but what does it mean? The phrase was invented by a Government Minister as a short pithy explanation of a policy which was to ensure that one day in the near future all United Kingdom homes that were built would be built in such a way so that the homes, when occupied would not emit any carbon dioxide. At first sight it sounds like a good policy, but when you think about it, it is deeply flawed as a policy; it is really not possible to design a home where all the energy used by its occupants when they occupy it is produced without producing carbon emissions.

Certainly the home can be designed to be a low user of energy, which will save plenty of emissions. It can be built to very airtight, high insulation standards, so that there is very little call for space heat. There might be health issues on building too airtight a home, and this needs to be very carefully considered. It can power its electricity by wind or solar energy, and can heat its water by solar panels. These are not 100% solutions. The wind does not blow constantly and there is night, when the best solar panels will not work.

Storing electricity cannot be done in a way that is environmentally friendly, although heat from solar panels can be stored, there will not produce much heat in winter when daylight hours are short. I know that the government has experimented with biomass; you can burn biomass to produce electricity and heat by using a Sterling engine or Combined Heat and Power device, although the heat is produced as a waste product in summer when there is no call for heat. That means dumping the heat in summer, which you have created by burning biomass. In any event burning biomass is not carbon neutral, but is an excellent way of pumping carbon dioxide into the atmosphere.

Biomass supporters claim that the carbon expelled by burning biomass is offset by carbon stored in new growth. They are wrong; it is not as simple as that. First, when you burn anything, including biomass the carbon dioxide created stays in the atmosphere for a hundred years or so. It is extremely unlikely that the new growth with remain for a hundred years and it is also unlikely that the new growth with sequestrate all the carbon dioxide emitted by large scale biomass burning.

We would need to create huge forests in order to achieve anything like a biomass balance and I see no government policy for this. No, we will simply import most of the biomass, probably from Russia, Canada and Scandinavia, and the cost of importing biomass, in carbon dioxide emission terms. Biomass is usually reduced into small pellets. It is very bulky compared coal, oil and gas, in relation to the energy it produces. You need a large volume of biomass to produce the same energy that a small volume of fossil fuel will produce. That means that there will be an expensive transport and storage bill for biomass, in terms of carbon emissions and in money terms.

There are also concerns, real concerns, about the lowering of air quality that biomass burning will almost certainly bring.

The Housing Minister is Margret Beckett who has said “Climate change is one of the biggest challenges facing the world, and introducing zero carbon homes is an important part of our plans to tackle this”. She said these words when launching a consultation to discover what is exactly meant by a Zero Carbon Home. The consultation has already removed cooking and electrical appliances from the definition of Zero Carbon Homes, concentrating only on the matters covered by existing building regulations, so the definition becomes even more misleading than when it was first announced.

The idea is to allow house builders to choose from a list of “allowable solutions”. Some of the suggested solutions are quite sensible; smart energy controls, insulation and the like are already available. Curiously solar thermal does not yet appear on the list which is a foolish omission; why burn anything when you can heat water using sunlight?

If you read the consultation document at you might feel that there seems to be plenty of back tracking on what should constitute a Zero Carbon Home. It seems likely that property developers will, when they get planning permission, pay for some wind turbines or other means of renewable energy nearby, or in another county or even in another country. That does not make the homes they build Zero Carbon.

It seems that the Government is trying to be able to boast that new homes will by 2016 be Zero Carbon, by introducing other measures, not related to new home building, which should be done in any event, as part of a low carbon energy economy. This will lead to double counting and double boasting. Unfortunately it will not make a difference in emission terms. I would prefer that the Government called the new homes “very low carbon homes”. It would be more honest and would actually explain what is happening.

What should a very low carbon home have as its features? Certainly the Government will not adopt of of the designs that it used recently when building the MPs office opposite the Houses of Parliament, or the Scottish and Welsh Assembly buildings. These are high carbon buildings. For very low carbon homes you have to not have allowable solutions but mandatory minimum requirements, with rewards for doing more.

I suggest these are good starting points for a list of what should be mandated.

1. Thermal solar panels for water and space heating feeding under floor heating

2. Photovoltaic panels feeding into the grid

3. High insulations standards, but not too air tight; people and buildings both need to breathe

4. South facing roofs

5. Very small patios and drives designed to allow surface water to drain through them

6. Brown water recovery systems

7. Smart meters and smart energy controls

8. Small garages for small cars

9. Large gardens

10. The fabric should be built of wood, which will store carbon rather than cement which is made creating large amounts of carbon.

I suppose that the concept of a Zero Carbon Home, however deeply flawed, is too embedded in Government propaganda to be changed. I would much prefer attaining what is possible, rather than what is impossible, and measuring the emissions from homes without including reductions off site. That would be more honest, and we need honesty about what we are really doing to alleviate climate change. The figure that you cannot spin is the amount of carbon dioxide in the atmosphere. No matter how many grandiose schemes and concepts you have, they will all fail unless atmospheric concentrations of carbon dioxide and all other green house gases fall.