Humpty Dumpty, Zero Carbon Homes and public confusion

The National House-Building Council Foundation, which is an independent research institution, connected to the NHBC, but operating separately and works closely with the Building Research Establishment, to look at the Government’s target of all new homes being “zero carbon” by 2016. 

The definition of a Zero Carbon Home is a bit of a Humpty Dumpty definition. In Lewis Carroll’s “Through the Looking Glass” Alice meets Humpty Dumpty who says to her:- 

When I use a word,” Humpty Dumpty said, in a rather scornful tone, “it means just what I choose it to mean - neither more nor less.”  

Zero Carbon Homes convey a concept of a home emitting no net carbon dioxide but the reality of the definition is very different.

All homes will emit some carbon dioxide unless the occupants live simple lives in caves uncomplicated by modern conveniences and luxuries. Achieving low carbon emitting homes is perfectly possible as things are now, and would be an honest description of what we can achieve, instead of claiming that we are about to find the Holy Grail. 

Still, the NHBC Foundation has to work with that Humpty Dumpty definition and do their research accordingly. The have found that people feel that Zero Carbon Homes would cost more, need extra maintenance and that they would have to cut back on appliances.  

I shall examine these three matters, cost, maintenance and cut back on appliances, from the energy point of view. Things like insulation, tight building, and design are pretty well established and builders and the public know about the benefits of these things. 

Cost

Will Zero Carbon Homes cost more? Well, I think that depends on the definition of “cost”. There is a greater initial capital cost if you install, for example, solar heating into a new home. If you install a simple solar water heating system the initial capital cost will be around an additional £2,500 for a state of the art system, which is significantly less than the cost of installing a system in an existing house, where the cost is around £4,500.  

The same principles apply if the house includes solar central heating support as well as a hot water system – the figures are proportionately higher. It is much cheaper to install the solar system as the home is being built; the scaffolding costs are saved and some roof tiling costs are saved; it is much easier for plumbers to work in a house that is under construction, than in an occupied house, making the work take less time.  

What happens to cost after this really depends on how house builders treat the solar system. If they regard it as an optional extra, like a power shower or a top of the range kitchen, they will add a significant margin; if the solar system is treated as a requirement there is no need to add a large margin – they do not do so with bricks and mortar. 

However they treat the cost, the initial capital cost will be there and will have to be paid for. At £2,500 the additional mortgage payments on this amount will be less than the annual financial heating savings, and the system will soon pay for itself making the house actually cheaper to buy. 

You can make similar calculations about other forms of microgeneration. Photovoltaics cells which generate electricity are much more expensive than solar heating; you will not be in positive financial territory, unless existing energy prices rise through the roof, so as to speak.

Heat pumps in off gas grid network places, will like solar thermal systems be cheaper to install than not to install. The jury is still out on small scale wind turbines and other forms of microgeneration. 

So the people interviewed for the NHBC’s research fearing increased costs were in most cases wrong. Paying less on your mortgage than you save on your energy bill seems, to me, a bit of a “no brainer”. People just need to understand that is what will happen. 

Maintenance 

The maintenance of microgeneration appliances varies. Photovoltaics require no maintenance, except that as the electricity generated is Direct Current it has to be inverted into Alternating Current. The inverters will wear out and will need to be replaced and I think that is the only maintenance that PV needs. 

Heat pumps do need maintenance whether they are air source or ground source. The pumps themselves wear out, fans need new bearings and in some cases the subsoil must be regenerated with heat to prevent long term damage. Also, all the other maintenance requirements of a heating system – valves radiators pumps etc still have to be taken care of. 

In homes, solar heating systems require very little maintenance. The panels themselves (in modern systems) do not need anything doing to them; treat them just as you would a new roof. The pumping station uses a similar pump to a central heating system and if this is high quality will be unlikely to need changing for ten years or more. The glycol should be tested every ten years; if it needs to be replaced then that is a simple and inexpensive process. 

Of course, solar thermal heat operates with some fossil fuel back up. The fossil fuel heating system will work less hard with a solar system, parts will wear out more slowly and there will be much lower maintenance costs, so overall solar thermal systems are very low maintenance. 

Again, this is just a case of public perception. There are not enough solar systems in the country for people to understand these points – yet, but as they do they will find that there is nothing to fear from the costs of maintaining microgeneration systems. 

Lifestyle and Appliances 

This is the core of the beast, the essential conundrum that has to be solved if we are to significantly reduce carbon dioxide emissions which are likely irreversibly change the fundamental inter-relationships of life on earth.  

We must not get confused in the case of homes and it is worth understanding how homes use energy. 24% of household energy is spent on water heating and 60% on space heating. 3% is used for cooking and 13% for electricity mainly for appliances and lighting. 

Of course, confusion about the definition of Zero Carbon Homes leads to confusion about lifestyles. People seem to think that “Zero Carbon” affects the 13% electricity use, rather than the high energy uses of water and space heating.

It is a natural enough confusion because if you have a Humpty Dumpty definition you will find people taking its meaning at face value, rather than at Humpty Dumpty’s value.It is clear that we should be concentrating on lower carbon homes for new homes, picking out the easiest and most cost effective measures which do not initially affect people’s lifestyles.  

My Low Carbon Home Policy 

Taking the overall way in which new house building energy regulations should be drafted it is to me perfectly clear: 

• Solar water heating should be mandatory for all new homes; it’s a no brainer. The average system will save at least a half of the 24% energy spend on water heating, and up to 70% if high quality systems are installed. Whatever you do with insulation you still need some form of energy to heat water.
• Solar space heating support should be rewarded; here the potential is to save around half of the 60% if builders use underfloor heating and design homes to take larger cylinders to store the heat. These figures will probably change for the betters as new homes are built with better insulation and better design. Some new homes may need very little space heat.
• Gas should be connected to all new homes, if possible; gas for home heating creates about a third of the emissions of electricity and around 40% of the emissions of oil and liquid petroleum gas.
• Where gas is not available easily, the heat pumps should be considered for space heat, with solar thermal for water heating; excess solar thermal heat in summer can be used to regenerate the subsoil.

None of these suggestions involve deploying rocket science and all are be easy to adopt. Some countries have already adopted them.

The house builders will be able to follow these rules and the additional installations will cause prices for the kit and prices for installation to fall. These rules would do far more to help the environment and protect the planet than banning plastic bags or installing low energy lighting.  

The easiest and most cost effective place to start applying the principles of low carbon homes that i suggest is in new build, but this must also be augmented by a clearer policy to “low carbonise” the existing housing stock, which presents a much larger problem.  

We should not have “Zero Carbon Home” concept, but a “Low Carbon Home” in which people can be assured that their lifestyle choices are still respected but that their homes are genuinely helping reduce carbon dioxide emissions. That way we will alsocachieve greater  reductions in emissions at a lower cost than by a confused Zero Carbon concept.