Diary Of An Eco-Builder

If we understood the amount of power we were using, we would cut our consumption
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The Independent Online

Although our contemporary world is increasingly obsessed with energy supply and energy efficiency, our collective grasp of exactly what is going on in our domestic wires remains extraordinarily weak. Can you describe a kilowatt-hour and its relationship to all the lights and gizmos you turn on and off in your home?

Our confusion about electricity consumption could easily be overcome with the help of some clever low-powered technology. Imagine if you had a discreet control panel in your kitchen where you could find out how much electricity every appliance and light circuit in the house was consuming at that moment, complemented by tiny ambient indicators in every major room (perhaps above the light switches) that changed colour according to the overall energy consumption of the house.

Imagine if all this information were digitally recorded and turned into a computer-based analysis that made very clear, in units of your choice (cups of tea?), exactly how your house performed over the weeks and months and what differences your choices within it actually made. There is already good research evidence to show that such feedback could lead to cuts in power consumption of between 10 and 20 per cent.

Although such a product does not currently exist, this may be about to change. With the support of Powergen, I have just begun work with Luke Nicholson and Ben Pirt, of More Associates (www.moreassociates.com), to develop a system for Tree House to the specification described above. Their experience of designing user-friendly energy feedback systems in commercial environments should be invaluable in tackling the relatively uncharted territory of the British living room.

It might seem odd to develop such a system for a house that will be ultra-efficient, but we hope to use the house as a test bed for developing energy feedback products. The energy map of Tree House will also be available online, enabling anyone not only to find out what we are up to, but also to transpose their own lights and appliances with ours and see what difference this makes.

You might also think it odd that a power company wants to invest in reducing demand for its product, but all electricity suppliers are required to do this by law. This Energy Efficiency Commitment is achieved by insulating homes and encouraging use of more efficient appliances (Powergen energy efficiency line 0500 20 10 00, www.energyefficiency.powergen.co.uk) or phone the Energy Saving Trust (0845 727 7200, www.est.org.uk).

How are you faring with kilowatt-hours? The problem here is the lack of a clear unit of energy. Usually, we begin with a unit - gallons, calories, doughnuts - then define a rate against it: miles per gallon, calories per meal, doughnuts per day. For electricity, we begin with a rate of consumption, the watt, then create a clumsy unit of energy with it: one kilowatt-hour of energy is expended by a kilowatt (1,000 watt) fire in one hour.

It makes more sense to begin by focusing on the basic unit of energy that the watt itself describes: the joule (named after an English brewer not a French scientist). One watt is a rate of energy consumption of one joule per second (J/s). So one kilowatt-hour of energy is actually 1,000 x 1 (J/s) x 3,600 (seconds in an hour), which equals 3,600,000 joules or 3.6 megajoules. Perhaps if we all worked in scary megajoules rather than wimpy kilowatt-hours, we might take our power consumption a little more seriously. Anyone fancy a pint?