In the words of Professor David Mackay, we need "numbers, not adjectives" to compare, understand and manage our country's energy supplies and our own energy demands. In this spirit, here are two charts.
The first shows my family's energy use at home each year from 2006 to 2011. For reasons I have made clear throughout this blog, we used 52% less energy in 2011 than in 2006.
The second chart shows the costs of this energy.
Sticking to Prof. Mackay's injunction, I will simply note that, despite increases in the unit costs we pay for energy over this period, our total bill for energy in 2011 was 38% smaller than we paid in 2006.
There are all sorts of issues, from fuel poverty to carbon emissions, that this comparison does not address. The simple point that it illustrates well, however, is that individual efforts and investments to use energy more efficiently have a real impact on our energy bills. If my family had used as much energy in 2011 as we did in 2006, our bills would have risen by 17% over this period - despite switching to a cheaper supplier at the end of 2008.
And the carbon emissions from our energy use? I calculate that, in 2006, these amounted to 8 Tonnes CO2. In 2011, our annual emissions were down to 3.6 Tonnes CO2. The total reduction over five years (2007 - 11) amounts to 15.7 Tonnes.
This may not sound much compared with, for example, long-haul flights, but we haven't taken any of those in the last five years either. Cutting carbon makes each and every part of life more sustainable, from holidays to heating, from commuting to computing and from diet to DIY. Oh dear, I've forgotten the Professor's advice and slipped into rhetoric so I'd better stop and leave you to do the maths.