October 2010: Chart of the Month

(Looking for the September Chart of the Month? Click here )

At this time of year, everyone is turning the heat on.

I've already written about how we're also turning the heat up. I used some research data from BRE to show that we've been cranking up the thermostat for about 30 years now, and as a result the average temperature inside a British home has gone up from about 13°C in 1970 to about 20°C today. As a result, I said that Britain had gone soft.

But that's only half the story. The truth is, Britain has gone very soft. The part I was missing out is what has happened to the temperature outdoors over the same period.

So guess what? It turns out that, using a more or less accepted method for measuring these things, it is a lot warmer these days than it was 40 years ago - warmer, that is, in the sense of how many days a year you'd need to turn the heating on.

Have a look at the chart below and you'll get the picture. There are about 10-15% fewer heating days per year than when our parents were our age.

Conclusion? We need less heat, but we are using more. If you can figure that one out, please post a comment below.

(Click on the image to enlarge the view.)

The raw data is from the Met Office, although access is only after an authorisation process. And here is a bit more on the methodology for Heating Degree Days. In the chart, I have taken a simple average across all UK weather stations and shown the hi/lo bands in the shaded area.