More on the consumption

The progress on the light to indicate energy consumption is going steady, but the camera ran out of juice, so I can't put a picture online. Maybe tomorrow.
So I decided to report to you about the consumption curves.
In the picture you can see a plot of the gas consumption versus the average monthly temperature for the last 3 years - 2006, 2007 and 2008. The "trendlline" is a excel computed trendline, and its equation for 2006 is my basis for the energy saving calculations.
In 2006 I did' have in place any energy saving measures for the heating, and a sinple manual thermostat, so I consider that to be the baseline against which all gains are to be measured.
I think the line approaches quite well the measured results. It is a second order polynomial equation.
Also in the graphic is the date for 2007, when my automated zone controlled system was already in place.it;s line is quite deviated from the line of 2006, so I can safely assume that there have been some considerable savings, and that my calculations might be close to the real thing.
As for the data points referring to 2008, these come quite close to the predication from the trendline for 2007, apart from the 2 slightly removed dots at the right. These correspond to February, when we spent a week off and therefore saved quite a bit on the heating bill, and December, when most of the roof insulation was already in place! Which makes me very hopeful that the insulation really is doing its job and saving quite some gas and CO2 from going up into the atmosphere!
Byt the way, for January, which just finished, I got a saving of 40% with respect to the 2006 equation, whereas in January 2008 and 2007 the saving in January was only about 12%.
I am hopeful to see what the coming months bring, with the added sun exposure hours (they do make a difference)!
I'll keep posting about it!