This presentation was given to a meeting of the South Essex Area of the Institution of Mechanical Engineers.
It is a substantial update of http://cms.energypolicy.co.uk/heat/268 and has much more information than http://cms.energypolicy.co.uk/heat/269
As before, the data for each year is based on up to 365 daily points, each derived from 1440 logger scans of 22 flows and temperatures.
These are reduced to an array of (boiler) Total Heat, (Average) Outside Temperature and the (Daily) Temperature Swing.
The 3D array is fitted with a surface, but this has been changed from flat to twisted, giving a better fit (higher value of R2).
Projecting this surface to a Temperature Swing of zero gives the House Heat Loss line.
After adding the Internal Gains (Metabolic + Electricity), the Gross Heat Loss Line has an X-intercept of 22.5 C.