Therms vs. heating Degree Days, 65F Base

click legend labels to toggle data sets on or off

This is a scatterplot of therms used vs. heating degree days for several heating seasons, with linear regression lines added.

A smaller slope should indicate greater efficiency.

For more information about this kind of benchmarking and potential pitfalls, see Degree Days - Handle with Care! from

Upgrades / changes:

  • 2001 - Bought house, installed 82 AFUE boiler
  • Feb 2005 - New double-pane windows
  • Nov 2006 - Attic insulation and sealing
  • Feb 2010 - Wall insulation retrofit, more attic work
  • Mar 2011 - New heating zone in basement
  • Oct 2013 - New renovation; 600 ft^2 added, new insulation, 1 new zone
  • Nov 2014 - New 95 AFUE mod/con boiler with outdoor reset and indirect DHW
You can read more about this on my blog.