Key performance indicators:
1. GSHP effort related to degree days
2. Deep ground Temperatures
Meanwhile, above are two key performance indicator diagrams which I needed for my SET 2011 article.
Left: The comparison of Degree Days in Nottingham (Red, indicating the level of space heating required) and the workload of the GSHP for heating (Blue curve, in kWh/month) This indicates that the GSHP worked with less electrical consumption even though the winter was more severe in Nov-Dec 2010.
Right: The deep ground temperatures measured since August 2009. My measuring method now is very rigorous, with fewer ups and downs than in 2009. But the smoothed trend is very visible, with the ground temperature falling to 5º in Winter 2009-2010 and only falling to 10º in Winter 2010-2011.