Tuesday, April 12, 2011

Mid April update

12 April '11 : I have been in New York for a week, so hot water use has been reduced a bit, and the week has also been very sunny for this side of April. Mrs N-C has been here, so the house still needed evening heating and lighting. The Sunboxes work by themselves of course, even if the GSHP is not running. So we have broken three records in the last week :
• The annual House consumption really has dipped below 5,500 kWh.
• The annual GSHP consumption (incl. the circulating floor pump) really has dipped below 3,500 kWh.
• The annual Sunbox capture has risen above 3,000 kWh. (although I had been mentioning a round figure of 3,000 for many months, the precise figure was 2,980 until this week of April).

Plus a few more things:
• The deep ground temperature is rising slowly, and was 11.6 ºC compared with 9.2 ºC exactly a year ago (a month after the Sunboxes first installed). That is equivalent to a stored reserve of about 4,000 kWh of heat more than in the year before - and it is only April, with months of summer to come.
• The average daily heat pump consumption from Jan 1 to April 11 2011 was 14.04 kWh whereas in the same timeslot of 2010 it was 21.21 kWh. This is a 33% improvement, helped by the very mild spring we have experienced, and the cold spring of 2010.
• The average daily House consumption from Jan 1 to April 11 2011 was 19.65 kWh whereas in the same timeslot of 2010 it was 27.85 kWh. This is a big improvement, as explained above.
• Looking at the Weather effect, the ratio of Degree Days for Jan 1 to April 1 2011 was 896, and it was 1100 in 2010. This means that the ratio was 18%, whereas the performance improvement in the GSHP was 33%.

Next Step? Well, logically, it has to be to dip the House and the GSHP another 100 kWh lower, to 5,400 and 3,400 respectively. I will be amazed if this is possible, but an average of one kWh per day less during the summer season will achieve it. If the autumn is mild it will be achieved.

17 April '11 Postscript: Well the week since the 12th has not been so sunny, so the PV and SB count is slightly lower. But I am glad to see that the electric consumption figures for the House and the GSHP have fallen further - the record is extended. The deep ground temperature has risen above 12ºC at last.
   One year ago in the same time period was a cold week so  it's possible that the readings for Sun. 24 April will be even lower! Next stop, 5,450 and 3,450 !

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