The ground source heatpump was of more academic interest because it's so difficult for most people to fit unless they are building new. Quite a few of the visitors were eco-renovating their houses in some way, one of whom seems definitely interested in a GSHP, and perhaps if I my experiment this coming summer and winter prove it will make it more efficient, a Sunbox addition. Actually, for a larger house, or a Victorian house with more heatloss, I feel that it is more strongly justified, providing you can find somewhere to put it, as the heatpump on its own is going to have a tough workload.
I made a Powerpoint before the visitors arrived, and although this only got one showing, it is useful to have one now for future lectures on the topic of the GSHP and Sunboxes. I will try to make it available to readers here as a PDF on line.
Tina Holt and Tim Saunders. joint organisers of the event joined the visitors. Let's hope the whole Transition adventure continues.