Well into Winter now and the very short days are here. Paradoxically this is the best time for heating the house from sunshine. Walking on the slate with bare feet when it is -4 degrees outside and opening curtains to let the sunshine in is a great pleasure. With sun coming in to nearly 4 metres almost all the floor is warm now. Late afternoon in the sun is t-shirt weather inside while it is 12 or so degrees outside. This is good and happily the double glazing works very well for the sunny days.
I still think there is some further benefit to be gained from increasing insulation in the roof and walls. That looks feasible before the next summer. Add the increased sunlight from removing shadows cast by the existing pergola and it could add 4 kWh of heating and reduce 12 kWh of cooling (heat leakage) to the daily winter heat budget – when I complete these improvements.
With energy costs approaching 15c and 25c for gas and electricity (per kWh) respectively that amounts to over a dollar a day in gas saving. Effectively $150 a year which is significant but secondary to the sheer comfort and joy of being in a warm and sunny place. Compared with 5 years ago, when I needed to have heating of some sort all of June and July all through the day or be quite cold, the difference is remarkable. 21 degrees inside with no heating on compared to 18-19 with heating on – guilt free :).