Everything we do has a consequence is something I always think...
14c compared to some peoples house temps is very low, yet our house is quite well insulated and the heating system very efficient for a gas boiler
But because we have that tolerance to the cold, the house is never as warm as some peoples, add the fact the heating will go off at maybe 6pm, driven by the fact we can't stand an overly warm house to sleep in....consequence, the heat you put in the house during the day, almost every day...is lost.
Ironically jts always occurred to me a heat source system, pumping out a steadier and perhaps lower temperature might be better for us. But the initial installation cost, uncertainty of outcome, lack of solar panels, further cost to beef up insulation and solar simply don't make economical sense atm.