The ambient temperature of the house settles back to around 22.5c to 23.5c downstairs in the mornings (as it has done since Mid July). 25-26's in heatwaves that settle back after 5 days.
I've worked out that this ambient inside temperature is approximately 3 to 4c warmer than the outside average temperature (July and August were 19.7 and 20.4 respectively).
Sub 19c is fairly uncomfortable for sitting still indoors meaning that outside average temperatures will need to fall sub 15c for that urge to click some heating on. By my reckoning that will be early October.
Light breezes and sunny days will prolong the internal warmth.
Originally Posted by: Gusty