I did an experiment last night, gave the central heating a trial, including the underfloor heating downstairs. The temperature in my lounge was 23 degrees at 8pm when the heating went off. My wooden shutters were all closed by then and the 2 patio door blinds were down, honeycomb perfect fit. Three vents were open on the other side of the shutters. 3 windows in the lounge and 2 narrow patio doors
It felt lovely and cosy when I came down this morning, no extra heat was added after yesterday. The lounge temperature is still on 23 and the shutters are still closed. The insulating beauty of wood, I feel the difference. The shutters are not just loevly to look at