John, you are preaching to the converted... THREAD DRIFT WARNING.
I once lived in a house with 12" sealing height and remember climbing the step ladded to replace the light bulb.. and breaking out in a sweat given the variation in temps from armchair to lightbulb..!
As a self build extension project I have doubled the floor space of our house, and in the process had to commit to modern building regs re heating and insulation which added considerably to cost and effort which I grudged at the time. Though having typed that, I did install room zoned underfloor heating (JonG4) in all the rooms of the extension, one of which was s sun room.
Never thought of as any part of the design was that even mid Winter with snow on the ground, we would be too warm in the sun room, and thus open the doors to the adjoining rooms not only to cool the sun room down, but to circulate heat around the rest of the extension.. In time becoming aware of the effect of the insulation in the new extension in terms of average room temperatures, as part of a refurb of the existing house, I insulated all the external facing interior walls, upgraded to modern rads, boiler, double glazing and loft insulation. We and now can heat the place to a reasonable temperature in every room for a similar cost that which we paid in energy bills for the original and smaller house in past years....
Those folk from Insulate Britain may have the right idea, even if they upset folk considerably trying to get the point across..?
