That sounds pretty good to me too. The reason I ask the question is that a lot of the discussion about insulation is about R and u-values, thermal conductivity, insulation materials and thicknesses. All important and necessary. But what does it mean in practice? I have 300mm fibreglass in my ceiling (its a single storey extension), and Warmfill Silver Bead in the cavities (as well as the original aeroboard). I can calculate the u-values. But the question remains: is a fall of five degrees overnight (from 20 to 15) reasonable/acceptable in modern insulation conditions? What should consumers expect in practice?