As will all renewable energy projects we started out by making sure that as much as the captured energy as possible was retained and did not leak out of the building. Cavity walls have been filled and extra insulation has been put into the loft space. While there was already insulation between the ceiling of the first floor rooms and the loft, additional insulation has been added to the roof of the loft itself. This means that the loft, which is heated by some of the thermal energy from the passive solar energy collection system, acts as a thermal barrier between the habitable rooms and the outside world.
It also has to be remembered that the conservatory and the solar collection chimney cover almost 25% of the exterior walls of the building. On an overcast day, with the outside temperature at zero the temperature in the conservatory reaches 8˚C and the temperature at the top of the chimney 12˚C. Not only does this radically reduce the temperature gradient between the inside and the outside of the building but it also provides a heat trap between the main entrance to the building and the zero degrees of the outside world.
The build up of the heat in the loft, conservatory and solar chimney is in part due losses from the building. However during daylight hours, even when the weather is overcast, there are enough ultra-violet waves converted to infra-red to raise the temperature within the thermal barrier. This heat is prevented from escaping by the k-glass double glazed units. When the sun shines the temperature in the conservatory rises to above 20˚C and to above 40˚C at the top of the chimney.