Passive Solar Energy For Space Heating

One of the main problems associated with energy efficient double glazing units is the build up of heat in rooms where they are used – hence the thriving market for blinds tailored to fit conservatories. However in winter the idea of using a conservatory as a household-heating appliance is attractive. In this test installation, warm air from the conservatory rises through a glazed chimney and, in winter and autumn months, is drawn down into the house, via and insulated ducting running through the loft space. Cold air from the house is vented into the conservatory.

The construction of the passive solar collection system is as much a secondary glazing project as a renewable energy installation. As most secondary glazing installers also construct conservatories this solar energy capture system would provide an ideal added value product for installers who were diversifying by addressing the green energy market.

Air conditioning engineers already supply systems that manage the flow of air around buildings. Passive solar energy can add value to air conditioning systems and could also be used to upgrade existing installations.

This technology could also be used to reduce emissions from buildings which are currently not zero carbon.

The 'solar chimney' has been mounted on the southwest facing gable end of the house. This takes advantage of the afternoon sunlight and, the fact that it was mounted on the wall as opposed to the roof, means it has an angle of incidence with the winter sun as close to 90° as possible. Air warmed in the chimney is also drawn into the loft space.

The conservatory is a totally glazed structure incorporating 24mm (roof) and 28mm (walls) thick K glass DGUs.

In the early afternoon during mid-winter the maximum area of the combined chimney and outhouse exposed to sun at an angle of 90° is 16 square metres.