The Conservatory as a Heating Appliance - 30th January 2010

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 theEnergyCrowd’s 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 tube in the loft space. Cold air from the house is vented into the conservatory.

In late December the sun started to warm the conservatory at 10am and continued to do so until it set at approximately 4pm. With the outside air temperature at – 1.3 degrees the inside temperature reached at 13.9 degrees. Later in the day with the outside temperature at 3 degrees the temperature inside the conservatory reached 22.7 degrees. A thermostat ensured that air was not drawn out of chimney until the air midway up in solar chimney reached 35 degrees, at which point the air in the top of the chimney, from where the air was drawn, had reached in excess of 45 degrees C. The thermostat cut out when the air temperature midway up the chimney fell to 25 degrees and the air in the top of the chimney was still 35 degrees C.

The insulated ducting took approximately 5 minutes to warm up and the air entered the house at 27 degrees C on a typical sunny winter day. The solar energy falling on the conservatory and the solar chimney was 350 watts/m². However on days when there was 800 watts/m² of solar energy landing on the conservatory and chimney the air entered the house at up to 37 degrees C. – see results below.