Space Heating

Space Heating | Low Temperature Solar Thermal in Australia | Further Information | References

Low temperature solar thermal technologies, especially those that do not generate electricity, rely on the scientific principles behind the Greenhouse Effect to generate heat. Electromagnetic radiation from the sun, including visible and infrared wavelengths, penetrates into the collector that is absorbed by the surfaces inside the collector. Once the radiation is absorbed by the surfaces within the collector, the temperature rises.

Space Heating

Space heating operates in the same way as for solar cooking - using the greenhouse properties of certain building materials, particularly glass to trap re-radiated heat from the sun within the confines of the conservatory, or sunspace.

Conservatories (Sunspaces)

A conservatory, or sunspace is a greenhouse that is integrated into the building structure, like a glass-enclosed room (see Figure 1). This room, a habitable solar collector, is common in cooler temperate climates as found in southern and eastern Australia and New Zealand. Heat is generated in the conservatory, using incoming solar radiation, which preheats the air before it circulates into the main building. Heat energy is stored within the thermal mass of the building, especially the wall between the conservatory and the remainder of the house.

Figure 1 A schematic of a conservatory
(Adapted from Boyle, 1998)

Trombe Wall

Building on the concept of a conservatory for space heating, the Trombe Wall was developed by Felix Trombe in the 1950s and was first used in the south of France. In this space heating system, the conservatory is replaced by a thin air space behind a storage wall (used for storing heat energy). Incoming solar radiation is absorbed and stored as heat in the thermal mass contained within the storage wall. Heat is transferred into the building by radiating the heat directly into the building (see Figure 2).

Figure 2 A schematic of a Trombe Wall
(Adapted from Boyle, 1998)

As an additional feature, ventilation windows between the Trombe wall and the building can be opened to allow circulation of the preheated air, thus increasing the heating performance of the Trombe Wall. At night, or on cold days, these small windows can be closed to prevent the loss of heat energy from the building. In practice, a Trombe Wall can exist in many forms, particularly in retrofit situations, where modifications are being made to the building after construction has been completed. Examples of retrofitted walls could include small-scale collector panels or boxes fitted to the roof or wall, flat plate collectors, or the covering of the sun-facing (north) wall with transparent insulation.

Direct Gain

The most common and easiest method of solar thermal space heating is the direct gain of heat energy through north facing windows and glass doors (see Figure 3). Incoming solar radiation is transmitted through the transparent glazing and is absorbed by objects, including walls and floor, inside the building. Direct gain is the same principle that results in a warm car interior on a cold, but sunny day.

Figure 3 Direct gain
(Adapted from Boyle, 1998).

Low Temperature Solar Thermal Technologies in Australia

For some of the research in solar thermal technologies in Australia click here

Further Information

RISE Resources - Information regarding available renewable energy resources.

RISE Technologies - An extensive collection of information regarding renewable energy technologies.

RISE Applications & System Design - Renewable energy application information and system designs.

RISE System Displays - Case studies and information on installed renewable energy systems & performance data.

The Energy Resources Institute – Solar Thermal

The Solarserver – Solar Thermal Technologies in the United States

Australian National University – Solar Thermal Energy Research

Wikipedia – Solar Energy

Renewable Energy Commercialisation in Australia – Solar Thermal

References

None.