Energy

Designing homes to conserve energy and use it efficiently, from sources that cause least environmental harm.

Solar water heating

Solar water heating is energy-efficient, has low running costs (typical water heating costs may reduce up to 75% in summer and 25–45% in winter) and has low greenhouse gas emissions. However, solar energy is variable, and systems will not be as effective on cloudy days, so a booster system is required to provide water heating in periods of high demand or low solar gain. Solar water heating systems can also feed into other water heating systems such as instant gas.

Key design decisions will include:

  • size, location and type of the collector panels
  • whether to use an open or closed loop heat transfer system
  • whether to use a pump or thermo-siphon for heat transfer
  • size and location of the cylinder.

An important factor in the efficiency of solar water heating systems is how systems are configured and how well they have been installed. It is generally more expensive to retrofit a solar water heating system in an existing house than to install a system in a new construction.

G12/AS2 provides an acceptable solution for the installation of solar water heaters provided that:

  • the system does not include a cylinder on the roof
  • the building is not too windy
  • the system has a collector that is no more than 4 m2 and is below weight restrictions
  • the system has a collector that is not attached at a angle below 45° to the ground.

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