Just after general feedback about a local Australian issue.

My question is, in what situation would you advise thermal bridging though the building envelope to improve the energy efficiency of a building?

Our National energy simulation software for houses gives a result in stars. The minimum result for building permit compliance must be 6 stars, and the rating can go as high as 10 stars.

The software is mainly driven by ‘passive solar’ principles.

The issue that I have with the software is that it rewards conductive heat flow, (thermal bridging) through the building envelope. i.e. dark roof, dark walls, and dark aluminium window frames are promoted to improve the ‘performance’ (Star rating) of the house. A dark colored, thermally bridged house with no eaves can be considered to be more energy efficient that a light colored, thermally broken, well shaded house.

For a bit of context, the climate where I live is close to that of San Francisco/Oakland, but with hotter summer temperatures.

All comments are welcome. This has been driving me nuts for years.

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Replies

  • Umm never... We don't like thermal bridges & rather keep conditioned air in

    As an FYI & I might start a war with this but the "color" doesn't matter too much - reflectivity of a material does

    • Thanks Sean,
      Yes, the color is just a general indicator. The software attributes an absorptance value to color. I generally advise that cladding is battened, providing a shading, ventilation and drainage plane.
      I've been arguing against thermal bridging for 14 years now. Not surprisingly our new houses are getting very hot in summer.

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