Saturday, June 16, 2007

Context: Green Roofs

Green Roofs for Healthy Australian Cities has a word press blog called Green Roofs. It’s a great source of posts and particularly photos.

A post from the start of May interested me. The Brisbane City Council (BCC) is looking at green roofs in the ‘Action Plan’ that is currently being drawn up by its Climate Change and Energy Taskforce.

For me, it’s an issue of context. Over most of the BCC’s area, green roofs would not be a good course of action.

Where are green roofs a good course of action? I think three factors need to be considered. These are:
1/ Rainfall
2/ Open space
3/ Insulation

Is local rainfall high enough that the addition high quality run off from a hard roof would not be missed?

Is the value of the additional usable open green space is greater value than the value of the addition high quality run off?

Is the value of the insulation provided by the green roof is greater value than the value of the addition high quality run off?

Background: Brisbane is a city currently in a water crisis, due to climate change and a lack of government planning (since an incoming state government cancelled a major dam in the late 1980s).

Over suburban Brisbane, the additional run off would be of great use for both as drinking and garden water.

Only in the inner city, would the value of a green roof as open green space and insulation combine to make is a good choice of action.


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