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GSBN:Re: Living Roofs

Hi John - I have no hard data - and it is a very dynamic situation and
surely difficult to model.

I assume you are asking in terms of the internal environment under the roof.

I have seen "made-up" calcs that consider living roofs and their plants as
insulating blankets, -  which may work when dry.  But the real killer for
considering using living roofs as insulation is considering them when they
are saturated. Undoubtedly there are cooling effects from this, and thermal
mass effects but how to quantify them I don't know.
On a clear night roof surfaces are exposed to deep space at -273 degrees C,
so cooling effects are potentially large - and plants will moderate this.
On a cloudy/windy/rainy night,  or day.....?

Therefore, I always add insulation layers into a living roof to moderate
heat loss and gain.

If we consider the external environment, I saw a meteorologist Carol Skinner
in Melbourne, Australia, present some very interesting work on the effects
of living roofs as very worthwhile moderators of the thermal and stormwater
environments in cities.  Her work is not published yet as far as I know, and
I'm still trying to obtain her data myself.

A living roof also helps compensate for the area of biota removed by a
building's footprint.  And potentially might provide some food, for bees if
not humans.

Graeme North Architects,
49 Matthew Road,
RD1, Warkworth,
New Zealand 1241
Ph/fax +64 (0)9  4259305


> From: "GSBN" GSBN@...
> Reply-To: "GSBN" GSBN@...
> Date: Fri, 17 Mar 2006 23:22:03 -0600
> To: "GSBN" GSBN@...
> Subject: GSBN: Digest for 3/17/06
> Hi,
>> Does anyone know of some hard data on the thermal qualities of living
>> roofs.
>> I've done some preliminary energy modeling, in Energy 10, and come out
>> with
>> very little difference.  I presume that's because the program can't
>> account
>> for the shading of plants, evaporative cooling effects of moist soil,
>> and
>> perhaps the ability of the earth to hold heat, then release it to the
>> night
>> sky.  Is there some real data on this?
>> John