[Greenbuilding] epdm vs. tar g(r)een roof
RT
Archilogic at yahoo.ca
Mon Aug 29 14:11:22 CDT 2011
On Mon, 29 Aug 2011 11:31:37 -0400, John Straube <jfstraube at gmail.com>
wrote:
> Speaking of cooking the books, Dr Lui's report, like most you will find,
> over sell the performance benefits of green roofs. They do this by
> comparing an excellent green roof design with the dumbest low slope roof
> we know how to build (an exposed membrane black roof).
I don't know if this is a fair criticism.
The first study that Dr. Lui did used a conventional roof that was
available on the NRC campus, and she simply installed a rudimentary Green
Roof over one half of the roof and then monitored what the two did over
the course of a year or so.
I think that was a fair comparison that highlighted the benefits of a
Green Roof over a "conventional" one because the "conventional" is a
fairly common type throughout North America.
At the time, I suggested to Karen that to be fair, her next study might
involve an IRMA (for comparison of thermal benefits) or a PMR and she
agreed, while at the same time wincing and rubbing the fingers and thumb
of an up-turned hand together indicating that acquiring funding was the
biggest problem. I don't know if Karen ever got the funding to do further
studies.
A PMR would of course provide similar protection for the membrane and
perhaps a similar reduction in the cooling load (my guess is most likely
"less" due to minimal contribution via evaporative cooling) but then the
Green Roof goes further and provides additional benefits which in an urban
core setting, extend beyond financial.
Do Green Roofs make much sense in a climate like Canada's where greenery
is either dead or dormant for a third or a quarter of the year ? Nyeh.
--
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c at Y a h o o dot c a >
(manually winnow the chaff from my edress if you hit "reply")
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