From: Jonathan Beers [j_beers@hotmail.com]
Sent: Tuesday, May 10, 2011 12:20 PM
To: Rhodes-Conway,Satya; Hoffman, Jeanne; dmosiman@madison.com
Subject: Green roofs requirement in Madison Sustainability Plan
Hi
Satya, Jeanne and Dean,
I
read Dean Moisman's article about Madison's Sustainability Plan, and
support most of the provisions. However, I'm skeptical about the green roof
requirement. I'd rather see performance requirements for energy consumption and
water runoff.
Have
you seen the writings of green roof skeptics? Here's an excerpt from
"Prioritizing Green - It's the Energy Stupid" by ASHRAE fellow Joe
Lstiburek. I'm an energy-efficiency professional, and Lsitburek is
well-regarded in the building science world (and is known for his provacative
style). Roofs have traditionally been a way to shed water. Green roofs hold
water, and are expensive to do right. (See Fig. 2-3 in the
article for illustrations.)
>>>
Dr.
Joe Lstiburek wrote:
"Green
roofs? Grass and dirt are not energy efficient.
Work
with me here. Which saves more energy—2
inches
of dirt or 2 inches of insulation? Which saves
more
energy—grass or a white colored membrane?
Which
is more expensive and does not save energy—
grass
and dirt or insulation and a white colored
membrane?
Which needs to be watered to keep the
grass
from dying and blowing away? But they are
beautiful
and look cool. And that apparently is more
important
than cost and energy savings. Okay, I can
live
with the beautiful and looking cool argument if
that
is in fact the argument—but don’t clutter it with
half-truths
such as heat island effects and water runoff.
There
are other ways to deal with each.
I
know I will not win the argument on green roofs, so
my
advice is to at least build the green roofs correctly."
<<<
I've toured the green roof at the EPA's Denver headquarters, and spoken with a
City of Chicago engineer about their green roofs. It's easy to do green roofs
wrong, and hard to do them right. I support plans that will achieve low energy
consumption and reduced runoff, rather than prescribing green roofs as the
solution to those problems.
Sincerely,
Jonathan Beers
534 Maywood St.
249-9976 home
j_beers@hotmail.com