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Evaluating Green Roof Energy Performance. Sonne, J. 2006. The
American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE)
Journal. 48(2):59-61. (Journal article)
We know that green roofs contribute much less to overflow
storm water drainage than do conventional roofs, but how much? Sonne’s study,
comparing green roofs to conventional roofs, indicates it could be a good deal.
The average maximum green roof temperature in the study proved to be 39°F cooler
than the conventional roof. The green roof reduced heat flow through the roof by
70-90%, which in turn reduces cooling costs.
Some figures and tables you might be interested in checking
out:
- Fig. 1: Roof diagram with sensor locations
- Fig. 2: Building section diagram
- Fig. 3: Comparison of average roof surface temperatures
- Fig. 4: Comparison of average roof heat fluxes
This publication is specific to building codes in Portland,
Oregon, but can be useful to anyone living in our region. Information ranges
from the benefits of ecoroofs to installation in the home. Benefits include
reducing runoff, lowering temperature of runoff (which may lead to cooler stream
temperatures), increasing vegetation and wildlife habitat, and creating a market
for recycled materials such as mulch and compost. Using simple language and
descriptive diagrams, the text outlines where ecoroofs can be used and what they
cost and look like. Although the immediate cost is more expensive than a
conventional roof, it is important to remember that ecoroofs last about four
times as long. The article explains important ecoroof criteria, plants to use,
and other details such as access and leakage. It also provides a list of
contacts with experience in the design and construction of ecoroofs.
Green Roofs from Green Roof Blocks. Green Roof Blocks
Homepage.
www.greenroofblocks.com
Ever think that retrofitting your home with a green roof would
be daunting or completely out of the question? “The Green Roof Blocks” website
introduces visitors to the concept of pre-fabricated green-roof materials
something that can make the job much less overwhelming. Green Roof Blocks offers
the following features:
- 2 x 2 ft blocks that easily rest on a rooftop
- Includes live plants and growth media
- Simply set them in place and your green roof is complete
- Ready for shipping anywhere in the U.S. or Canada
- Priced from $15/sq. ft.
Apparently, most roofs require no additional support to
accommodate Green Roof Blocks. Obviously, a qualified contractor is the one to
advise you on your particular situation. Green Roof Blocks claims to reduce
storm water runoff, improve air quality, and ease the urban heat island effect.
Valuable to know!
Green Roofs, Extending Our Environment and Our Industry.
Barrett, T. February 2006. The Michigan Landscape. 49(2):23-27.
(Magazine article)
With over two million square feet of green roofs, Chicago is
providing stiff competition with Portland for being one of the “greenest” cities
in the country and behind these two cities is the state of Michigan with its
green roofs. This is a great little article that defines green roofs, has some
photos including a doghouse with a green roof, and it includes a source page for
materials and research.
Published by the City of Portland, this brochure explains that
an ecoroof, or green roof, is a lightweight, low maintenance vegetative roof
that is used in place of a conventional roof. Green roofs are passive measures
of energy conservation because they provide, among other environmental benefits,
insulation and lower cooling and heating costs for a home or other buildings.
The cost of an ecoroof can be 2-3 times more than a conventional roof. However,
green roofs save money in the long run by lasting longer and reducing the
rapidly rising heating and cooling expenses.
Components of a green roof are illustrated in a diagram with
easy to read explanations. This article also explains operating steps,
maintenance, and a plan for replacement of a green roof with lots of great
graphics. Visit this site for a few local examples (Portland, Oregon) of green
roofs that you can see up close and personal. Resources are provided for local
assistance with your ecoroof project, as well as a list of vendors and
manufacturers of ecoroof products. Use this informative site as the first step
in growing your own green roof!
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