Green Roofs - Living Architecture Monitor Winter 2020 - 10

live which increases the overall diversity. For those of you who are
interested in learning more about diversity on green roofs I highly
recommend reading the Susan Cook-Patton and Taryn Bauerle
paper 'Potential benefits of plant diversity on vegetated roofs: A
literature review' that was published in the Journal of Environmental Management 106 (2012) 85-92. Also, Jeremy Lundholm at St.
Mary's University in Nova Scotia has published numerous excellent
peer-reviewed papers on green roof plant diversity. Just google his
name in Google Scholar and you will find them.
Back to the original question, does diversity increase profits for
green roofs? I guess the answer could be yes or no. It depends on
the client. Deeper substrate depths (or more accurately a variation
in substrate depths) increases the number of potential plant species
that can be grown which in turn increases the number of animals
that may inhabit that roof. A more diverse natural looking roof may
be very important to some building owners and not so important
to others. As with landscapes at ground level, some prefer neat
tidy edged lawns and others like native prairies. Keep in mind that
a more diverse roof likely means a deeper roof with additional
weight and thus some added expense for installation materials and
the possibility that the roof may not be sold due to weight limitations.
We should also address the question of who is profiting from
the green roof? Are we talking about the building owner, the green
roof contractor, or the community at large? As discussed above,
vegetation choices and the accompanied substrate depth can influence energy consumption and stormwater runoff in a positive way.

LIVING ARCHITECTURE MONITOR / WINTER 2020 / 10

Therefore, a building owner
can save on their energy bill.
Depending on where the roof
is located and the policies
enacted by the local government, stormwater management
may be more of a community
benefit. It is a benefit to the
greater good, but the building
owner may not experience a
direct financial benefit in some
places. In addition, a company
operating from building with
a green roof can also use the
roof to their advantage from
a marketing angle. If you are
promoting yourself as a green
company then having a diverse
green roof that reduces stormwater runoff, saves energy,
and provides wildlife habitat
would back up what you are
saying. From the contractor's
perspective, all of these benefits can be promoted to help
make a sale. Other green roof
benefits are difficult to quantify

economically, especially for
the individual building owner.
Everyone has a different idea
of what is aesthetically pleasing
and bird watching is important
to some people and not to
others. It really comes down
to what the client wants, what
they are willing to pay to meet
their needs, and how the local
government values green roofs
as a tool to benefit the greater
good.
Brad Rowe has been conducting
green roof research at MSU since
2000. Research topics include
plant selection, growing substrates,
carbon sequestration, stormwater
runoff, energy conservation, and
roof vegetable production. He was
the founding co-chair of the GRHC
Research Committee and received
the GRHC Research Award of
Excellence in 2008. Brad also
teaches a course on green roofs and
walls at MSU.

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Green Roofs - Living Architecture Monitor Winter 2020

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