Green Roofs - Living Architecture Monitor - Winter 2017 - 9

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66
NET PRESENT VALUE OVER 25 YEARS, PER SQUARE FOOT OF AN EXTENSIVE GREEN ROOF
ON AN EXAMPLE NEW OFFICE BUILDING IN DENVER BY BENEFIT CATEGORY.
Source: Making Informed Decision: A Cost-Benefit Analysis of Green Roofs in Denver

$25

$20

$15

$10

NPV ($/FT2)

$5

$0

($5)

($10)
($15)

($20)
($25)

INSTALLATION, STORMWATER
REPLACEMENT &
MAINTENANCE

ENERGY

CO2

(EMISSIONS,
SEQUESTRATION
& ABSORPTION)

program can eliminate the disincentive for developers to invest
upfront in green roofs when many of the benefits accrue to the
ultimate owners of the building in years to come.
The city-wide cost benefit analysis used conservative
assumptions including high costs of installation and low
applicability to existing building stock. The analysis showed
that after 15 years of I-300's implementation, Denver would
build an estimated 57.5 million square feet of green roofs, at a
total installation and maintenance cost of $1.34 billion (PV).
These roofs would generate a number of public and private
benefits, including 25,000 job-years of employment, $445
million in local food produced, $573 million in increased roof
lifespan, and $171 million in savings from a reduced urban
heat island effect (Denver has the third worst heat island in the
US). Looking into the future, as these roofs built in the first
15 years continue to accrue benefits but costs are limited to
LIVINGARCHITECTUREMONITOR.COM

BIOPHILIA

(MEASURED
PRODUCTIVITY
& ABSENTEEISM)

REAL ESTATE ENVIRONMENTAL COMMUNITY
EFFECT
BENEFITS
BENEFITS
(VALUE, RENT,
ABSORPTION
& VACANCY

(BIODIVERSITY, AIR
QUALITY, HEAT ISLAND)

maintenance, their Net Present Value is a staggering $1.85
billion.
The I-300 initiative was
passed by a majority of
Denver voters on November
7. This was undoubtedly
thanks to the determination
of the Denver Green Roof
Initiative volunteers, as well as
the engagement of Denver's
citizens. At the same time, this
cost-benefit report provided
a strong argument for implementing green roofs in Denver, and serves as a foundation

(ECONOMIC)

for future analysis. More work
needs to be done to fine tune
the requirements and provide
additional information about
the public and private benefits
of green roofs.
To read the full cost-benefit
report, visit www.livingarchitecturemonitor.com/Denver
Rohan Lilauwala is Program
Manager at the Green Infrastructure Foundation and Senior
Researcher at Green Roofs for
Healthy Cities. rlilauwala@
greenroofs.org

LIVING
LIVINGARCHITECTURE
ARCHITECTUREMONITOR
MONITOR/ /SUMMER
WINTER 2017 / 9
http://www.livingarchitecturemonitor.com/denver http://www.LIVINGARCHITECTUREMONITOR.COM
Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Winter 2017
