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Adding Value with Green Roofs

Kirstin Weeks, Arup

Green Roof Professional, LEED AP, CEM

Sir Ove Arup founded his practice in 1946 based on a belief in ‘total architecture’ integration and interdependence, innovation and the social purpose of design.

We shape a better world.

Photo Credit Lisa Lee Benjamin

Image: safeguardchem.co.za

Image Credit: Kay Cheng, SF Planning

Photo Credit Lisa Lee Benjamin

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Photo: Curran House Roof, Credit Brian Rose

Photo Credit Laura Tam, SPUR

Benefits and Uses of Green Roofs

Building Energy Savings,

Improved PV Production Acoustic Insulation

Stormwater Management Habitat and Biodiversity

Aesthetics and Quality of Life Job Generation

Roof Longevity

Urban Agriculture

Urban Heat Island Reduction

Air Quality Improvement

Accessible Open Space Property Value Increase

$

Stormwater Performance

• Retains 30% - 100% over the duration of a storm (up to 3.5”)

• Reduces runoff rate by up to 85% (avg 65%) • Deeper soil, low slope, retention features and

large roofs improve performance.

Heat Island & Energy

• Annual energy savings ~$0.17 per square foot of roof (varies widely by climate and building characteristics)

• Community wide energy and peak load reduction

Biodiversity and Habitat

• Governments developing ways to value natural ecosystems, i.e., Australia’s BushBroker scheme ($0.42 - $1.46/sf)

Photo Credit Laura Tam, SPUR

Quality of Life and Real Estate

• A study showed that access to views of greenery has increased productivity 2.9%

• Potential real estate value of ~$13 per square foot national (rents, expenses, vacancy, discount rates, absorption and lease lengths)

• Green roofs increase premiums of a building (i.e., green buildings) - ~2.5% nationally

age: IRS Kansas City, GSA

Photo: Denver EPA, Credit EPA

Photo: olpos.com

Photo: olpos.com

Green roof costs

• Maintenance costs: $0.04 to $0.30/sf/yr

3” extensive

6” semi-intensive

• Installation costs ($ per square foot): $20

$18 $16 $14 $12 $10

5,000 10,000 50,000

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($20)

($10)

$0

$10

$20

$30

Installation, Replacement & Maintenance

Stormwater Energy CO2e (Emissions, Sequestration &

Absorption)

Initial Real Estate Effect (Value, Rent

Absorption & Vacancy)

Community Benefits (Biodiv, Air

Quality, Heat Island, etc.)

Net

Pre

sent

Val

ue ($

/ft2 )

GSA Study Results – 30 yr NPV

-$17.5

$14

$7

$3

$13

$30

NPV = $2.70/ft2 IRR = 5.2% Payback = 6.2 years (Simple 15 yrs)

cost of green roof – cost of alternative = true green roof premium

Stormwater Management

Ordinance

83-10 May 2010

stormwaterdesignguidelines SAN FRANCISCO

Image Credit: SFPUC

True green roof cost = max $6/sf, min $0/sf

$3/sf!

min

Looking ahead…

www.spur.org\greenroofs

Roadmap for Green Roof Policy in SF

Image Credit: Kay Cheng, SF Planning

Image: 201 Folsom, Spinnakersf.com Image: Transbay Terminal

Image: Foundry Square IV

Kirstin Weeks, Arup 560 Mission Street, Seventh Floor San Francisco, CA 94105 direct 415 946 0746 mobile 415 730 6444 kirstin.weeks@arup.com GSA Report Link: http://www.gsa.gov/portal/category/104999

SPUR Roadmap for SF: www.spur.org\greenroofs

Contact Info and Links