This document discusses the benefits of green roofs and provides information about their costs and performance. It summarizes that green roofs can provide stormwater management benefits like retaining 30-100% of rainfall, reduce energy costs for buildings by around $0.17 per square foot annually, and provide habitat. Installation costs range from $10-20 per square foot depending on the type of green roof. A case study found that over 30 years, a green roof can have a positive net present value of $2.70 per square foot and payback period of 6.2 years. The document advocates for policies to promote green roofs in San Francisco.

1. Adding Value with Green Roofs
Kirstin Weeks, Arup
Green Roof Professional, LEED AP, CEM
1

2. 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.

3. Image: safeguardchem.co.za
Photo Credit Lisa Lee Benjamin

4. Image Credit: Kay Cheng, SF Planning

5. Photo Credit Lisa Lee Benjamin

6. 6

7. Photo: Curran House Roof, Credit Brian Rose
7

8. Photo Credit Laura Tam, SPUR

9. Benefits and Uses of Green Roofs
Stormwater Management
Roof Longevity
Habitat and Biodiversity
Building Energy Savings,
Improved PV Production
Urban Agriculture
Acoustic Insulation
Air Quality Improvement
Aesthetics and Quality of Life
Job Generation
Urban Heat Island Reduction
Accessible Open Space
Property Value Increase
$

11. 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.

12. 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

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

15. Photo Credit Laura Tam, SPUR

16. 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

17. age: IRS Kansas City, GSA

18. Photo: Denver EPA, Credit EPA

19. Photo: olpos.com

20. Photo: olpos.com

21. Green roof costs
• Installation costs ($ per square foot):
$20
6” semi-intensive
$18
$16
$14
$12
$10
3” extensive
5,000
10,000
• Maintenance costs: $0.04 to $0.30/sf/yr
50,000

22. GSA Study Results – 30 yr NPV
NPV = $2.70/ft2
Payback = 6.2 years
(Simple 15 yrs)
IRR = 5.2%
$30
$30
Net Present Value ($/ft2)
$20
$14
$13
$7
$10
$3
$0
($10)
-$17.5
($20)
Installation,
Replacement &
Maintenance
22
Stormwater
Energy
CO2e (Emissions,
Sequestration &
Absorption)
Initial Real Estate
Community
Effect (Value, Rent Benefits (Biodiv, Air
Absorption &
Quality, Heat
Vacancy)
Island, etc.)

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

24. stormwaterdesignguidelines
SAN FRANCISCO
Stormwater
Management
Ordinance
83-10 May 2010
Image Credit: SFPUC

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

26. min
$3/sf!

27. Looking ahead…

28. Roadmap for Green Roof Policy in SF
Image Credit: Kay Cheng, SF Planning
www.spur.orggreenroofs

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

31. Contact Info and Links
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.orggreenroofs