The Greening of the Rooftop Module 6 Green Roofing: Cool & Vegetated Roofs

1. The Greening of the Rooftop Module 6 Green Roofing: Cool & Vegetated Roofs

2. Green Roofing Systems Cool Roofs

3. Cool Roofs Cool Roofs and Urban Heat Islands Temperature Map of Atlanta 1972 v. 1993 Source: CNN.Com Temperature Profile of a Typical Urban City Source: LBL Heat Island Group

4. Cool Roofs Cool Roofs and Energy Savings Potential net annual energy savings from changing roof reflectivity (1) (1) LBL Heat Island Group. Savings are measured in dollars. Note that net savings equal the savings of cooling energy use less the penalties of heating energy use.

5. Cool Roofs Cool Roof Options • Cool Reflective Roofs • Cool Ballasted Roofs • Cool Vegetated Roofs

6. Cool Roofs Cool Reflective Roofs Cool Membrane Roofs Cool Metal Roofs Ice Mountain, Brea, CA Lindberg Terminal, St. Louis , MO

7. Cool Reflective Roofs Why Reflective Roofs? • Reduced cooling costs • Reduced peak electric consumption • Reduced Urban Heat Island Effect • Minimal cost penalty compared to alternatives • Field studies suggest long-term benefit with minimal maintenance* * But at a reduction in actual reflectivity.

8. Cool Reflective Roofs Reflectivity Standards Reflectivity Standards: Low-Slope Commercial Roofing Products Minimum Initial Reflectance 65% 70% n/a Minimum Aged Reflectance 50% n/a 50% Minimum Initial Emittance (2) n/a 0.75 n/a Certification Method Self-Report CRRC (3) CRRC (3) Reference Standard Energy Star (EPA) California Title 24 Product Standard California Title 24 Long-Term Value (1) • For energy calculation purposes • Emittance refers to the ability of a material to emit absorbed heat back into the atmosphere • Cool Roof Rating Council Product Rating Program

9. Cool Reflective Roofs Long-Term Reflective Performance Actual Reflectivity Values from Field Weathering Studies (1) Initial Reflectance: 75% - 90% 55% - 75% 15% - 55% 83% Aged Reflectance: 54% - 61% 40% - 57% 33% - 54% 59% - 76% Years Aged: 5 5 5 4 Product: Acrylic Coatings Aluminum Coatings Emulsions TPO Membranes (1) MRCA 5-Year Weathering Study for Coatings, WSRCA 4-Year Weathering Study for TPO

10. Cool Reflective RoofsBenefits & Limitations Current Limitations: Benefits: • Economical, especially for integrated reflective membranes • Effective: Demonstrated energy savings in warm climates, even after aging • Some current reflective membranes have a shorter performance history compared to other roof membranes • Cleaning and maintenance may be expensive & difficult • Reflective surface may cause glare into windows and increase interior heat loads • Reflective surface may raise winter heating costs in colder climates

11. Cool Reflective Roofs Geographic Comparison Example: 100,000 Square Foot Warehouse Heated & Air Conditioned Black Roof (5% Long-Term Reflectivity) Reflective Roof (55% Long-Term Reflectivity) R-10 / R-20 / R-30 Insulation Portland, OR Phoenix, AZ Los Angeles, CA Chicago, IL Atlanta, GA

12. Cool Reflective Roofs Geographic Comparison Heating & Cooling Comparison: Reflective Roof versus Black Roof(1) Heating Degree Days: 1154 1291 3090 6450 4461 City: Phoenix, AZ Los Angeles, CA Atlanta, GA Chicago, IL Portland, OR Cooling Degree Days: 3815 470 1611 749 279 Solar Load: (BTU/ SF/ Day) 1839 1579 1478 1243 1127 Annual Savings for Reflective Roof: R-10 R-20 R-30 $10,100 $3,300 $3,800 -0- -($1,000) $4,500 $1,500 $1,700 -0- -($500) $3,500 $1,100 $1,300 -0- -($400) • Comparison of 55% Reflective “Cool” Roof versus 5% Reflectivity Black Roof using DOE “Cool Roof Calculator” (http://www.ornl.gov/sci/roofs+walls/facts/CoolCalcEnergy.htm). Calculations based on a heated and air-conditioned 100,000 square foot single-story warehouse. Energy costs derived from 2007 EIA commercial $/KWH electricity costs by state for cooling (Arizona: $0.0824, California: $0.1282, Georgia: $0.0763, Chicago: $0.0707, Oregon: $0653) and estimated 2008-09 winter natural gas costs for heating ($1.20 per Therm). See also “The Economics of Cool Roofing: A Local and Regional Approach.” (J.L. Hoff, 2005).

13. Reflectivity and R-Value Balancing Energy Efficiency Annual Heating / Cooling Cost Savings: Reflective Roof versus Black Roof (1) (Dollars per 100,000 Sq. Ft. Roof Area / R-20 Insulation / Min. 55% Roof Reflectivity) (-$500) $0 $1000 $0 $1000 $1500 $1500 $2500 $2500 $3500 $3500 • Comparison of 55% Reflective “Cool” Roof versus 5% Reflectivity Black Roof using DOE “Cool Roof Calculator” (http://www.ornl.gov/sci/roofs+walls/facts/CoolCalcEnergy.htm). Calculations based on a heated and air-conditioned 100,000 square foot single-story warehouse. Energy costs derived from 2007 EIA commercial $/KWH electricity costs by state for cooling (Arizona: $0.0824, California: $0.1282, Georgia: $0.0763, Chicago: $0.0707, Oregon: $0653) and estimated 2008-09 winter natural gas costs for heating ($1.20 per Therm). See also “The Economics of Cool Roofing: A Local and Regional Approach.” (J.L. Hoff, 2005).

14. Cool Roofs Cool Ballasted Roofs

15. Cool Ballasted Roofs Tested at Oak Ridge Labs Envelop Systems Research Apparatus Oak Ridge National Laboratories

16. Cool Ballasted Roofs Cool Energy Savings Ballasted roofs may provide the same peak energy savings and reduced air temperatures as “cool” roofs … and their performance doesn’t degrade over time! Black Roof Standard Ballast White Roof Heavy Ballast Concrete Pavers Comparative Surface Temperature & Heat Transfer Source: Oak Ridge National Laboratories Envelope Systems Research Apparatus

17. Cool Ballasted Roofs Growing Recognition Ballasted Roofs with heavy ballast (25 lb/ft2)are now recognized as “Cool Roofs” in the 2008 version of California Title 24: “Roof constructions that have thermal mass over the roof membrane with a weight of at least 25 lb/ft² are exempt from the minimum requirements for solar reflectance and thermal emittance” (1) (1) Title 24, Part 6, of the California Code of Regulations: Energy Efficiency Standards for Residential and Nonresidential Buildings

18. Cool Ballasted RoofsBenefits & Limitations Current Limitations: Benefits: • Reduced cooling costs with minimal heating cost penalty • Economical installed cost on buildings designed to accommodate ballast loads • Established roofing system with a long performance history • Minimal loss of savings over time due to aging • Building must be designed to accommodate additional ballast weight • May not be suitable for high-wind regions • May not be suitable for roofs with high levels of roof traffic • May be difficult to find leaks and make repairs

19. Cool Roofs Find Out More … • EPA Energy Star Reflective Roofing • DOE Cool Roof Calculator (Oak Ridge National Laboratory) • Cool Roof Rating Council • EPA Urban Heat Island Project http://www.energystar.gov http://www.ornl.gov/sci/roofs+walls/ http://www.coolroofs.org http://www.epa.gov/heatisland/index.html

20. Green Roof Systems Vegetated Roofs Chicago City Hall Chicago, IL US Environmental Protection Agency Denver, CO

21. Green Roofing Options Why Vegetated Roofs? • Reduced heating & cooling costs • Reduced peak electric consumption • Reduced ambient air temperature • Reduced storm water runoff / improved storm water quality

22. Storm Water Runoff Storm Water and Combined Sewer Overflows Source: Clean Solutions for Omaha (http://projects.ch2m.com/Omaha_CSO/Faq.htm)

23. Storm Water Runoff Combined Sewer Overflows Combined sewer system are remnants of the country's early infrastructure and so are typically found in older communities. Combined sewer systems serve roughly 772 communities containing about 40 million people. Cities with Combined Sewer Systems Source: US EPA

24. Vegetated Roofs Reduce Storm Water Runoff Both Cumulative… And Peak… Source: Penn State University Cool Roofing Program

25. Vegetated Roofs Improve Storm Water Runoff Source: Penn State University Cool Roofing Program

26. Vegetated Roofs: Intensive Green Roofs Heavy Weight Very Heavy Weight Shrubs & Trees Soil Plants & Shrubs Soil 12” – 36” 36”+ Root Barrier / Drainage Mat Insulation Roofing / Waterproofing Membrane

27. Vegetated Roofs: Extensive Green Roofs Lightweight Moderate Weight Flowering Plants Soil Sedum Media 2” – 4” 4” – 6” Root Barrier / Drainage Mat Insulation Roofing / Waterproofing Membrane

28. Extensive Green Roofs May Require Minimal Maintenance May28, 2002 July 15, 2002 August 25, 2002 Typical Plant Growth in Central Pennsylvania Selected Sedum over Engineered Growing Medium Note: Growing Season Included a 30-Day Record Drought! Source: Penn State University Cool Roofing Program

29. Extensive Green Roofs: Modular Systems Sources: GreenGrid Systems (Top), LiveRoof (Bottom)

30. Vegetated Roofs Benefits & Limitations Benefits: Current Limitations: • Ambient air temperature reduced • Storm water runoff mitigated • Wide variety of hardy plants available • Require as little as 2 to 4 inches of planting medium • Can be combined with “cool” ballasted roofs to minimize initial costs • Tray systems available to reduce maintenance requirements • Underlying roofing / waterproofing system must accommodate increased maintenance traffic • Underlying roofing /waterproofing system may be required to resist root penetration • Leak detection may be difficult • Fire / wind resistance is uncertain • Roofing / waterproofing repair and maintenance may be difficult • Even hardy plants may require maintenance for ascetic reasons

31. Vegetated Roofs Find Out More… • Penn State Center for Green Roof Research • Green Roofs for Healthy Cities • NRCA Green Roof Systems Manual http://hortweb.cas.psu.edu/research/greenroofcenter http://www.greenroofs.org http://www.nrca.net

32. Cool Roofs / Vegetated Roofs Hybrid Systems

33. Hybrid Systems Strategic Combinations of Green Technologies • High Performance Insulation • Energy Efficiency • Drainage Control (Tapered System) • Cool Surfaces • Highly Reflective • Cool Ballast • Vegetated • Storm Water Retention • Ballasted Areas to Direct and Hold Water • Vegetated Areas to Hold and Consume Water

34. Hybrid Green Systems Hybrid Systems Schematic Highly Reflective Wall Flashings & Cool Ballast Lower Summer Temperatures Cool Ballast & Vegetation Retain Storm Water High Performance Insulation System Reduces Total Energy Costs Tapered Insulation Design Directs Storm Water

35. Cool Roofs & Vegetated Roofs Cool / Vegetated Roof Summary • Cool Roofs • Cool Reflective Roofs • Cool Ballasted Roofs • Vegetated Roofs • Intensive Systems • Extensive Systems / Modular Systems • Hybrid Systems