Stormwater Academy: Green Roofs Green Roof Design and Operation Operation (Part IV) 2006 FSA Annual Conference June 14, 2006 By Marty Wanielista and Mike Hardin FSA

DESIGN and CONSTRUCTION LEED Certification Energy Performance Conclusions and Recommendations Questions and Comments

LEED (Leadership in Energy & Environmental Design) Green Building Rating System A leading-edge system for designing, constructing, operating and certifying green buildings.

LEED-NC Ratings Certified:26-32 Points Silver:33-38 Points Gold:39-51 Points Platinum:52-69 Points

LEED & Stormwater Management Sustainable Sites Prerequisite – Erosion and Sedimentation Control Credit 5.1 – Reduced Site Disturbance Credit 6.1 & 6.2 – Stormwater Management Credit 7.1 & Landscape & Exterior Design to Reduce Heat Islands

Sustainable Sites Credit 5.1 – Reduced Site Disturbance: 1 Point Intent: Conserve existing natural areas and restore damaged areas to provide habitat and promote biodiversity. Note: One point Credit 5.2 can be obtained as an indirect point if the project qualifies for the SSCredit 2.

Sustainable Sites Credit 6.1 & 6.2 – Stormwater Management: 2 Points (Rate & Quantity) Intent: Limit disruption of natural water flows by minimizing stormwater runoff, increasing on-site infiltration and reducing contaminations.

Sustainable Sites Credit 7.1 & Landscape & Exterior Design to Reduce Heat Islands 2 Points Requirement: Use ENERGY STAR compliant (highly reflective) AND high emissivity roofing (emissivity of at least 0.9 when tested in accordance with ASTM 408) for a minimum of 75% of the roof surface; OR, install a green (vegetated) roof for at least 50% of the roof area. Combinations of high albedo and vegetated roof can be used providing they collectively cover 75% of the rood area.

Water Efficiency Credit 1.1 & 1.2 – Water efficient landscaping reduce potable water usage 2 Points Intent: Limit or eliminate the use of potable water, or other natural surface or subsurface water resources available on or near the project site, for landscape irrigation.

Energy and Atmosphere Prerequisite 1 – Fundamental Commissioning of the Building Energy Systems Prerequisite 2 – Minimum Energy Performance Prerequisite 3 – Fundamental Refrigerant Management Credit 1 – Optimize Energy Performance Credit 4 – Ozone Depletion

Energy and Atmosphere Credit 1 – Optimize Energy Performance 3 Points Intent: Achieve increasing levels of energy performance above the baseline in the prerequisite standard to reduce environmental and economic impacts associated with excessive energy use. Note: There is a total possible of 10 points but the average green roof will only be able to obtain 3 points

Energy and Atmosphere Credit 4 – Ozone Depletion 1 Point Intent: Reduce ozone depletion and support early compliance with the Montreal Protocol while minimizing direct contributions to global warming.

Florida: Green Roofs Example Temperature Comparisons o F Source: and click on roof monitoring datawww.stormwater.ucf.edu Conventional Roof (red) versus Green Roof (green) at the roof surface In the evening, radiation is present and conditioned space losses to the roof.

Energy Performance Reference: Jeff Sonne, FSEC ASHRAE Journal Feb Sustainability section: Evaluating Green Roof Energy Performance.. There is 18.3% less heat loss with the green roof compared to the conventional roof and as the conventional roof ages (turns from a silver to black color), the difference will be greater and there will be more cost savings.

Stormwater Academy: Green Roofs CONCLUSIONS 1.Green roofs can be constructed and operated in a central Florida environment. 2.Green roofs with a cistern can be used as a stormwater treatment method. 3. The average discharge coefficient is about 0.5 for rainfall of 1 inch. The effective impervious area is about ½ of the roof area. 4. There are many other benefits such as reduction in heat islands, carbon dioxide, noise, and very real psychological benefits.

Stormwater Academy: Green Roofs More CONCLUSIONS 5.In terms of pollution and volume control, vegetated roofs are better than non vegetative ones. 6.ET rates are higher in “summer periods” relative to “winter periods” thus irrigation rates can be reduced during winter time periods. 7.Black and Gold Nuggets™ are very effective for water quality improvement. 8.LEED certification points can be attained with green roofs.

Florida: Green Roofs For more Information: Marty Wanielista, For web cam and other publications:

Questions and Comments