1. William Retzlaff, Ph.D. SIUE Department of Biological Sciences Susan Morgan, Ph.D., P.E. SIUE Department of Civil Engineering Serdar Celik, Ph.D. SIUE Department of Mechanical Engineering ISTC 2009 – 2010 Seminar Series on Sustainability “The Path to Curbing Global Warming: Becoming Carbon Neutral” March 18, 2010 Sustainable Benefits of Green Roofs

2. Outline Introduction Results Runoff quantity Runoff quality Thermal Summary

3. Introduction: What are they?

4. Why consider them?

5. Results: Runoff Quantity

6. Mean storm water retention (%) for study period 09/05-04/07 for green roof systems with 5, 10, 15, and 20 cm planted medium depths. (C=Control, P=Planted. Bars with same letter not significantly different at the p<0.05 level. Error bars + 1se) (Forrester 2008).

7. Mean storm water retention (%) for study period 04/07-11/07 for green roof systems with 5, 10, 15, and 20 cm planted medium depths. (C=Control, P=Planted. Bars with same letter not significantly different at the p<0.05 level. Error bars + 1se) (Woods 2009).

8. April 11, 2008 collection event. Effect of media treatments on zinc concentration (bars denote mean [zinc] and standard error, n=3-4) measured from leachate collected from empty built-in-place control roofs and from each planted media placed in 10 cm Green Roof Blocks; bars with same letter not significantly different at the p <0.05 level. F = 74.48; p < 0.0001. Results: Runoff Quality – Metals

9. Results: Runoff Quality – Solids

10. Growing Media MediaDescription ArkalyteClay heated to 1000 0 C Bottom ashAsh from coal power plant HayditeShale heated to 1000 0 C LavaVolcanic rock

11. Vegetation

12. Vegetated Media TSS 20 mg/L 120 mg/L

13. Vegetated Media Turbidity 280 NTU

14. Non-Vegetated Media Turbidity 280 NTU

15. Effect of Vegetation – Haydite 280 NTU

16. Effect of Vegetation – Bottom Ash 20 mg/L 120 mg/L

17. Results: Thermal Coupled green roof model

18. Theory Reflected irradiation Diffuse irradiation Normal direct irradiation Unit thermal resistance through all layers

19. Theory Adiabatic side walls 1-D heat transfer Heat flux through a selected combination

20. Vegetation

21. Growing Media MediaDescription ArkalyteClay heated to 1000 0 C LavaVolcanic rock PumiceVolcanic Rock

22. August 2007 Data for All Combinations

23. Peak Hours on August 12, 2007

24. Heat Flux on August 12, 2007

25. Energy Cost of a 50,000 m 2 Roof during Peak Hours

26. Summary: Runoff Quantity Green roof systems reduce storm water runoff in the Midwest. When saturated, stormwater retention of green roof systems is approximately 40 - 50%. At 10-14 day intervals between rainfall events, green roofs can retain as much as 0.75 - 1.0 inch of stormwater (no through-flow). During a “normal” St. Louis growing season, stormwater retention of green roof systems can reach 80%.

27. Summary: Runoff Quality There has been no heavy metal contamination in runoff. TSS and turbidity of the growing media and the vegetated media decrease over time. TSS and turbidity vary between media. Vegetation provides a reduction in TSS and turbidity only during the first flush.

28. Summary: Thermal The color of the growth media and the vegetation affects the thermal radiation to/from the green roof blocks significantly. The more condensed the leaves are, the better shading effect occurs, resulting in better insulation in air-conditioning seasons. Fully covered blocks act as better insulators compared to partially covered ones, due to having a higher reflectivity and a better shading effect.

29. Questions? www.green-siue.com