Green Roofs: aesthetic and funtional

Simon Schreier, Department of Plant and Environmental Science

The problem: land cover change

Aerial view of Clemson University (Google Maps: www.maps.google.com)

The problem: storm water runoff

Inundated green space, University of Wisconson, Madison

The problem: heating and cooling

Total energy expenditures, Clemson University (Facilities Department)

The solution!

Green roofs! Green roofs galore!

The benefits

• Reduce runoff– Castelon et al. 2010

• Provide habitat– Dvorak and Volder 2010

• Cool and insulate– Carpenter and Kaluvakolanu 2011

Runoff comparison of green and conventional roof

Heat flow across green and conventional roofs

Approach

Consider the roof like a degraded habitat that has cross the abiotic threshold

≈

Reference habitat

Two approaches1) Find natural habitat most similar in structure2) Experimentally determine community

assemblages on a variety of substrates

CompromiseSet up a number of test pots using a variety of

growth media. Allow some to be colonized naturally, plant others with presumptive successful vegetation

Construction

1) Retrofit roof for waterproofing

2) Permeable later for drainage

3) Growth media (~10 cm)

4) Plants

MonitoringRemote sensors

-soil saturation-water flow-heat flow

Information processing-Real-time analysis-comparison with

pre- retrofit data-determine efficiency

-Adjustment and maintenance of speciescomposition and physical characteristics

CostsComponent Costs Cost Factors

Design & Specifications 5 - 10 % (of total roofing cost) The size/complexity of the project and the number/type of consultants needed.

Project Administration & Site Review 2.5 - 5 % of total roofing cost The size/complexity of the project and the number/type of consultants needed.

Re-roofing with root-repelling membrane

$ 10.00 - $15.00 / ft2 The type of existing roof, type of new roof system, and roof accessibility.

Green Roof System (drainage, filtering, paving, growing medium)

$ 5.00 - $10.00 / ft2

 Growing medium (type and depth), pavers (size and type), and square footage of the green roof (project size).

Plants $ 1.00 - $3.00 / ft2 Season of installation, type of plants, and size of seeds being planted.

Installation and Labor 

$ 3.00 - $8.00 / ft2 Equipment necessary to move materials on to the roof (E.g. crane, if rented is: $ 4,000.00 /day), project size, design, and planting methods.

Maintenance $ 1.25 - $2.00 / ft2 Project size, installation schedule, irrigation system, and plants (type and size) used.

Irrigation System $ 2.00 - $4.00 / ft2 Since extensive roofs require little irrigation (E.g. sprinkler system or drip system), this component is optional.

Total cost per square foot… $25-$48Usable roof area, assuming 5% of total campus area is usable… 1,100,000

Cost to green all roofs... $28 to $52 million

Benefits

• $1 to $2.1 million annual savings• 10% to 20 % overall decrease in energy usage• Unique habitat• Less fragmentation• Runoff management• Less stress on infrastructure

Thanks

• Dr. Eidson• Dr. David Kavanaugh, California

Academy of Sciences• Dr. Melissa Riley• Everyone who trusted me to

drive a van

ReferencesLatz, Karen. "Green Roof Installation." School of Freshwater Sciences. University of Wisconsin, 2005. Web. 7 Apr 2011. <http://www.glwi.freshwater.uwm.edu/research/genomics/ecoli/greenroof/roofinstall.php>. Liang, Han-Hsi, and Kuo-Tsang Huang. "Study on rooftop outdoor thermal environment and slab insulation performance of grass planted roof." International Journal of Physical Sciences. 6.1 (2011): 65-73. Print. Lundholm, Jeremy, Maclvor Scott, Zachary MacDougall, and Ranalli Melissa. "Plant Species and Functional Group Combinations Affect Green Roof Ecosystem Functions." PLoS ONE. 5.3 (2010): no pages given. Print. Maclvor, Scott, and Jeremy Lundholm. "Performance evaluation of native plants suited to extensive green roof conditions in a maritime climate." Ecological Engineering. 37.3 (2011): 407-417. Print. National Research Council. Urban Stormwater Management in the United States. Washington D.C.: The National Academies Press, 2008. Print. Oberndorfer, Erica, Jeremy Lundholm, Brad Bass, Reid Coffman, and Hitesh Doshi. "Green roofs as urban ecosystems: Ecological structures, functions, and services." Bioscience. 57.10 (2007): 823-833. Print. Peck, Stephen, and Monica Kuhn. "Design Guidelines for Green Roofs." Ontario Association of Architects (2003): Web. 7 Apr 2011. <http://www.cmhc.ca/en/inpr/bude/himu/coedar/loader.cfm?url=/commonspot/security/getfile.cfm&PageID=70146>. Thuring, Christine, Robert Berghage, and David Beattie. "Green Roof Plant Responses to Different Substrate Types and Depths under Various Drought Conditions." HortTechnology. 20.2 (2010): 395-401. Print United States Energy Information Administration.Commercial Buildings Electricity Consumption by End Use. Washington D.C.: The National Academies Press, 2007. Print.

Bogena, H.R., M. Herbst, J.A. Hulsman, U. Rosenbaum, and A Weuthen. "Potential of Wireless Sensor Networks for Measuring Soil Water Content Variability." Vadose Zone Journal. 9.4 (2010): 1002-1013. Print. Carpenter, Donald, and Preethi Kaluvakolanu. "Effect of Roof Surface Type on Storm-Water Runoff from Full-Scale Roofs in a Temperate Climate." Journal of Irrigation and Drainage Engineering. 137.3 (2011): 161-169. Print. Castleton, H.F., V. Stovin, S.B.M. Beck, and J.B. Davison. "Green roofs; building energy savings and the potential for retrofit." Energy and Buildings. 42.10 (2010): 1582-1591. Clemson University. “Energy Consumption and Costs.” Department of University Facilities (2010): Web. 7 Apr 2011. http://www.clemson.edu/facilities/energy-awareness/consumption.html Dvorak, Bruce, and Atrid Volder. "Green roof vegetation for North American ecoregions: A literature review." Landscape and Urban Planning. 96.4 (2010): 197-213. Print. Fioretti, R. , A. Palla, L.G. Lanza, and P. Principi. "Green roof energy and water related performance."Building and Environment. 45.8 (2010): 1890-1904. Print. In-Hea, Kim, Huh Keun-Young, Shin Hyeon-Cheol, and Park Nam-Chang. "Assessment of Plant Growth and Soil Properties of Extensive Green Roof System." Korean Journal of Horticultural Science and Technology. 28.6 (2010): 1057-1065. Print. Kavanaugh, David. "Introducing rare lepidoptera to the roof." Message to Simon Schreier. April 1, 2011. E-mail.

Questions?