Green Roof Pilot Study By Amanda Anderson 11 Advisor: Randy Chambers

Green Roof Pilot Study By Amanda Anderson 11 Advisor: Randy Chambers Introduction The green roof test plots project has advanced significantly in the development of its experimental design and community outreach since the beginning of my summer research. With the tables fully mature at nine months, their well-established root systems make data more comparable to a real green roof system. Water quality, insulation temperature, and runoff rate/volume data was taken for storms from June 2 to July 22. My internship also included visits to two schools in Washington D.C., George Washington University and American University, to observe their green roofs and other innovative green design elements. Looking toward the fall semester, continued work with Charlie Martino, our community partner, will provide our team the opportunity to consult for the City of Williamsburg and James City County with regard to green roof water quality for Cooke s Garden s new landscaping center. Project Summary The green roof test plots project consisted of a lot of data management, organization, and experiment revision. I tracked storm events and created corresponding spreadsheets organized chronologically with temperature, water quality, and pressure data for each of the four tables (green slanted, green flat, slated slanted, and slated flat). Pressure transducers were placed in runoff buckets to measure runoff rates. Temperature probes were placed above and below each table to measure the surface temperature and the insulative properties of the roofs. Moreover, runoff samples from each table per storm event were analyzed for nitrates, phosphates, ph, and ammonium. Storm data from the Keck weather station was referenced to make accurate estimates of rain rate, barometric pressure, and storm size. Although this report will contain 1

preliminary runoff and water quality data projections, the summer data will be archived and further analyzed by this fall s green roof team to create a more comprehensive report in the fall semester. 1 Another component of my project was visiting other universities for information about their green roofs and sustainable design ideas. I traveled to Washington D.C. the weekend of July 16 th and met with a sustainability staff member at each school. Both American University and George Washington University have made significant accomplishments in their sustainable building ventures in the past 10 years. It should be noted that neither school is doing any sort of active green roof research and installed their green roofs for more aesthetic and environmental responsibility reasons. Green tour highlights for both schools included multiple green roofs, many LEED certified or pending certification buildings, grey water irrigation systems, native landscaping, and sustainable SITES areas. Most of these sustainability projects, including the green roofs, were initiated through a top down approach; these projects seem to have actively helped bolster faculty and student support for sustainability. Unlike William and Mary, which adheres to a more bottom up scheme, both schools had their sustainability offices created by the administration without the financial support of green fees or a green endowment. It should be noted, however, that American University and George Washington University do seem to have a bit more flexibility in their capacity for sustainability projects because they are private universities. This means a larger portion of the budget can be set aside for the maintenance and construction of sustainable projects. The final aspect of my project was the community outreach element that grew out of the team s relationship with the Sharpe program. Summer meetings with our community partner, Charlie Martino, have lead to a new opportunity to work with the local government of 1 For information on specific experiment procedure please see the Spring 2010 report. 2

Williamsburg/James City County. Cooke s Gardens has plans to construct a new garden center in the coming year with a 5000 square foot green roof. The county has asked Cooke s and our team for more information about the water quality of green roofs. The county will be provided with a copy of our recent reports and will tour the tables this coming fall semester. Conclusions My summer research has largely been characterized by experimental redesign and improvement. This summer and last semester served to collect data as well as to improve the accuracy of the experiment. Collected data from the temperature probes has showed no discernable difference in the insulation properties of the tables, even though a clear difference can be felt just with a quick touch of the wood underneath the tables. As a result, no temperature graphs were included in this report. The placement and/or orientation of these temperature probes needs to be reevaluated, as the sensors are only currently measuring the air temperature underneath the tables. Because of this conclusion, new temperature sensors also had to be ordered to replace existing ones using the appropriated project funds. The old probes could not take data points over 100 degrees Fahrenheit, and with Williamsburg summer air temperatures consistently peaking above that, I needed new ones with a wider range. More temperature data needs to be collected by the team in the fall semester to test these deductions. A major breakthrough in my research came with the discovery that the barometric pressure readings from the Keck Lab weather station can be used to establish a baseline for the pressure transducers. Changes in air pressure influence the water level inside the collection buckets, and if a baseline is established, the changes in water level due to roof runoff in storms can be calculated. This information can be used to convert last semester s data into useable storm runoff rates, however, because Keck data is only taken every ten minutes, a fifth pressure probe 3

was purchased to serve as a control. Although several factors contributed to imprecise storm data, the uneven leveling of the Slated Flat has led to inaccurate runoff data till July 13th. This table had settled into the ground at an angle that led runoff to run in the opposite direction of the collection bucket. It was later adjusted and leveled. The chemical analysis of this summer s storms has produced a range of results. The green roofs tend to have more nutrients after the middle of June because of a serious lack of rain. It did not rain from June 23 rd to July 9 th, and with no hose for irrigation and temperatures being so high the green roofs did dry out. The lack of water lead to the plants release of a lot of extra nutrients into the runoff. More data should be taken in the less extreme temperatures to obtain more normal water quality data. Recommendations for the Future Looking toward the fall semester, I urge the green roof team to consider the alterations I made to the experimental procedure. I advise the group to rearrange the temperature sensors to include a little tray so that the lights are closer to the wood under the tables. This will hopefully lead to better insulation data. I also suggest that they continue to work with facilities management to create an energy savings/cost estimate for a green roof on the Daily Grind and Lodge 4 (preliminary plans for the Eco-village). Once an energy meter is installed, the team can look at kilowatt hour usage for average cooling/heating degree days. I recommend that the team continue to take storm data, while paying particular attention to the lag times associated with each table s runoff rates. With the new pressure probe as a control, the team can more accurately get an average estimate lag time and runoff rate for every storm. Lastly, I encourage the team to keep in contact with George Washington University, 4

American University, and Virginia Wesleyan College for future green design plans and research ideas. 5

Storm Size 25 20 Storm Event Mm of Rain 15 10 5 0 6/1 6/6 6/12 6/13 6/14 6/23 7/9 7/12 7/13 7/16 7/19 7/20 Date 6

Water Runoff from Storm on June 6 0.04 Change in PSI 0.02 0.00-0.02 Green Flat Slated Flat -0.04-0.06 6/4/2010 0:00:00 6/5/2010 0:00:00 6/6/2010 0:00:00 6/7/2010 0:00:00 6/8/2010 0:00 *Slate Roofs represent 1/4 of table runoff. 7

0.08 Water Runoff from Storm on June 6 Changed in Psi 0.06 0.04 0.02 0.00-0.02 Green Slanted Slated Slanted -0.04-0.06 6/4/10 0:00:00 6/5/10 0:00:00 6/6/10 0:00:00 6/7/10 0:00:00 6/8/10 0:00:00 *Slated Roofs represent 1/4 of table runoff. 8

Water Runoff from Storms on June 11-12 -0.01-0.02 Changes in PSI -0.03-0.04-0.05-0.06-0.07-0.08 6/11/2010 0:00:00 6/12/2010 0:00:00 6/13/2010 0:00 Green Flat Slated Flat *Slated roofs collect 1/4 of table runoff. *Slate flat roof was angled opposite to direction of collection device. Fixed July 13. 9

Water Runoff from Storms on June 11-12 0.01 0.00 Slated Slanted Changes in PSI -0.01-0.02-0.03-0.04-0.05 6/10/2010 0:00:00 6/11/2010 0:00:00 6/12/2010 0:00:00 6/13/2010 0:00:00 6/14/2010 0:00 *Slated roofs collect 1/4 of table runoff. 10

Water Runoff from Storms on June 11-12 0.01 0.00 Slated Slanted Changes in PSI -0.01-0.02-0.03-0.04-0.05 6/10/2010 0:00:00 6/11/2010 0:00:00 6/12/2010 0:00:00 6/13/2010 0:00:00 6/14/2010 0:00 *Slated roofs collect 1/4 of table runoff. 11

Water Runoff from Storm on June 13 0.10 0.08 0.06 Changes in PSI 0.04 0.02 0.00-0.02-0.04-0.06 Green Flat Runoff Slated Flat Runoff -0.08 6/12/2010 23:00:00 6/13/2010 3:00:00 6/13/2010 7:00:00 6/13/2010 11:00:00 *Slated roofs collect 1/4 of table runoff. *Slate flat roof was angled opposite to direction of collection device. Fixed July 13. 12

Water Runoff from Storm on June 23 0.04 Changes in PSI 0.02 0.00-0.02 Green Flat Slated Flat -0.04-0.06 07:00:00 11:00:00 15:00:00 19:00:00 23:00:00 *Slated roofs collect 1/4 of table runoff. *Slate flat roof was angled opposite to direction of collection device. Fixed July 13. 13

Water Runoff from Storm on June 23 0.00 Green Slanted Slated Slanted -0.01 Changes in PSI -0.02-0.03-0.04-0.05-0.06-0.07 07:00:00 11:00:00 15:00:00 19:00:00 23:00:00 *Slated roofs collect 1/4 of table runoff 14

Water Runoff from Storm on June 23 0.00 Green Slanted Slated Slanted -0.01 Changes in PSI -0.02-0.03-0.04-0.05-0.06-0.07 07:00:00 11:00:00 15:00:00 19:00:00 23:00:00 *Slated roofs collect 1/4 of table runoff 15

Water Runoff from Storm on July 9 0.04 0.02 Green Slanted Slated Slanted Change in PSI 0.00-0.02-0.04-0.06 07:00:00 08:00:00 09:00:00 10:00:00 11:00:00 12:00:00 *Slated roofs collect 1/4 of table runoff. 16

Water Runoff from Storm on July 9 0.04 0.02 Green Slanted Slated Slanted Change in PSI 0.00-0.02-0.04-0.06 07:00:00 08:00:00 09:00:00 10:00:00 11:00:00 12:00:00 *Slated roofs collect 1/4 of table runoff. 17

Water Runoff from Storm on July 13 0.000-0.005 Green Flat -0.010 Change in PSI -0.015-0.020-0.025-0.030-0.035-0.040 17:00:00 21:00:00 01:00:00 05:00:00 * Slated Flat roof used for control experiment 18

Water Runoff From Storm on July 13 0.05 0.04 0.03 Green Slanted Slated Slanted Change in PSI 0.02 0.01 0.00-0.01-0.02-0.03 17:00:00 21:00:00 01:00:00 05:00:00 *Slated roofs collect 1/4 of table runoff. 19

Water Runoff From Storm on July 16-0.005-0.010 Changes in PSI -0.015-0.020-0.025-0.030 Green Slanted -0.035 13:00:00 15:00:00 17:00:00 19:00:00 21:00:00 23:00:00 * Slated Flat roof used for control experiment *Large downward dip could possibly be attributed to wind. 20

Water Runoff from Storm on July 16 0.03 0.02 Green Slanted Slated Slanted Changes in PSI 0.01 0.00-0.01-0.02-0.03-0.04 13:00:00 15:00:00 17:00:00 19:00:00 21:00:00 23:00:00 *Slated roofs collect 1/4 of table runoff. 21

Water Runoff from Storm on July 19 0.02 0.00 Change in PSI -0.02-0.04 Green Flat Slated Flat -0.06-0.08 11:00:00 12:00:00 13:00:00 14:00:00 15:00:00 16:00:00 *Slated roofs collect 1/4 of table runoff. 22

Water Runoff from Storm on July 19 0.015 Changes in PSI 0.010 0.005 0.000-0.005-0.010 Green Slanted Slated Slanted -0.015-0.020-0.025 11:00:00 12:00:00 13:00:00 14:00:00 15:00:00 16:00:00 *Slated roofs collect 1/4 of table runoff 23

ph of Flat Roof Runoff 9 8 Slated Flat Green Flat ph 7 6 5 6/1 6/6 6/12 6/13 6/14 6/23 7/9 7/12 7/13 7/16 7/19 Date 24

ph for Slanted Tables Runoff 9 Slated Slanted Green Slanted 8 ph 7 6 5 6/1 6/6 6/12 6/13 6/14 6/23 7/9 7/12 7/13 7/16 7/19 Date 25

Total Mass of Nitrogen for Flat Roofs Micromoles per Liter 2800 2600 2400 2200 2000 700 600 500 400 300 200 100 0 Slated Flat Green Flat 6/1 6/6 6/12 6/13 6/14 6/23 7/9 7/12 7/13 7/16 7/19 Date 26

Total Mass of Nitrogen for Slanted Roofs 1800 Micromoles per Liter 1600 1400 1200 1000 800 600 400 Slated Slanted Green Slanted 200 0 6/1 6/6 6/12 6/13 6/14 6/23 7/9 7/12 7/13 7/16 7/19 Date 27

Total Phosphorus for Flat Roofs 350 Slated Flat Slated Slanted Micromoles per Liter 300 100 75 50 25 0 6/1 6/6 6/12 6/13 6/14 6/23 7/9 7/12 7/13 7/16 7/19 Date 28

Total Phosphorus for Slanted Tables 500 400 Slated Slanted Green Slanted Micromoles per Liter 300 200 100 0 6/1 6/6 6/12 6/13 6/14 6/23 7/9 7/12 7/13 7/16 7/19 Date 29