Ashley roof Final Report-Oct 2011

Transcription

FINAL REPORT
COMPARATIVE ROOF TESTING AT
ONONDAGA COUNTY CORRECTIONAL FACILITY
Final
October 2011
Submitted to:
Onondaga County Dept. of Correction
6660 East Seneca Turnpike
Jamesville, NY 13078-0143
Submitted by:
Ashley-McGraw Architects, PC
500 South Salina St, Suite 1100
Syracuse, NY 13202
CDH Energy Corp
PO Box 641
2695 Bingley Rd
Cazenovia, NY 13035
315-655-1063
EXECUTIVE SUMMARY
Onondaga County sought to evaluate the energy and water retention performance of green or
vegetative roofing systems relative to other conventional and energy-efficient roofing systems.
A major roof replacement project on multiple buildings at the Jamesville Correctional Facility
offered the opportunity for a side-by-side test to evaluate different roofing systems. Monitoring
equipment and instrumentation were installed to measure the performance of the different
systems. The test considered four different roofing systems:
1. A conventional roof with 4 inches of foam insulation and a black Ethylene Propylene
Diene Monomer (EPDM) membrane
2. A roof with 4 inches of foam insulation with a white Thermoplastic Polyolefin (TPO)
roof membrane.
3. A vegetative roof with 4 inches of foam insulation
4. A highly-insulated roof with 8 inches of foam insulation and a TPO roof membrane.
Onondaga County extended the design contract with Ashley McGraw Architects to complete this
testing. CDH Energy was hired to develop and implement a monitoring approach to quantify
compare the performance of the four roofing systems. Temperature sensors and other
instrumentation were installed in the roof assembly during construction in the Summer and Fall
of 2009. Continuous data collection at 15-minute intervals has continued since October 2009 to
obtain performance data to assess performance of the different roofing systems for all seasons of
the year.
The measured results showed that the TPO and vegetative roof systems had much lower roof
temperatures than the conventional EPDM surface. The reduction in solar absorption reduced
solar gains in the summer but also increased heat losses during the heating season. Compared to
the EPDM membrane, the TPO roof had 30% higher heating losses and the vegetative roof had
23% higher losses. The TPO roof with extra insulation did have lower heating losses than the
EPDM roof.
Overall the TPO roof was cost neutral compared to the EPDM roof when both heating and
cooling losses are considered. The vegetative roof had net cost savings of $7 per year per 1000
sq ft of roof area.
The vegetative roof retained a significant amount of the rainfall across the year. On an annual
basis only of about 20% of the measured rainfall was sent into the storm drain system.
TABLE OF CONTENTS
Introduction ..................................................................................................................................... 1
Description of Roofs ....................................................................................................................... 2
Monitoring Approach...................................................................................................................... 5
Instrumentation ........................................................................................................................... 5
Major Events During Monitoring Period .................................................................................. 12
Measured Results .......................................................................................................................... 13
Roof Thermal Performance....................................................................................................... 13
Water Retention and Drainage .................................................................................................. 27
Conclusions ................................................................................................................................... 32
Recommendations ..................................................................................................................... 32
Appendix A – Monitoring System Details
Appendix B – Comparison of Rainfall Data from Various Local Weather Stations
LIST OF FIGURES
Figure 1. Aerial View of the Four Units at Jamesville Facility ..................................................... 2
Figure 2. Description of the Green Roof on Unit 3 (Roof Garden System from Carlisle) ............. 3
Figure 3. Photos of Roofs at Onondaga County Correctional Facility (before installation) ......... 3
Figure 4. Photos of Roofs at Onondaga County Correctional Facility (after installation) ............ 4
Figure 5. Thermocouple installations TRI and TRO ..................................................................... 6
Figure 6. Thermocouple Installation TAI ....................................................................................... 6
Figure 7. Detailed Drawing of Thermocouple Locations at each Station (the colored lines
indicate how the thermocouple wires are routed through assembly and back to the
datalogger) .............................................................................................................................. 7
Figure 8. Unit 1 Station Positions (‘O’ is the datalogger, ‘X’ is the thermocouple position) ....... 8
Figure 9. Unit 2 Station Positions (‘O’ is the datalogger, ‘X’ is the thermocouple position) ....... 8
Figure 10. Unit 3 Station Positions (‘O’ is the datalogger, ‘X’ is the thermocouple position) ..... 9
Figure 11. Unit 4 Station Positions (‘O’ is the datalogger, ‘X’ is the thermocouple position) ..... 9
Figure 12. Vegetative Roof Mockup with Rain Gauge to Measure Water Drainage ................... 11
Figure 13. Green Roof Mockup on Unit 2 ................................................................................... 12
Figure 14. November 9, 2009, Temperature Profiles, Insolation Profile, and Resulting Heat Loss
Profile .................................................................................................................................... 14
Figure 15. Comparing Heat Transfer Rates for A (solid) and B (dotted) Locations on Each Unit
............................................................................................................................................... 15
Figure 16. Roof Temperature (TRO) and Heat Loss Profiles for Summer Conditions .............. 17
Figure 17. Roof Temperature (TRO) and Heat Loss Profiles for Fall Conditions ...................... 18
Figure 18. Roof Temperature (TRO) and Heat Loss Profiles for Winter Conditions ................. 19
Figure 19. Roof Temperature (TRO) and Heat Loss Profiles for Spring Conditions ................. 20
Figure 20. Daily Heat Loss Compared to Daily Outside Temperature........................................ 22
Figure 21. Plot of Monthly Heat Transfer with Four Roofing Systems ...................................... 24
Figure 22. Temperature Profiles, Heat Loss Profiles, and Rainfall/Drainage for December 2010
............................................................................................................................................... 25
Figure 23. Monthly Drainage Rate versus Rainfall (WUG data, Airport).................................... 28
Figure 24. Percentage of Monthly Drainage/Rainfall (WUG) Compared to Insolation .............. 29
Figure 25. Impact of Rainfall on Measured Soil Moisture Content ............................................ 30
Figure 26. Comparing the Impact of Roof Moisture Content on Roof Temperatures ................. 31
LIST OF TABLES
Table 1. Construction Details for the Roofs on Each Unit ............................................................. 2
Table 2 Instrumentation Installed for EACH Measurement Station .............................................. 6
Table 3. Instrumentation for Additional Measurements .............................................................. 10
Table 4. Summary of Major Events During Monitoring Period .................................................. 12
Table 5. Summary Days Included in the Plots Below ................................................................. 16
Table 6. Monthly Heat Loss Rate ................................................................................................ 23
Table 7. Annual Heating Load and Costs for Each Unit .............................................................. 26
Table 8. Monthly Rainfall and Drainage Data Along with Weather Conditions......................... 27
Introduction
Introduction
Onondaga County sought to evaluate the energy and water retention performance of green or
vegetative roofing systems relative to other conventional and energy-efficient roofing options. A
major roof replacement project on multiple buildings at the Jamesville Correctional Facility
offered the opportunity for a side-by-side test to evaluate different roofing systems. The results
of this testing are intended to provide technical feedback and guidance to inform the county’s
decision making process for future roofing renovations for the all buildings across the county.
For this test, four different roofing systems were installed:
1. A conventional roof with 4 inches of polyisocyanurate foam insulation with a black
EPDM single ply-rubber roof membrane.
2. A conventional roof with 4 inches of poly-iso insulation with a white TPO roof
membrane.
3. A vegetated roof with 4 inches of poly-iso insulation underneath it.
4. A highly-insulated roof with 8 inches of poly-iso insulation with a white TPO roof
membrane.
A side-by-side test of these four roofing systems provided the means for thermal performance to
be quantitatively assessed for:
• White
TPO vs. conventional EPDM (1 vs. 2)
inches vs. 4 inches of insulation (2 vs. 4)
• vegetated vs. non-vegetative roof systems (3 vs. 1 or 2)
•8
CDH Energy was contracted by Ashley-McGraw Architects to develop and implement a
monitoring approach to quantify and compare the performance of the four roofing systems.
Temperature sensors and other instrumentation were installed during construction in the Summer
and Fall of 2009. The data collection system was fully vetted and commissioned by late 2009.
Continuous data collection at 15-minute intervals has continued since then to obtain performance
data to assess performance of the different roofing systems for all seasons of the year.
During the monitoring period, CDH Energy has also posted the data to a website where County
staff could review plots and tables summarizing the collected data. The database and website
was updated nightly with the newest data throughout the monitoring period. The website is
available at: www.cdhenergy.com/dataaccess.php (Click on “Comparative Roof Testing at
Onondaga County Detention Facility”).
CDH Energy Corp.
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October 2011
Description of Roofs
The four buildings or Units at Jamesville that were included in this test program are shown in
Figure 1 below. Each Unit had a different roofing system installed, as described in Table 1. All
of the roofing systems included a ½-inch layer of Georgia Pacific DensDeck™ fiberglassreinforced gypsum board between the insulation and the roof membrane. In each case the
insulation was secured to the roof using adhesive foam.
Unit 4
Unit 3
Unit 2
Unit 1
Figure 1. Aerial View of the Four Units at Jamesville Facility
Table 1. Construction Details for the Roofs on Each Unit
Location
Unit 1
Unit 2
Unit 3
Unit 4
Insulation
4 inches Poly Iso1 foam board
(R22)
(R22)
(R22 + vegetative laver)
(R45)
Surface
EPDM rubber2
TPO White3
EPDM w/ Vegetative
Assembly on top
TPO White3
Notes: 1- Polyisocyanurate foam board applied in 2-inch layers
2- Black EPDM (Ethylene Propylene Diene Monomer) single-ply rubber roof membrane
3- White TPO (Thermoplastic Polyolefin) roof membrane
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October 2011
The vegetated roofing system was the Roof Garden System by Carlisle. The assembly includes a
drainage board on top of the membrane followed by a moisture retention mat and 2-3 inches of
small aggregate. The 12 inch by 15 inch sedum tiles are place on top of the aggregate. The
drainage board includes plastic cavities or cups to retain water.
Figure 2. Description of the Green Roof on Unit 3 (Roof Garden System from Carlisle)
Figure 3 shows photos of the roofs before installation and Figure 4 shows the new roofing
systems.
View from Unit 2 looking towards Unit 3
View from Unit 3 looking towards Unit 1
Figure 3. Photos of Roofs at Onondaga County Correctional Facility (before installation)
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October 2011
View from Unit 3
(vegetative) looking
towards Unit 2 (TPO)
View from Unit 4
looking towards Unit 3
Figure 4. Photos of Roofs at Onondaga County Correctional Facility (after installation)
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October 2011
Monitoring Approach
Monitoring Approach
Several approaches to quantifying the energy impact of the different roof systems were
considered including measuring the heating energy use of the HVAC system before and after
retrofit. Ultimately the approach of measuring the temperature differences within the roof
assembly was ultimately selected as most compatible with the project schedule, building
configuration, and limited access inside the facility. Two independent monitoring stations were
installed on each roof, for a total of eight stations. Each station used a Campbell Scientific data
logger. The eight loggers were located on top of the roof, space out over several hundred yards.
A mix of hardwired and wireless networking was used to connect the loggers. Communications
outside of the building was provided by a phone modem link.
Each monitoring station was based around a Campbell Scientific CR800 or CR1000 data logger
(Station 2A uses a CR1000 to accommodate the extra data points). The data loggers were
programmed to sample all sensors once per second. Calculated averages and totals were
recorded for each 15-minute interval. After all records were created at each station, the data
logger located at 3A collected each record from all the other data loggers. That master data
logger was called and data was downloaded each night by phone modem. The data was loaded
into a database at CDH Energy for automatic verification, processing and display on the web.
Appendix A provides more details on the monitoring system. The rational for installing these
points is given below.
Instrumentation
The overall experimental approach was to measure and compare the temperatures across the
assembly for the different roofing systems in a side-by-side test. The heat transfer through the
roof surface is proportional to the temperature difference through each layer. Since all the roof
systems are exposed to the same ambient conditions, as well as similar indoor temperatures, the
performance of the different systems can be directly compared at each time.
At each monitoring station, three temperatures are collected. The top point is the roof
temperature above the insulation and below the DensDeck™ (TRO). The middle point is under
the insulation but above the deck (TRI). The third point is indoor air temperature measured just
below the ceiling in the space below (TAI). These points are compared to the outdoor air
temperature (TAO) which is measured at one location.
The measurements listed in Table 2 are taken at two separate locations (A & B) on each Unit (1,
2, 3, & 4) for a total of 8 locations. Figure 5 and Figure 6 show where the thermocouples were
installed at each station. Figure 7 schematically shows the locations of each sensor through roof
assembly. The indoor temperature sensor was difficult to fish through the roof and into the space
below. However, we were able to get at least one sensor into the space for each unit.
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October 2011
Monitoring Approach
Table 2 Instrumentation Installed for EACH Measurement Station
Point
Description
Instrument
TRO
Roof Temperature
(on top of insulation, under roof brd)
Roof Temperature
(under roof insulation, above deck)
Indoor Temperature
(just below the roof)
Type-T
Thermocouple
Type-T
Thermocouple
Type-T
Thermocouple
TRI
TAI
Eng
Units
ºF
Locations
At each station
ºF
At each station
ºF
At each station
Insulation
Board
Thermocouple installed above the insulation
and below the dense deck for location 1B
(TRO)
Thermocouple installed on top of Roof Deck
(TRI ) - Before Insulation is Installed
Figure 5. Thermocouple installations TRI and TRO
Thermocouple installed just below the ceiling for
Location 4B
Thermocouple installed just below the ceiling for
Location 4A
Figure 6. Thermocouple Installation TAI
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October 2011
Monitoring Approach
Figure 7. Detailed Drawing of Thermocouple Locations at each Station (the colored lines indicate how the
thermocouple wires are routed through assembly and back to the datalogger)
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October 2011
Monitoring Approach
Figure 8. Unit 1 Station Positions (‘O’ is the datalogger, ‘X’ is the thermocouple position)
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October 2011
Monitoring Approach
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October 2011
Monitoring Approach
One of the stations (2A) also included additional measurements for the overall site. Table 3 lists
these additional measurements. A weather station was installed to measure ambient temperature
(TAO), horizontal solar flux (ISH) and rainfall (RAIN).
Table 3. Instrumentation for Additional Measurements
Point
Description
Instrument
TAO
Outdoor Temperature
ISH
Solar Flux or Insolation
(horizontal)
Green Roof Temperature
(in middle of soil layer)
Green Roof Moisture Content
(in middle of soil layer)
Rainfall
Type-T
Thermocouple
Licor LI200x
TGR
MGR
RAIN
WF
Water Flow from Green Roof
Mockup
Type-T
Thermocouple
Campbell
Scientific CS616
Texas
Electronics 525
Texas
Electronics 525
Eng
Units
ºF
Location
Station 2A
W/m2
Station 2A
ºF
Station 3A
0-1
Station 3A
Inches
Station 2A
Gal/h
Station 2A
A 4 ft by 4 ft mockup of the vegetative roof system was also created and located on the roof of
Unit 2. The purpose of this mockup was to provide the means to directly measure the water
retention of the vegetative roof assembly. Figure 12 shows the mockup with the instrumentation
added to measure its water retention performance. The instrumentation included a rain gauge
(RAIN) and as well as a modified rain gauge to measure the water flow down the drain of the
roof assembly (WF). The rain gauge included an electric heater so it could provide a reading of
snowfall as well as rain.
Figure 13 schematically shows the analysis approach. The rainfall data was compared to the
total water flow from the drain of the 4 ft by 4 ft mockup. Comparing these values provided a
direct measurement of the moisture holding ability of the green roof surface.
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October 2011
Monitoring Approach
The mockup of the
vegetative roof
assembly with rain
gauge underneath
The drain gauge (WF)
underneath the roof
mockup
WF
Figure 12. Vegetative Roof Mockup with Rain Gauge to Measure Water Drainage
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October 2011
Monitoring Approach
RAIN
Rain
Gauge
Green Roof Mockup
Roof of Unit 2
WF
Figure 13. Green Roof Mockup on Unit 2
In addition, monitoring station 3A has an extra thermocouple that is embedded in the “soil” layer
of the vegetative roof (TGR). This location also has a water content reflectometer embedded
within the vegetative assembly to measure the moisture content of the “soil” (MGR). These
sensors were installed to provide further performance information about the vegetative roof.
Major Events During Monitoring Period
Table 4. Summary of Major Events During Monitoring Period
May 2009
•
Installed embedded thermocouples for 1A
•
Installed embedded thermocouples for 1B
June 2009
•
•
•
•
•
•
September 2009
•
Vegetative roof was installed
October 2009
•
Installed data loggers for each monitoring station
•
Mockup sensors installed
•
Indoor temperature sensors installed
•
Data collection begins
November 2009
•
The phone line for data collection operational
•
The conduit for the pyranometer had been tilting; it was been straightened and reinforced.
March 2010
•
The collector on the rain gauge was knocked off the top of the device over the winter (precise date
unknown) The top was replaced.
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October 2011
Measured Results
Measured Results
The data collection system at the site was fully commissioned starting on October 22, 2009. This
section analyzes the data collected from November 1, 2009 through March 31, 2011.
Roof Thermal Performance
The calculation to determine the heat loss for each roof is made by determining the temperature
difference across the layers of insulation and dividing by the rated R-value for the installed
insulation:
TAO
Veg roof
(optional)
Deck Board
membrane
Insulation
Board
Where:
Rinsulation
- R-value for Insulation layer
(ºF-h-ft2/Btu)
q
- Heat flux through the roof
assembly (Btu/h-ft2)
TRO
q
Rinsulation
TRI
Concrete
Deck
TAI
q
=
(TRI-TRO)
Rinsulatiion
Where q is defined as positive for heat loss from the space through the roof to ambient. On each
roof, a different amount of insulation board (with an R-value of 5.7 ft2-h-°F/Btu per inch) was
installed on each Unit. The resulting R-values are given in Table 1. Because the insulation
board has very low thermal mass, the calculated heat loss values for each 15-minute interval
determined by this method are expected to provide a representative estimate of the dynamic (or
time-varying) heat transfer through the roof.
Figure 14 shows the temperatures, insolation, and resulting roof heat flux for the four different
roofs during a sunny Fall day (November 9, 2009). The top of the insulation for the EPDM
membrane is at a much warmer temperature on this day since more heat is absorbed from the
sun. The TPO roofing surface significantly reduces this impact as expected. The vegetative roof
provides thermal mass that smoothes out the fluctuations across the daily cycle.
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October 2011
Measured Results
Ambient Temperature, Top of Insulation, Bottom of Insulation, Indoor Temperature
Unit 1: 4 in, EPDM
Unit 2: 4 in, TPO
80
Temperature (F)
Temperature (F)
100
80
60
40
70
60
50
40
20
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
8 9
30
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
10
8 9
Unit 4: 8 in, TPO
80
80
70
70
Temperature (F)
Temperature (F)
Unit 3: 4 in, Veg
60
50
60
50
40
40
30
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
30
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
8 9
10
8 9
200
0
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
8 9
10
2
Heat Loss (Btu/ft^2-h)
400
Insolation (W/m^2)
10
0
Unit 1: 4 in, EPDM
Unit 2: 4 in, TPO
Unit 3: 4 in, Veg
Unit 4: 8 in, TPO
-2
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
10
8 9
10
Figure 14. November 9, 2009, Temperature Profiles, Insolation Profile, and Resulting Heat Loss Profile
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October 2011
Measured Results
Figure 15 shows that the heat transfer performance was very similar for the two locations or
stations on each Unit. The solid lines correspond to station A while the dotted lines correspond
to station B. Stations A and B generally showed very similar responses for each different roofing
system. Therefore the plots beyond this point in the report use the average heat transfer rates for
the A and B locations.
Insulation Layer
1.5
Heat Loss Rate (Btu/ft^2-h)
1.0
0.5
0.0
-0.5
-1.0
-1.5
22:
Unit 1: 4 in, EPDM
Unit 2: 4 in, TPO
Unit 3: 4 in, Veg
Unit 4: 8 in, TPO
0:
2:
4:
6:
8:
10:
12:
14:
16:
18:
20:
22:
8
9
Nov
2009
0:
10
Figure 15. Comparing Heat Transfer Rates for A (solid) and B (dotted) Locations on Each Unit
The series of plots shown in Figure 16 through Figure 19 below compare the performance of the
four roofing systems in the various seasons. In each case, specific days were selected to
represent or highlight a condition common to that season.
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October 2011
Measured Results
Table 5. Summary Days Included in the Plots Below
Season
Summer, Figure 16
Fall, Figure 17
Winter, Figure 18
Spring, Figure 19
Date
May 29, 2010
May 16, 2010
May 12, 2010
November 2, 2010
November 9, 2010
January 30, 2010
January 24, 2011
January 19, 2011
April 17, 2010
April 14, 2010
Condition
Summer, Sunny, 71F
Summer, Sunny, 59F
Summer, Cloudy, 44F
Fall, Sunny, 38F
Fall Cloudy, 40F
Winter, Sunny 2F, after notable melt
Winter, Sunny 3F, min temp -13F
Winter, Cloudy, 25F
Spring, Morning, 41F
Spring, Sunny, 49F
Summer Days
Figure 16 compares roof temperatures (i.e., at top of insulation) and heat loss rates for three
different summer days. On the sunny days the roof temperature for the EPDM roof is more than
50ºF hotter than the TPO surface. The vegetative roof was even 20ºF cooler than the TPO
surface presumably due to evaporation at the surface. The thermal mass of the vegetative
assembly above the temperature sensor (TRO) also mitigates heat loss and results in much less
variation in both temperature and heat loss across the day. The heat gain (or negative heat loss)
with the EPDM surface on the sunny days is considerably greater than for the other roof systems.
The EPDM roof has a summer time heat gain that is greater by 2-4 Btu/h per square foot (or
about 0.2-0.3 tons per 1000 sq ft) than the other roofing systems. Adding the 4 inches of
insulation with the TPO membrane reduces the peak cooling load by about 0.5 Btu/h per square
foot (or about 0.04 tons per 1000 sq ft).
Fall Days
Figure 17 shows the profiles for two fall days. Even on cloudy days the heat gain with the
EPDM roof increases surface temperatures by 20-30°F.
Winter Days
Figure 18 shows profiles for several winter days. The temperature just under vegetative roof
stays in 30-40F range regardless of ambient conditions, presumably because of its thermal mass
and its ability to retain snow cover. The cloudy winter day with snow cover showed the
temperature just under the vegetative roof remaining near 40F while the other roofs have surface
temperatures very near the freezing mark – as would be expected for a snow-covered roof. This
implies the vegetative layer is some thermal resistance by raising the freezing layer above the
roof surface.
Spring Days
Finally, Figure 19 shows profiles for some spring days. The impact of a rain event on this plot is
apparent for one of the days.
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October 2011
Measured Results
Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO
Summer, Sunny, 71F
Summer, Sunny, 71F
2
160
Temperature (F)
140
120
100
80
60
40
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
28 29
1
0
-1
-2
-3
-4
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
30
28 29
Summer, Sunny, 59F
Summer, Sunny, 59F
4
Temperature (F)
160
140
120
100
80
60
40
20
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
15 16
2
0
-2
-4
-6
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
17
15 16
Summer, Cloudy, 44F
Summer, Cloudy, 44F
70
60
50
40
30
20
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
11 12
17
4
90
80
Temperature (F)
30
2
0
-2
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
13
11 12
13
Figure 16. Roof Temperature (TRO) and Heat Loss Profiles for Summer Conditions
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October 2011
Measured Results
Fall, Sunny, 38F
Fall, Sunny, 38F
3
Temperature (F)
100
80
60
40
20
0
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
1 2
2
1
0
-1
-2
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
3
1 2
Fall, Cloudy, 40F
Fall, Cloudy, 40F
2.0
Temperature (F)
65
60
55
50
45
40
35
30
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
8 9
3
1.5
1.0
0.5
0.0
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
10
8 9
10
Figure 17. Roof Temperature (TRO) and Heat Loss Profiles for Fall Conditions
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October 2011
Measured Results
Winter, Sunny, 2F, notable melt prior
Winter, Sunny, 2F, notable melt prior
4
Temperature (F)
40
30
20
10
0
-10
-20
-30
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
29 30
2
0
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
31
29 30
Winter, Sunny, 3F, Min temp of -13F
Winter, Sunny, 3F, Min temp of -13F
3.5
Temperature (F)
40
30
20
10
0
-10
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
23 24
3.0
2.5
2.0
1.5
1.0
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
25
23 24
Winter, Cloudy, 25F
40
35
30
25
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
18 19
25
Winter, Cloudy, 25F
45
Temperature (F)
31
20
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
18 19
20
Figure 18. Roof Temperature (TRO) and Heat Loss Profiles for Winter Conditions
CDH Energy Corp.
19
October 2011
Measured Results
2.0
Temperature (F)
60
55
50
45
40
35
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
16 17
Rain
1.5
1.0
0.5
0.0
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
18
16 17
Spring, Sunny, 49F
Spring, Sunny, 49F
4
Temperature (F)
160
140
120
100
80
60
40
20
0
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
13 14
18
2
0
-2
-4
22: 0: 2: 4: 6: 8: 10: 12: 14: 16: 18: 20: 22: 0:
15
13 14
15
Figure 19. Roof Temperature (TRO) and Heat Loss Profiles for Spring Conditions
CDH Energy Corp.
20
October 2011
Measured Results
Figure 20 plots the integrated heat loss for each day versus the daily ambient temperature. Each
symbol corresponds to a day and each roof system is shown as a different color. Each daily
value is average of the A and B locations on each roof. All the roof systems show the expected
trend of more heat loss at lower outdoor temperatures.
The EPDM roof on Unit 1 with 4 inches of insulation has the most heat gain the summer and
nearly the highest amount of heat loss in the winter. The TPO roof on Unit 2 with 4 in of
insulation has less heat gain the summer – as expected. However the TPO roof also shows more
heat loss in the winter, presumably when the roof is clear of snow. The TPO roof with extra
insulation also shows the expected reduction in heat transfer.
All the roof surfaces show the impact of snow on the roof in the winter – though this effect is
most pronounced for the vegetative roof. The heat loss flattens out once the ambient temperature
drops below 35°F or so on some days because the phase change associated with snow on the roof
tends to hold the roof surface at a constant temperature near the freezing point. There is more
scatter at these temperatures since the heat transfer performance is much different whether the
roof surface is snow covered or exposed. The highly-insulated TPO roof shows less variation
and a more linear pattern because the phase change impact of freezing and thawing is not
apparent until much lower ambient temperatures are reached.
CDH Energy Corp.
21
October 2011
Measured Results
60
Impact of
Snow Cover
Heat Loss (Btu/ft^2-day)
40
Unit 1: 4 in, EPDM
Unit 2: 4 in, TPO
Unit 3: 4 in, Veg
Unit 4: 8 in, TPO
20
Heat Loss
0
Heat Gain
-20
-40
0
20
40
60
Outdoor Temperature (F)
80
100
Figure 20. Daily Heat Loss Compared to Daily Outside Temperature
CDH Energy Corp.
22
October 2011
Measured Results
Table 6 shows the result of integrating the heat loss over each month for the four roofing
systems. Figure 21 shows a plot of this data for 2010. From a heating season perspective, the
EPDM membrane provides a benefit of lower overall heat loss in the winter (October to April)
because of the solar gain. The heat loss with the TPO and vegetative roof are actually 30% and
23% greater when using the same insulation level. Adding 4 inches of insulation with a TPO
surface reduces the heat loss by 11% compared to the conventional roof.
In the cooling season1 the TPO and vegetative roofs reduce the heat gain to the roof compared to
the EPDM roof. The added roof insulation has only modest impact on the heat gain compared
once a TPO membrane has been used (the impact of insulation would have much greater had
insulation been added to the EPDM surface).
Table 6. Monthly Heat Loss Rate
Heat Loss (Btu/ft^2)
Unit 1
4 in EPDM
Month
November-09
675.2
December-09
1,063.2
January-10
1,089.5
February-10
939.6
March-10
629.8
April-10
138.8
May-10
(178.1)
June-10
(261.0)
July-10
(437.9)
August-10
(302.7)
September-10
(8.8)
October-10
394.8
November-10
724.2
December-10
968.7
January-11
970.8
February-11
879.4
2010 Htg Season
4,885.5
(Oct to April)
2010 Clg Season
(May to Sep)
(1,188.5)
Unit 2
4 in TPO
930.2
1,253.3
1,231.3
1,043.6
900.5
496.9
248.0
75.4
(22.2)
34.4
306.7
641.0
946.5
1,101.0
1,178.0
1,074.0
6,360.8
1,475.3
30%
Unit 3
4 in Veg
815.8
1,078.4
1,090.0
999.0
883.9
550.2
339.3
178.5
135.8
174.5
313.3
621.6
874.8
1,013.5
1,035.6
942.2
6,032.8
1,147.4
23%
Unit 4
8 in TPO
603.1
823.1
824.1
728.1
623.6
379.4
216.3
117.5
59.6
83.6
221.0
445.9
636.2
729.2
734.1
679.1
4,366.6
(518.8)
-11%
642.2
1,830.7
1,141.3
2,329.9
698.0
1,886.5
1
While the correctional facility has does not have cooling, we completed an analysis to assess the impact of the roof
systems assuming the facility did have cooling.
CDH Energy Corp.
23
October 2011
Measured Results
1,400
Unit 1: 4 in EPDM
1,200
Heat Loss (Btu/ft^2)
Unit 2: 4 in TPO
1,000
Unit 3: 4 in Veg
800
Unit 4: 8 in TPO
600
400
200
Heat Loss
-
Heat Gain
(200)
(400)
-10
De
c
-10
No
v
0
Oc
t-1
-10
Se
p
-10
Au
g
10
Ju
l-
-10
Ju
n
0
y-1
Ma
10
Ap
r-
r-1
0
Ma
0
Fe
b-1
Ja
n
-10
(600)
Figure 21. Plot of Monthly Heat Transfer with Four Roofing Systems
The impact of snow cover and the associated freezing and thawing at the roof surface is shown
by Figure 22. On December 1, it starting raining and the temperature dropped until the rain
turned to snow. In this case the temperatures on top of the insulation reached freezing (32oF) and
stayed there for several days. On December 4 through 9, there was precipitation but no drainage
from the roof mockup (indicating snow). The surface of all the EPDM and TPO roofs stayed
near 32oF, indicating freezing at the roof surface. The temperature probe under the vegetative
roof never reached freezing and started to get warmer as the snow started to build up and the
snow provided an insulating layer. The temperature inside the vegetative layer (green dotted)
did reach freezing but increased as the snow layer built up) However, while this change in
temperature is noticeable, the change in heat loss rate was modest and may even show a slight
increase in heat loss from the roof.
CDH Energy Corp.
24
October 2011
Measured Results
Temperature (F)
60
40
20
0
30
1
2
Nov Dec
3
4
5
6
7
8
9
10
11
12
13
14
15
3
4
5
6
7
8
9
10
11
12
13
14
15
3.0
2.5
2.0
1.5
1.0
0.5
0.0
30
1
2
Nov Dec
Unit 1: 4 in, EPDM, Unit 2: 4 in, TPO, Unit 3: 4 in, Veg, Unit 4: 8 in, TPO, Ambient Temperature
Water (inches)
0.25
Rainfall
Drainage
0.20
0.15
Rain
Snow
(no drainage)
0.10
0.05
0.00
30
1
2
3
December
4
5
6
7
8
9
10
11
12
13
14
15
Figure 22. Temperature Profiles, Heat Loss Profiles, and Rainfall/Drainage for December 2010
CDH Energy Corp.
25
October 2011
Measured Results
Table 7 compares the overall heating and cooling costs for the different roofs. The EPDM roof
is used as the reference or baseline; fuel use and cost savings are compared relative to that roof
system. The TPO and vegetative roofs actually result in slightly higher fuel costs. Heating costs
increase by $18 and $14 per year per 1000 sq ft assuming and 80% efficient heating system and a
gas cost of $1.00 per therm. The TPO roof with extra insulation does save about $6 per year per
1000 sq ft. Comparing the results for Unit 2 and Unit 4 implies that the extra 4 inches of
insulation saves about $24 per year per 1000 sq ft.
Table 7. Annual Heating Load and Costs for Each Unit
HEATING
Unit 1
4 in EPDM
Annual Heat Load (MMBtu per 1000 sq ft)
Annual Gas Use (therms per 1000 sq ft)
Annual Cost per 1000 sq ft $
Savings per 1000 sq ft
COOLING
4.9
61.1
61
Unit 1
4 in EPDM
Reduced Cooling (ton-hrs/yr per 1000 sq ft)
Reduced Cooling Power (kWh/yr per 1000 sq ft)
Savings per 1000 sq ft
COMBINED
Unit 2
4 in TPO
$
$
NET Savings per 1000 sq ft
6.4
79.5
80 $
(18) $
Unit 2
4 in TPO
$
Unit 1
4 in EPDM
Unit 3
4 in Veg
152.6
137.3
16
Unit 2
4 in TPO
$
6.0
75.4
75 $
(14) $
Unit 3
4 in Veg
$
(2) $
Unit 4
8 in TPO
194.2
174.7
21
Unit 3
4 in Veg
7
4.4
54.6
55
6
Unit 4
8 in TPO
$
157.2
141.5
17
Unit 4
8 in TPO
$
23
Cooling costs are reduced by about $16 and $21 per year per 1000 sq ft for the TPO and
vegetative roofs respectively, assuming an overall cooling efficiency of 0.9 kW per ton and an
electric cost of $0.12 per kWh. Adding the extra 4 inches of insulation with the TPO roof had
very little impact in the cooling season.
The overall savings from the TPO roof are slightly negative, with the cooling and heating
savings essentially canceling out. The vegetative roof does result in net savings of $7 per year
per 1000 sq ft. The TPO roof with extra insulation provides the most savings ($23 per year per
1000 sq ft) since the TPO membrane helps in the summer and the extra insulation reduces heat
loss in the winter.
CDH Energy Corp.
26
October 2011
Measured Results
Water Retention and Drainage
The rain gauge under the roof mockup was calibrated to measure the volume of water draining
from the 4 ft by 4 ft section. Dividing the volume of water by the area of the mockup provides
the amount (and therefore the fraction) of total rainfall draining from the section.
Drain (in) = water volume (in3) / area (in2)
Table 8 shows the monthly rainfall and drainage data along with weather conditions for the site.
The rainfall data in Table 8 is the Weather Underground (WUG) data from Syracuse Airport.
We used this data because the rain gauge on the roof at the site malfunctioned for the part of the
period (see Appendix B). For the 12 month period ending March 2011, 48.2 inches of rain were
recorded at the airport and only 9.7 inches of that rainfall drained from the mockup roof (20%).
Therefore on an annual basis the vegetative roof system retained about 80% of the rainfall.
Table 8. Monthly Rainfall and Drainage Data Along with Weather Conditions
Average
Insolation
Rainfall Drainage Ambient
(kWh/m^2)
WUG (in) (in)
Temperature
Date
Nov-09
46.7
1.8
0.5
44.0
Dec-09
35.6
2.2
0.4
28.2
Jan-10
42.8
1.1
0.5
23.8
Feb-10
45.7
2.0
0.3
26.3
Mar-10
109.4
2.5
0.9
41.0
Apr-10
146.4
0.8
0.0
52.8
May-10
183.0
2.7
0.2
62.7
Jun-10
157.1
5.4
1.1
68.0
Jul-10
199.2
4.3
0.6
75.1
Aug-10
152.4
6.4
2.1
71.5
Sep-10
98.8
5.2
1.6
63.1
Oct-10
74.5
4.2
1.4
50.9
Nov-10
45.8
2.6
0.8
40.6
Dec-10
29.8
5.7
0.7
25.5
Jan-11
41.7
3.6
0.0
22.2
Feb-11
54.6
4.7
0.7
25.8
Mar-11
98.3
2.8
0.4
33.9
1281.6
48.2
9.7
592.1
Annual 3/10
CDH Energy Corp.
27
October 2011
Measured Results
Figure 23 is a plot comparing the monthly rainfall and drainage. The data confirm the overall
drainage rate was about 20%, but there is considerable variation from month-to-month. One of
the factors thought to drive this variation is the amount of solar energy hitting the roof surface.
Solar radiation causes more evaporation and decreases the drainage rate.
8
Drainage (in)
6
4
2
0
0
2
4
Rainfall (in)
6
8
Figure 23. Monthly Drainage Rate versus Rainfall (WUG data, Airport)
CDH Energy Corp.
28
October 2011
Measured Results
Figure 24 compares the monthly drainage fraction to the monthly solar energy. There is a weak
trend of more drainage in months with modest solar flux and less drainage with more solar flux.
Drain/Rain (%)
40
20
0
0
50
100
Insolation (kWh/m^2)
150
200
Figure 24. Percentage of Monthly Drainage/Rainfall (WUG) Compared to Insolation
The moisture content of the roof was shown to have a modest impact on overall heat transfer.
Figure 25 shows a two week period in July 2010 that occurred after a long dry period. The
measured soil moisture content starts off fairly low at 5-10% before July 23 when a rain event
occurs. This storm causes the moisture content of the vegetative assembly to reach 25%. A
second rain event a couple days later pushes the moisture content above 25%.
CDH Energy Corp.
29
October 2011
Measured Results
Precipitation (in)
0.4
Rainfall
Drainage
0.2
Soil Moisture Content (%)
0.0
18
19
July
20
21
22
23
24
25
26
27
28
29
30
31
20
21
22
23
24
25
26
27
28
29
30
31
30
25
20
15
10
5
0
18
19
July
Figure 25. Impact of Rainfall on Measured Soil Moisture Content
Figure 26 shows the impact of moisture content on roof heat transfer. The plots compares the
data for July 20 (when the roof assembly was dry) and July 27 (when the roof was moist).
These two days were selected for comparison since both the ambient temperature and solar
radiation were similar. The moisture content is clearly higher on July 27 and the resulting
temperature at the roof deck is 4-5ºF cooler.
CDH Energy Corp.
30
October 2011
1.0
Insolation (W/m^2)
100
80
60
July 20, 2010
July 27, 2010
0.8
0.6
0.4
0.2
40
22: 0: 2: 4: 6: 8: 10:12:14:16:18:20:22: 0:
0.0
22: 0: 2: 4: 6: 8: 10:12:14:16:18:20:22: 0:
25
80
20
Roof Temp (F)
Soil Moisture Content (%)
Ambient Temperature (F)
Measured Results
15
10
5
0
22: 0: 2: 4: 6: 8: 10:12:14:16:18:20:22: 0:
75
70
65
60
22: 0: 2: 4: 6: 8: 10:12:14:16:18:20:22: 0:
Figure 26. Comparing the Impact of Roof Moisture Content on Roof Temperatures
CDH Energy Corp.
31
October 2011
Conclusions
Conclusions
The vegetative roof clearly retains water and minimizes the amount of rainwater that drains from
the roof. Drainage into the storm water system is only about 20% of the rainfall on the roof.
Some modest variation was noted due to the amount of solar radiation striking the roof surface:
in the summer when the insolation is higher, the amount of water draining from the roof
decreases slightly.
The thermal performance of the four roof systems was different in summer and winter. The
EPDM surface did result in roof temperatures that were as much as 50ºF higher than the other
surfaces. This surface had higher heat gains in the summer but also more modest heat losses in
the winter. The TPO membrane significantly reduced the surface temperatures in the summer
but also resulted in greater heat losses in the heating season (since beneficial solar gains are
reduced). The vegetative roof adds thermal mass to the roof assembly that dampens the
temperature swings. Evaporation at the surface also provides cooling in the summer and swing
seasons. The vegetative roof may have also retained more snow cover more often.
Overall the TPO surface with 4 inches of insulation had 30% higher thermal losses over the
heating season and increases heating costs by $18 per year per each 1000 sq ft of roof area.
However, the reduced summer time heat gains equate to about $16 per year per 1000 sq ft in
cooling energy savings. Overall, heating losses and cooling savings tended to cancel out.
The vegetative roof added thermal mass though the loss of solar gains in the winter still resulted
in 23% higher heating losses. The estimated increase in heating costs was $14 per year per 1000
sq ft. However, the reduced summer time heat gains equate to about $21 per year per 1000 sq ft
in cooling energy savings. Overall the net heating and cooling savings are about $7 per year per
1000 sq ft.
The TPO roof with an additional 4 inches of insulation had best thermal performance. The
thermal losses from the roof in the heating season were reduced by 11%. Heating costs were
reduced by $6 per year per each 1000 sq ft of roof area. The reduced summer time heat gains
equate to about $17 per year per 1000 sq ft in cooling energy savings. Overall the combined
savings are about $23 per year per 1000 sq ft.
The impact of the additional 4 inches of insulation reduce the thermal losses by about 31%
(comparing Unit 2 and Unit 4). These heating cost savings are $24 per year per 1000 sq ft. The
insulation has only a modest impact on cooling costs when combined with the TPO membrane.
The cooling savings from adding insulation with the EPDM membrane would be more
significant.
Recommendations
Onondaga County should consider using green roofs on their facilities when water retention is
the primary objective. The vegetative roof was shown to have some thermal benefit, though
CDH Energy Corp.
32
October 2011
Conclusions
similar thermal performance probably can be achieved more cost effectively by using a TPO
membrane and/or adding additional insulation.
The TPO membrane is energy neutral in the Central New York climate. The reduction in
cooling energy use and peak cooling load is offset by the increase in thermal losses during the
heating season. If TPO roofs are considered, insulation should be added to reduce heating
energy use in the winter.
CDH Energy Corp.
33
October 2011
Appendix A
Monitoring System Details
Watlow Gordon AFEC0TA060U8200
Thermocouples
The enclosure, data-logger, MD485, and
battery for Location 1B
Conduit after installation of insulation & board
(Location 1B)
Conduit mounted to roof deck at each station
Appendix A
A-1
July 2011
Finished conduit assembly with boot and
thermocouple wires shown (Station 2B)
Finished monitoring station (2A) and
weather station (solar radiation and ambient
temperature).
Position of the CS616 sensor from 3A
Appendix A
A-2
July 2011
Network map
Location Datalogger type
1A
CR800
1B
2A
CR800
CR1000
2B
CR800
3A
CR800
3B
CR800
4A
CR800
4B
CR800
Appendix A
Pak Bus Address Points
11 Roof Temperatures and indoor
temperature
12 Roof Temperatures
21 Roof Temperatures, Weather
conditions, and Mockup
temperature
31 Roof Temperatures, Soil conditions,
Modem
temperature
temperature
temperature
A-3
July 2011
Database Setup
Point Name
LID_1A
BATTV_1A
RT_1A
TRO_1A
TRI_1A
TAI_1A
LID_1B
BATTV_1B
RT_1B
TRO_1B
TRI_1B
TAI_1B
LID_2A
BATTV_2A
RT_2A
TRO_2A
TRI_2A
TAI_2A
TAO
ISH
TSF
RAIN
WF
LID_2B
BATTV_2B
RT_2B
TRO_2B
TRI_2B
TAI_2B
LID_3A
BATTV_3A
RT_3A
TRO_3A
TRI_3A
TAI_3A
TGR
MGR
MPA
LID_3B
BATTV_3B
RT_3B
TRO_3B
TRI_3B
TAI_3B
LID_4A
BATTV_4A
RT_4A
TRO_4A
TRI_4A
TAI_4A
LID_4B
BATTV_4B
RT_4B
TRO_4B
TRI_4B
TAI_4B
Description
Logger ID Number = 11
Battery Voltage
Reference Temperature
Top of insulation
Under insulation
Indoor Temperature
Battery Voltage
Top of insulation
Under insulation
Indoor Temperature
Battery Voltage
Top of insulation
Under insulation
Indoor Temperature
Outdoor Temperature
Solar Insulation
Total Flux
Rainfall
Water Flow (Model)
Battery Voltage
Top of insulation
Under insulation
Indoor Temperature(bad)
Battery Voltage
Top of insulation
Under insulation
Indoor Temperature (bad)
Soil Temperature
Soil Moisture Content
Period Average
Battery Voltage
Top of insulation
Under insulation
Indoor Temperature
Battery Voltage
Top of insulation
Under insulation
Indoor Temperature
Battery Voltage
Top of insulation
Under insulation
Indoor Temperature
Appendix A
Unit of measureInstrument
Volts
F
F
F
F
From datalogger
From datalogger
Watlow Gordon AFEC0TA060U8200 Thermocouples
Volts
F
F
F
F
From datalogger
From datalogger
Volts
F
F
F
F
F
kW/m^2
MJ/m^s
Inches
Inches
From datalogger
From datalogger
Campbell Scientific LI200X-L10 Pyranometer
Campbell Scientific LI200X-L10 Pyranometer
Texas Electronics TR-525USW Tipping Bucket
Hydrolynx 5050 Tipping bucket
Volts
F
F
F
F
%
Volts
F
F
F
F
F
%
uSec
From datalogger
From datalogger
From datalogger
From datalogger
Campbell Scientific CS616 Water Content Reflectometer
Campbell Scientific CS616 Water Content Reflectometer
Volts
F
F
F
F
From datalogger
From datalogger
Volts
F
F
F
F
From datalogger
From datalogger
Volts
F
F
F
F
From datalogger
From datalogger
A-4
July 2011
Instrumentation Information
Instrument
Output
Watlow Gordon
AFEC0TA060U8200
Thermocouples
Campbell Scientific LI200X-L10
Pyranometer
Texas Electronics TR-525USW
Tipping Bucket
Hydrolynx 5050 Tipping bucket
Type T
Campbell Scientific CS616
Water Content Reflectometer
Appendix A
mV
Multiplier and Notes
Offset
output*9./5. + 32 converts from C to F, The thermocouple
wires with a red tag are TRI while a blue tag
indicates TRO
0.2 kW m-2 mV-1
Pulse
1/25.4
Pulse
4.455/482
square wave with
frequency depenent
on water content
A-5
Converts from mm to inches of rain
Converts from pulses to inches of rain using
the calibrated value of 73ml/tip: volume
(in^3) / area (in^2) = inches
1 Volumetric water content =
0.0663+(-0.0063*PA)+(0.0007*PA)
where PA = period average of the output
July 2011
Appendix B
Comparing Rainfall Data From Various Sources
A high-quality rain gauge with an electric heater (to convert snow into water) was
installed at the site to measure the amount of rainfall. Sometime in the winter of 20092010 the top of the rain gauge was blown off. The problem was found and corrected in
March 2010. In order to assess when the data collected by the rain gauge was correct, we
compared it to the other sources of rainfall data from area, including:
1. Weather Underground (WUG) data from Hancock International Airport and,
2. The weather station at the Syracuse Center of Excellence in downtown Syracuse.
The two sources of weather data are compared to the rooftop rain gauge at the Jamesville
in Table B-1 Some discrepancy might be expected since the location of these gauges are
different by a few miles.
The data from the period of December 2009 through March 2010 for roof gauge is not
reliable as discussed above. The COE data also had a hole in the data when the tower
was moved in mid 2010..
Table B-1. Comparison of Jamesville Roof Rain Gauge to Other Sources
11/1/2009
12/1/2009
1/1/2010
2/1/2010
3/1/2010
4/1/2010
5/1/2010
6/1/2010
7/1/2010
8/1/2010
9/1/2010
10/1/2010
11/1/2010
12/1/2010
1/1/2011
2/1/2011
3/1/2011
Measured Rainfall (in)
Jamesville
COE
WUG
Roof Downtown
Airport
2.0
2.3
1.8
0.8
1.9
2.2
0.0
1.9
1.1
0.0
2.0
2.0
0.8
3.0
2.5
1.3 0.8
2.0 2.7
6.8 5.4
4.2 4.3
7.1 6.4
5.6 5.2
4.0
2.7
4.2
2.2
2.0
2.6
2.3
1.2
5.7
0.8
0.3
3.6
2.8
1.2
4.7
2.7
1.3
2.8
Figure B-1 shows a monthly comparison between the CDH data and the WUG data for
the months after the rain gauge was fixed. During most months the two data sources are
in good agreement, with the exception of the winter periods when the CDH rain gauge
has failed.
Appendix B
B-1
July 2011
8
Winter (sensor failed)
Other Seasons
WUG-Airport Rain (in)
6
4
2
0
0
2
4
6
8
Jamesville Roof Rain (in)
Figure B-1. Comparison between Rainfall Sources
Therefore, the data from Weather Underground is used as the primary source in the
main report.
Appendix B
B-2
July 2011

Ashley roof Final Report-Oct 2011

Transcription

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