Roof Savings
Calculator Overview
Joshua New, Ph.D.
Whole Building and Community Integration Group
Building Technologies Research and Integration Center
(BTRIC)
Oak Ridge National Laboratory
Joseph W. Mellott
Director of Business Development
The Garland Company
Cleveland, Ohio
Buildings use a lot of energy
US has 5% of
the world’s
population and
uses 19% of
global energy
production
Figure 1. U.S. Primary energy consumption, 2006
DOE Goal:
By 2030,
buildings should
use 50% less
energy than
2010 baseline
Source: Building Energy Data Book, U.S. DOE, Prepared by D&R International, Ltd., September 2008.
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9.00
8.00
Figure 2. Residential
energy loads attributed to
envelope and windows
7.00
Quads
6.00
5.00
4.00
Source: Building Energy Data Book, U.S.
DOE, Prepared by D&R International, Ltd.,
September 2008.
3.00
2.00
1.00
Total
Internal
Gains
Windows
(solar gain)
Windows
(conduction)
Inf iltration
Heating
Foundation
Cooling
Walls
Roof
-
5.00
2.00
1.00
3
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Total
Internal
Gains
Windows
(solar gain)
Windows
(conduction)
Ventilation
Heating
Inf iltration
Cooling
Foundation
-
Walls (2)
Source: Building Energy Data Book, U.S. DOE,
Prepared by D&R International, Ltd., September
2008.
3.00
Roof
Figure 3. Commercial energy
loads attributed to envelope
and windows
Quads
4.00
COMPUTER TOOL FOR SIMULATING
COOL ROOFS
Roof Savings Calculator (RSC)
Chris Scruton
CEC
INDUSTRY
COLLABORATIVE
R&D
R. Levinson,
H. Gilbert,
H. Akbari
4
Managed by UT-Battelle
for the U.S. Department of Energy
WBT
Joe Huang,
Ender Erdem
Marc LaFrance
DOE BT
A. Desjarlais,
W. Miller,
J. New
AtticSim (Attic Simulation) Model
CEC PIER: Demonstrations
Ft Irwin, US Army
ASTM C 1340-99 Standard For Estimating Heat Gain or
Loss Through Ceilings Under Attics
Roof & Attic Energy Balance
Petrie, T. W., K. E. Wilkes. 1998. “Effect of Radiant Barriers and Attic
Ventilation on Residential Attics and Attic Duct Systems: New Tools
for Measuring and Modeling,” ASHRAE Trans., vol. 104, 1175-1192.
Miller et al. (2007), “Natural Convection Heat Transfer in Roofs with
Above-Sheathing Ventilation.” in Thermal Performance of the Exterior
Envelopes of Buildings, X, proceedings of ASHRAE THERM X,
Clearwater, FL., Dec. 2007.
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Attic Thermodynamics
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AtticSim Benchmark at Ft Irwin
Miller, W. 2010. Field experiments to evaluate cool-colored roofing.
Task 2.5.7 CEC milestone report.
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for the U.S. Department of Energy
DOE-2.1E Whole Building Simulation Program
User
Interface
Hourly
weather
Input
Building description
LOADS
Heat gains and losses
SYSTEMS
Distribution of heating
and cooling
PLANT
PLANT
Production of heating
and cooling
ECON
Life-cycle cost analysis
Outputs — energy use and
costs, indoor conditions,
etc.
8
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Roof Savings Calculator
 Replaces:
 EPA Roof Comparison Calc
 DOE Cool Roof Calculator
 Minimal questions (<20)
 Only location is required
 Building America defaults
 Help links for unknown
information
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Roof Savings Calculator
DOE-2.1E+AtticSim
• Building Details
• HVAC efficiency and
utility prices
• Roof and Attic
Information
(base vs. comp)
• Reports energy and
cost savings
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Current building types
Torcellini et al. 2008, “DOE Commercial Building Benchmark Models”,
NREL/CP-550-43291, National Renewable Energy Laboratory, Golden CO.
Office
“Big Box” Retail
Residential
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Warehouse
AtticSim
DOE-2
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Roof Savings Calculator
www.roofcalc.com
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Roof Savings Calculator
www.roofcalc.com
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Roof Savings Calculator
www.roofcalc.com
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Roof Savings Calculator
www.roofcalc.com
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Roof Savings Calculator
www.roofcalc.com
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Roof Savings Calculator
www.roofcalc.com
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RoofCalc.com Impact
50,000+ web simulations, 150+ user feedback, 3+ million analysis runs
Average: 86 visitors/day
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for the U.S. Department of Energy
19
HPC used to verify building simulation engine of tool
enabling industry promotion of energy efficiency
DOE: Office of Science
CEC & DOE EERE: BTO
Industry & Building Owners
Industry partners install 2000+
roofs/mo, is integrating RSC into
their proposal generating system
(others expected to follow)
Potential cumulative savings
117.2 Gwh/yr ($1.6 billion/yr)
AtticSim
Engine (AtticSim/DOE-2) debugged
using HPC Science assets enabling
visual analytics on 3x(10)6 simulations
DOE-2
Roof Savings Calculator (RSC) web
site/service developed and validated
[estimates energy cost savings of
improvements to flat or sloped roofs for
any existing condition or climate]
Leveraging HPC resources to facilitate deployment of building energy efficiency technologies
20
Managed by UT-Battelle
for the U.S. Department of Energy
Goal
Establish a geographic SRI Model that
will establish the optimum substrate SRI
for each locale based on credible
validated date.
“Run the calculator backwards.”
21
Managed by UT-Battelle
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Study Parameters
• Standard Building
–
–
–
–
–
–
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40,000 square feet
Office Building
Medium Selected for all “toggles”
Actual Energy Costs from Each City Used
R-19 as Insulating Factors
Heating by Fuel – Cooling by Electric
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for the U.S. Department of Energy
Study Parameters – Cities (14) Selected
23
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Location
Electricity,
cents/kWh
Gas,
$/1000ft3
New York
17.47
12.61
Los Angeles
15.14
9.21
Chicago
11.08
7.75
Houston
11.01
8.43
Miami
11.51
17.00
Phoenix
9.98
13.01
Kansas City
8.29
10.05
Minneapolis
10.37
7.76
San Francisco
15.14
9.21
Austin
11.01
8.43
Atlanta
10.06
14.23
Baltimore
13.44
11.85
Fargo
7.26
7.38
Fairbanks
16.55
8.43
Study Parameters – Substrates (23)
Selected
Description
BUR No Coating
Mineral Mod Bit
Single Ply
Mineral Mod Bit
Metal
Aluminum Coating over BUR
Mineral Mod Bit
Coating over BUR
Metal
Aluminum Coating over BUR
Mineral Mod Bit
Coating over BUR
Metal
Single Ply
Aluminum Coating over BUR
Metal (White)
Coating over BUR (White)
Single Ply (White)
Coating over BUR (White)
Mineral Mod Bit (White)
Single Ply (White)
Coating over BUR (White)
Single Ply (White)
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Reflectance
10
25
32
33
35
43
45
49
49
55
63
63
63
64
65
70
75
76
79
81
82
85
85
Emissivity
90
88
90
92
82
58
79
83
83
45
88
86
84
80
45
85
90
87
90
80
79
90
87
SRI
6
25
35
35
35
35
55
55
55
48
75
75
75
75
65
85
93
94
100
100
100
107
107
Compared with…
• All Substrates were compared with
– 5% Reflective
– 0.90 Emissivity
– BUR Roof
25
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Disclaimer
• While DOE-2.1E] and AtticSim ASTM
Standard C 1340-04 have been validated with
comparison to empirical data, the integrated
RSC engine has not. Furthermore, it is known
to have discrepancies with previous cool
roofing studies based on engines that didn’t
incorporate heat transfer through radiation
within the attic assembly that is yet to be
reconciled.
26
Managed by UT-Battelle
for the U.S. Department of Energy
Current Results
Description
27
Reflectance Emissivity
SRI
Atlanta
Austin
Baltimore
Chicago
Fairbanks
Fargo
Houston
Kansas
City
Los
Angeles
Miami
Minneapolis New York Phoenix
San
Francisco
BUR No Coating
10
90
6
-54
0
-66
-36
-125
-99
42
-47
98
75
-53
-89
39
-68
Mineral Mod Bit
25
88
25
-422
-39
-507
-325
-941
-659
103
-368
383
276
-419
-669
70
-420
Single Ply
32
90
35
-384
71
-437
-253
-901
-660
230
-320
614
441
-382
-582
154
-494
Mineral Mod Bit
33
92
35
-574
3
-655
-407
-1302
-908
197
-477
648
463
-560
-871
118
-659
Metal
35
82
35
-883
-191
-1000
-742
-2213
-1296
60
-698
293
212
-863
-1558
74
-322
Aluminum Coating over BUR
43
58
35
-9
189
-64
-46
-237
-298
279
-45
585
372
-93
-189
294
-58
Mineral Mod Bit
45
79
55
-564
84
-657
-408
-1385
-1003
291
-475
872
594
-582
-907
216
-693
Coating over BUR
49
83
55
-413
231
-461
-250
-1154
-872
433
-345
1075
742
-441
-680
348
-640
Metal
49
83
55
-1191
-126
-1231
-837
-2855
-1697
208
-857
771
576
-1102
-1891
138
-957
Aluminum Coating over BUR
55
45
48
39
174
-35
-29
-276
-367
390
-21
825
502
-90
-202
419
-51
Mineral Mod Bit
63
88
75
-909
203
-996
-571
-2372
-1661
525
-726
1473
1105
-933
-1380
300
-1419
Coating over BUR
63
86
75
-606
334
-664
-347
-1787
-1305
607
-501
1512
1102
-659
-980
452
-1104
Metal
63
84
75
-1487
-31
-1465
-919
-3600
-2151
361
-1028
1295
986
-1356
-2198
171
-1704
Single Ply
64
80
75
-637
304
-712
-386
-1850
-1345
578
-528
1480
1067
-694
-1031
408
-1105
Aluminum Coating over BUR
65
45
65
-80
272
-160
-88
-696
-655
542
-123
1230
758
-227
-399
558
-301
Metal (White)
70
85
85
-1622
14
-1592
-967
-4005
-2422
436
-1133
1522
1211
-1502
-2353
166
-2131
Coating over BUR (White)
75
90
93
-770
417
-875
-443
-2391
-1732
767
-664
1822
1460
-900
-1261
526
-1642
Single Ply (White)
76
87
94
-840
384
-962
-502
-2547
-1829
745
-722
1808
1460
-974
-1358
471
-1720
Coating over BUR (White)
79
90
100
-812
450
-928
-471
-2571
-1862
820
-710
1906
1576
-974
-1336
553
-1825
Mineral Mod Bit (White)
81
80
100
-1025
355
-1161
-642
-3006
-2131
748
-867
1876
1556
-1175
-1634
444
-2057
Single Ply (White)
82
79
100
-819
455
-949
-494
-2643
-1912
822
-722
1934
1578
-1002
-1373
554
-1847
Coating over BUR (White)
85
90
107
-873
499
-1008
-524
-2845
-2073
905
-782
2003
1761
-1097
-1454
592
-2123
Single Ply (White)
85
87
107
-936
459
-1083
-577
-2969
-2143
871
-830
1974
1736
-1156
-1536
531
-2167
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Current Results – Not Surprising
28
Managed by UT-Battelle
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Current Results – Peak Modality
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for the U.S. Department of Energy
Current Results – Surprising
30
Managed by UT-Battelle
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Current Results
31
Managed by UT-Battelle
for the U.S. Department of Energy
Current Results
32
Location
Observed
Optimized
Condintion
Maximum
Trend
Observed
Desired SRI Savings, $
Atlanta
Minimized
0
Austin
Maximized
Baltimore
Best Observed System
Related SRI
39
Aluminum Coating over BUR
48
107
499
Coating over BUR (White)
107
Minimized
0
-35
Aluminum Coating over BUR
0
Chicago
Minimized
0
-29
BUR No Coating
0
Fairbanks
Minimized
0
-125
BUR No Coating
0
Fargo
Minimized
0
-99
BUR No Coating
0
Houston
Maximized
107
905
Coating over BUR (White)
Kansas City
Minimized
0
-21
Aluminum Coating over BUR
Los Angeles
Maximized
107
2003
Coating over BUR (White)
107
Miami
Maximized
107
1761
Coating over BUR (White)
107
Minneapolis
Minimized
0
-53
BUR No Coating
0
New York
Minimized
0
-89
BUR No Coating
0
Phoenix
Maximized
107
592
Coating over BUR (White)
San Francisco
Minimized
0
-51
Aluminum Coating over BUR
Managed by UT-Battelle
for the U.S. Department of Energy
107
0
107
0
Current Results
33
Managed by UT-Battelle
for the U.S. Department of Energy
Data taken from doe-1 calculator
• Changed Assumption R-15*
34
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Results - Similarities
• Clearly Warm Climates Still Needed Maximized SRI
–
–
–
–
35
Austin
Houston
Miami
Phoenix
Managed by UT-Battelle
for the U.S. Department of Energy
Results – Similarities +
• Clearly Warm Climates Still Needed Maximized SRI
• Cold Climates Showed Modality
–
–
–
–
–
36
Chicago
Fairbanks
Fargo
Minneapolis
San Francisco
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for the U.S. Department of Energy
Results – Switches
• Clearly Warm Climates Still Needed Maximized SRI
• Cold Climates Showed Modality
• Climates Changed from a SRI Minimized Zone to a
Maximized Zone
– Atlanta
– Baltimore
– New York
37
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Results – Surprise
• Clearly Warm Climates Still Needed Maximized SRI
• Cold Climates Showed Modality
• Climates Changed from a SRI Minimized Zone to a
Maximized Zone
• LA Showed a localized Maximum at 65 SRI
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for the U.S. Department of Energy
Current Results
39
Location
Atlanta
Austin
Baltimore
Chicago
Fairbanks
Fargo
Houston
Kansas City
Los Angeles
Miami
Minneapolis
New York
Phoenix
Observed
Optimized
Condintion
Maximized
Maximized
Maximized
Modal
Modal
Modal
Maximized
Maximized
Maximized
Maximized
Modal
Maximized
Maximized
San Francisco
Modal
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Maximum
Trend
Observed
Desired SRI Savings, $
107
1080
107
2680
107
1000
64.95
360
42.68
680
40.58
160
107
1840
107
800
107
440
107
4440
47.05
360
107
560
107
3000
39.31
200
Best Observed System
Aluminum Coating over BUR
Coating over BUR (White)
Single Ply White/Coating over BUR (White)
Aluminum Coating over BUR
Aluminum Coating over BUR
Aluminum Coating over BUR
Coating over BUR (White)
Coating over BUR (White)
Aluminum Coating over BUR
Coating over BUR (White)
Aluminum Coating over BUR
Aluminum Coating over BUR
Coating over BUR (White)
Related SRI
65
107
103.5
48
48
48
107
107
65
107
48
65
107
Aluminum Coating over BUR
48
Current Results
40
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Forward Effort
• More Data
• Model Validation
• Automate Reverse Modified Calculator
41
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Thank You Discussion