Reducing Peak Electric Demand with Reflective Roofs

Reducing Peak Electric Demand with Reflective Roofs International Roof Coatings Conference Philadelphia, PA July 19, 2016 James L. Hoff, DBA President, TEGNOS Research, Inc. Andre Desjarlais Program Manager, Building Envelope Research

Peak Energy Demand +33% MW 8:00 AM 3:00 PM 6:00 PM Hourly Electrical Demand New England ISO Region, July 22, 2011 Source: U. S. Energy Information Administration / ISO New England

Peak Energy Demand MW Daytime HVAC Daytime Lighting & Equipment 8:00 AM 3:00 PM 6:00 PM Base Demand Hourly Electrical Demand New England ISO Region, July 22, 2011 Source: U. S. Energy Information Administration / ISO New England

Peak Energy Demand Requires additional power plant capacity Reduces capacity utilization and return on investment Causes imbalances in the power grid Increases air pollution at a critical period of the day May result in monthly charges many times higher than base electricity rates

How Commercial Building Owners Pay for Peak Demand Two Distinct Types of Charges: Base Use: Peak Demand: Measured in total kwh used Measured in highest kw used during peak periods

Base Use v. Peak Demand 30 40 50 60 MPH 70 80 20 90 034576 5 4 10 100 0 110 Miles Driven = Base Use (kwh) Top Speed = Peak Demand (kw)

Some Utilities with Peak Demand Charges UTILITY STATE UTILITY STATE Alabama Power AL Mississippi County Electric Coop MS SRP AZ Duke Energy NC Pacific Gas & Electric CA Greenville utilities NC Southern California Electric CA Nebraska Public Power NE San Diego Gas & Electric CA Long Island Power NY Xcel Energy CO National Grid NY Florida Power & Light FL Dayton Power & Light OH Sawnee EMC GA Duke Energy OH Georgia Power GA PECO PA ConEdison IL Duquesne Power PA Duke Energy IN South Caroline Electric & Gas SC NSTAR MA Black Hills Electrical Coop SD WMECO MA Noesis TX Pepco MD ONCOR TX Otter Tail Power MN We Energy WI Source: Google search for websites with peak demand and/or demand charges

Why Peak Demand Charges? Reduces risk of brownouts and blackouts Reduces capital investment requirements Percent Change Since 2006 9% 7% 5% 3% 1% -1% -3% -5% kwh Sold kw Capacity 2006 2007 2008 2009 2010 2011 2012 Total Electrical Usage versus Total Generating Capacity, 2006-2012 Source: U.S. Energy Information Administration

Typical Commercial Electric Bill Name/Service Address Acme Enterprises Attn: Accounting Dept. 123 Main Street Hanover, IN 47243 For Inquiries Call Duke Energy 1-800-655-5555 For Account Services, please contact Betty Smith Account Number 0000-1234-05-6 Meter Number Reading Date From To Days Meter Reading Previous Present Usage Actual kw Elec 012345600 Jun 28 Jul 27 29 144441 15860 56,780 120.00 Duke Energy Rate HSND High Load Factor Sec S/v Other Charges & Credits Demand Charge Energy Charge Rider 60 Fuel Adjustment Rider 61 Coal Gassification Adj Rider 62 Pollution Control Adj Rider 63 Emission Allowance Rider 66 DSM Ongoing Rider 68 Midwest Ind Sys Oper Adj Rider 70 Reliability Adjustment Rider 71 Clean Coal Adjustment Source: Duke Energy of Indiana $ 14.0600000 $ 0.01683000 $ 0.01420700 $ 1.91436100 $ 2.04057600 $0.00032300 $ 0.00021600 $ 0.00072500 $ 0.00035700 $ 2.06452600 Total Current Electric Charges 8.12 1,687.20 955.61 806.67 229.72 244.87 18.34 12.26 41.17 20.27 250.14 $ 4,274.38 $ 4,274.38

Typical Commercial Electric Bill Name/Service Address Acme Enterprises Attn: Accounting Dept. 123 Main Street Hanover, IN 47243 Meter Number Elec 012345600 Reading Date From To Jun 28 Jul 27 For Inquiries Call Duke Energy 1-800-655-5555 For Account Services, please contact Betty Smith Days 29 Meter Reading Previous Present 144441 15860 Usage 56,780 Account Number 0000-1234-05-6 Actual kw 120.00 Base Use (56,780 kwh) Duke Energy Rate HSND High Load Factor Sec S/v Other Charges & Credits Demand Charge Energy Charge Rider 60 Fuel Adjustment Rider 61 Coal Gassification Adj Rider 62 Pollution Control Adj Rider 63 Emission Allowance Rider 66 DSM Ongoing Rider 68 Midwest Ind Sys Oper Adj Rider 70 Reliability Adjustment Rider 71 Clean Coal Adjustment $ 14.0600000 $ 0.01683000 $ 0.01420700 $ 1.91436100 $ 2.04057600 $0.00032300 $ 0.00021600 $ 0.00072500 $ 0.00035700 $ 2.06452600 8.12 1,687.20 955.61 806.67 229.72 244.87 18.34 12.26 41.17 20.27 250.14 Peak Demand (120 kw) $ 4,274.38 Total Current Electric Charges $ 4,274.38 Source: Duke Energy of Indiana

Typical Commercial Electric Bill Name/Service Address Acme Enterprises Attn: Accounting Dept. 123 Main Street Hanover, IN 47243 Meter Number Elec 012345600 Reading Date From To Jun 28 Jul 27 For Inquiries Call Duke Energy 1-800-655-5555 For Account Services, please contact Betty Smith Days 29 Meter Reading Previous Present 144441 15860 Usage 56,780 Account Number 0000-1234-05-6 Actual kw 120.00 Base Use (56,780 kwh) Duke Energy Rate HSND High Load Factor Sec S/v Other Charges & Credits Demand Charge Energy Charge Rider 60 Fuel Adjustment Rider 61 Coal Gassification Adj Rider 62 Pollution Control Adj Rider 63 Emission Allowance Rider 66 DSM Ongoing Rider 68 Midwest Ind Sys Oper Adj Rider 70 Reliability Adjustment Rider 71 Clean Coal Adjustment $ 14.0600000 $ 0.01683000 $ 0.01420700 $ 1.91436100 $ 2.04057600 $0.00032300 $ 0.00021600 $ 0.00072500 $ 0.00035700 $ 2.06452600 8.12 1,687.20 955.61 806.67 229.72 244.87 18.34 12.26 41.17 20.27 250.14 Peak Demand (120 kw) $ 4,274.38 Total Current Electric Charges $ 4,274.38 Source: Duke Energy of Indiana

Typical Commercial Electric Bill Base Use Charges Name/Service Address Acme Enterprises Attn: Accounting Dept. 123 Main Street Hanover, IN 47243 Meter Number Elec 012345600 Reading Date From To For Inquiries Call Duke Energy 1-800-655-5555 For Account Services, please contact Betty Smith Jun 28 Jul 27 Duke Energy Rate HSND High Load Factor Sec S/v Other Charges & Credits Demand Charge Energy Charge Rider 60 Fuel Adjustment Rider 61 Coal Gassification Adj Rider 62 Pollution Control Adj Rider 63 Emission Allowance Rider 66 DSM Ongoing Rider 68 Midwest Ind Sys Oper Adj Rider 70 Reliability Adjustment Rider 71 Clean Coal Adjustment Days 29 Meter Reading Previous Present 144441 15860 $ 14.0600000 $ 0.01683000 $ 0.01420700 $ 1.91436100 $ 2.04057600 $0.00032300 $ 0.00021600 $ 0.00072500 $ 0.00035700 $ 2.06452600 Base Use (kwh) 8.12 1,687.20 955.61 806.67 229.72 244.87 18.34 12.26 41.17 20.27 Usage 56,780 Account Number 0000-1234-05-6 Actual kw 120.00 250.14 $ 4,274.38 Total Base Use: $1854.32 $0.0330 / kwh 44% of Monthly Bill Total Current Electric Charges $ 4,274.38 Source: Duke Energy of Indiana

Typical Commercial Electric Bill Name/Service Address Acme Enterprises Attn: Accounting Dept. 123 Main Street Hanover, IN 47243 For Inquiries Call Duke Energy 1-800-655-5555 For Account Services, please contact Betty Smith Account Number 0000-1234-05-6 Total Peak Demand: Peak Demand Charges Meter Number Elec 012345600 Reading Date From To Jun 28 Jul 27 Duke Energy Rate HSND High Load Factor Sec S/v Other Charges & Credits Demand Charge Energy Charge Rider 60 Fuel Adjustment Rider 61 Coal Gassification Adj Rider 62 Pollution Control Adj Rider 63 Emission Allowance Rider 66 DSM Ongoing Rider 68 Midwest Ind Sys Oper Adj Rider 70 Reliability Adjustment Rider 71 Clean Coal Adjustment Days 29 Meter Reading Previous Present 144441 15860 $ 14.0600000 $ 0.01683000 $ 0.01420700 $ 1.91436100 $ 2.04057600 $0.00032300 $ 0.00021600 $ 0.00072500 $ 0.00035700 $ 2.06452600 Usage 56,780 Peak Demand (kw) 8.12 1,687.20 955.61 806.67 229.72 244.87 18.34 12.26 41.17 20.27 Total Current Electric Charges Actual kw 120.00 250.14 $ 4,274.38 $ 4,274.38 $2441.94 $20.10 / kw 56% of Monthly Bill Source: Duke Energy of Indiana

Typical Commercial Electric Bill Name/Service Address For Inquiries Call Account Number Acme Enterprises Attn: Accounting Dept. 123 Main Street Hanover, IN 47243 Meter Number Elec 012345600 Reading Date From To Jun 28 Jul 27 Duke Energy Rate HSND High Load Factor Sec S/v Duke Energy 1-800-655-5555 For Account Services, please contact Betty Smith Days 29 Meter Reading Previous Present 144441 15860 Usage 56,780 0000-1234-05-6 Actual kw 120.00 Base Use: Peak Demand: Net Billing: $0.0330 / kwh $20.10 / kw $0.075 / kwh Other Charges & Credits Demand Charge Energy Charge Rider 60 Fuel Adjustment Rider 61 Coal Gassification Adj Rider 62 Pollution Control Adj Rider 63 Emission Allowance Rider 66 DSM Ongoing Rider 68 Midwest Ind Sys Oper Adj Rider 70 Reliability Adjustment Rider 71 Clean Coal Adjustment $ 14.0600000 $ 0.01683000 $ 0.01420700 $ 1.91436100 $ 2.04057600 $0.00032300 $ 0.00021600 $ 0.00072500 $ 0.00035700 $ 2.06452600 8.12 1,687.20 955.61 806.67 229.72 244.87 18.34 12.26 41.17 20.27 250.14 Base Use: Peak Demand: 44% of Bill 56% of Bill $ 4,274.38 Total Current Electric Charges $ 4,274.38 Source: Duke Energy of Indiana

Reducing Peak Energy Demand Efficiency Improvements Building Use & Scheduling Electrical Demand Management Daylighting & Solar Energy Cool Reflective Roofing

Peak Demand Not Just a Warm Climate Issue Peak Cooling Season ( 6 Months +/-) Monthly / Annual Maximum Demand 1.2 1 0.8 0.6 0.4 0.2 0 Phoenix Minneapolis Roof-Related Air Conditioning Demand: Ratio of Monthly to Annual Peak Source: Oak Ridge National Laboratories

Peak Demand Savings Uniform Through All Climate Zones 3.0 2.5 Warmest Climate Zones PHOENIX Coldest Climate Zones BTU / 100 Ft2 2.0 1.5 1.0 0.5 0.0-0.5 MINNEAPOLIS Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7-8 Base Use Savings Peak Demand Savings Potential Roof-Related Base Use and Peak Demand Savings (by North America Climate Zone) Source: RoofPoint Energy and Carbon Calculator

Peak Demand Savings Cool Roofing Proof of Concept

Peak Demand Savings Tool Development Summary Partnerships Experiments Modeling Data vs. Model Comparisons (Validation) The Tool (Ta Taaaaaa )

Team with Metal Roof, Single Ply Membrane, and Roof Coating Associations and Their Members Federally Co-funded Peak Demand Savings Working with Industry Partners

Peak Demand Savings Measuring Thermal Performance East Tennessee Climate Reflectance and Emittance for 28 Roofs 1.5 in. of Wood Fiberboard Insulation Deck Conditioned Interior of Test Building

Measuring Thermal Performance 0.9 R53E85 (WhtA) R48E82 (WhtB) R42E56 (AlF3) R36E64 (AlNF) R34E60 (AlF2) R26E68 (AlF1) R05E90 (BUR) 0.8 0.7 Solar Reflectance 0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 120 240 360 480 600 720 840 960 1080 Days of Weathering Three years of solar reflectance data measured on six coatings and the average of two uncoated BURs.

Peak Demand Savings Modeling Thermal Performance Apply One-Dimensional Transient Heat Conduction Model STAR (Simplified Thermal Analysis of Roofs) Boundary Conditions Measured Climate Conditions Deck Temperatures Calculate Surface Temperature Roof Heat Flux

Validating the Roof Model Example comparison of membrane temperatures Membrane Temperature ( F) 180 160 140 120 100 80 60 0 2 4 6 8 10 12 14 16 18 20 22 Hours into Day (8/17/99) 24 Measure Predict x Solar Refl. R,% 53 85 48 82 34 60 26 68 36 64 42 56 5 92 5 87 Tair IR Emit. E,% Effect of ±R, ±E: ±3 F at Peak

Validating the Roof Model Example comparison of insulation heat fluxes Insulation Heat Flux, Btu/(h ft²) 25 20 15 10 5 0 0 2 4 6 8 10 12 14 16 18 20 22 24 Hours into Day (8/17/99) Measure Predict Solar Refl. R,% IR Emit. E,% 53 85 48 82 34 60 26 68 36 64 42 56 5 92 5 87 Effect of ±R, ±E: ±2Btu/(h ft²) at Peak

Comparison of Peak Heat Fluxes Predicted with TMY2 Data for Knoxville and Measured in Oak Ridge

Peak Demand Savings Creating the Tool $ = $ $ Demand Savings = savings per unit area of the roof for the period of the demand charge; Δ Demand = difference between maximum deck heat fluxes; $ Demand Charge = charge per kw of electricity, usually per month; and Efficiency at Peak Load = coefficient of performance at which the air conditioner operates to remove the peak heat flux through the deck.

Peak Demand Savings Creating the Tool = + Δ Demand = difference between maximum deck heat flux for surface R05E90 and a surface with other combinations of solar reflectance and infrared emittance HS = annual average hourly solar insolation for climates; and Apand Bp = coefficients to fit the values for Demand.

Locations Used in the Tool for the Effect of Solar Radiation Control on Peak Demand Charges Location HS[Btu/(h ft²)]* CDD65 Phoenix, AZ 76.6 3814 Miami, FL 64.9 4126 Tampa, FL 64.8 3311 Dallas, TX 65.0 2414 Knoxville, TN 55.6 1366 Boulder, CO 61.1 622 Minneapolis, MN 52.4 634 Seattle, WA 44.2 127 Quillayute, WA 40.3 8 * Annual average hourly solar insolation on a horizontal surface. Cooling degrees-days at 65 F, the annual sum of daily differences between average daily air temperature and 18 C (65 F) when average daily air temperature is more than 18 C (65 F).

Peak Demand Savings Developing the Required Fit Coefficients

Peak Demand Savings Developing the Required Fit Coefficients

Average Six-Month -Demand as a Function of Average Hourly Solar Insolation

Peak Demand Savings The Calculator Dr. Tom Petrie

Peak Demand Savings Energy Calculator Available www.ornl.gov/sci/roofs+walls/facts/ CoolCalcPeak.htm

Applying the Cool Roof Peak Calculator Model Study Composite of model cities in each North American climate zone Representative commercial building 20,000 square foot low-rise structure Heated and cooled with typical HVAC equipment (AC C.O.P. = 2.0, Furnace Efficiency = 0.70) Two construction conditions / insulation levels New insulation meeting 2012 IECC insulation levels Old insulation meeting pre-2012 IECC levels Cool roof solar reflectance (SR) = 0.60 / thermal emittance (TE) = 0.90 Solar reflectance (SR) = 0.60 Thermal emittance (TE) = 0.90 Compared to black roof with SR=0.05 and TE = 0.90 Electrical base use and demand charge identical to sample energy bill Base use: $0.033 / kwh Demand Charge: $20.10 / kw Plus natural gas for heating at $0.70 / Therm

Cool Roof Model Study New Insulation Results $2,000 $1,640 Base Use Savings Peak Demand Savings $1,500 $1,340 1,270 $1,000 $1,000 $960 $1,000 $950 $800 $620 $280 $500 $0 $640 $380 $270 $800 $150 $800 $0 $700 -$80 $600 -$320 -$500 Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 R20 R20 R20 R25 R25 R30 R35 Estimated Net Energy Savings: Cool Roof Installed over New Insulation (Annual Dollars / 20,000 Square Foot Roof Area)

Cool Roof Model Study Old Insulation Results $3,000 $2,500 $3,040 Base Use Savings Peak Demand Savings $2,000 $1,600 $2,250 $1,500 $1,000 $500 $0 $1,440 $1,400 $850 $1,870 $1,490 $1,360 $1,280 $510 $210 $1,220 $1,150 $880 $1,220 $1,200 $1,200 $0 -$50 -$320 -$500 Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 R10 R15 R15 R15 R15 R15 R15 Estimated Net Energy Savings: Cool Roof Installed over Old Insulation (Annual Dollars / 20,000 Square Foot Roof Area)

The Bottom Line: Reflective Roofs and Peak Energy Demand Savings possible in all climates and conditions studied Zone 1 through Zone 8 New roofs or roof recovers All levels of roof insulation Peak demand drives the savings Over 50% in all climate zones Up to 100% in the coolest climate zones