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Published byGordon Sanders Modified over 9 years ago
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The Greening of the Rooftop Module 5 Why Roof Green?
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Few Major Building Systems Can Provide As Many Energy and Environmental Benefits …
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Increased Energy Efficiency Renewable Energy Production Cleaner Air & Water Extended Building Life Cycle Reduced Material Impacts Why Roof Green? Energy / Environmental Benefits
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Why Roof Green? … And Few Major Building Systems Are Being Installed as Frequently as Roofs
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1 Billion Sq. Ft. 3 Billion Sq. Ft. New Construction Re-Roofing North American Low-Slope Roofing Market (Billions of Square Feet, 2006) Source: Roofing Industry Consensus Data Each year, 4 billion square feet of commercial roofs are installed in the U.S. … … exceeding new commercial construction by a factor of 4! Why Roof Green? The Roofing Multiplier Effect
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Cool Roof Membranes Reduce Solar Loads High “R” Insulation Reduces Energy Loss Industry Best Practices Minimize Energy Waste 1 2 3 3 21 Multiple Ways to Save Energy Why Roof Green? Energy Efficiency
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The Present (At Best) –ASHRAE 90.1-1999 –“Energy Standard for Buildings…” –Basic roofing “R” values unchanged since 1973 A Greener Future –ASHRAE 189.P (Proposed) “Standard for the Design of High-Performance Green Buildings…”” –67% average increase in minimum roof “R” values Why Roof Green? Energy Scenarios
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Present R15 25% $306 Million $119 Million (-$13 Million) (-$5 Million) $407 Million Green Future R25 100% $192 Million $71 Million (-$30 Million) (-12 Million) $221 Million $186 Million Insulation R Value 2 Cool Roof Usage 3 Best Practice Usage 4 Gross Heating Cost Gross Cooling Cost Cool Roof Adj. Best Practice Adj. Net Energy Cost 1 Annual Savings 1)Annual energy costs based on 4 billion square feet roof installations, $0.12/KWH cooling energy cost, $1.00/therm heating energy cost, 2.0 cooling COP, and 75% heating efficiency. Assumes 20% of roofs are replacing existing cool roofs, 5% of roofs are installed over unheated spaces, and 20% of roofs are installed over non-cooled spaces. Calculations derived using the NRCA EnergyWise Calculator for gross heating and cooling costs and the DOE Cool Roof Calculator for cool roof energy savings. 2)Actual R values vary +/- R5, depending on ASHRAE climatic zone. 3)A cool roof is defined as a roof offering 50% long-term solar reflectivity or the thermal equivalent for the service life of the roof. 4)Best practice defined as 2 or more staggered insulation board layers to minimize thermal loss at board joints. Why Roof Green? Energy Scenarios
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$152 $17 Cool Roofs Best Practice First Year Energy Savings: 4 Billion Sq. Ft. of Low-Slope Commercial Roofing Installations (Millions of 2008 Dollars) The Green Future First Year Savings $7 Increased Insulation Total: $186 Million
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$1.8 Billion Annually $10+ Billion Cumulatively Annual Energy Savings for 4 Billion Square Feet of Low-Slope Commercial Roofing Installations (2008 Dollars) Millions of Dollars Year Increased Insulation Cool Roofing Best Practice The Green Future Savings After Ten Years
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Present $5.00 / Sq. Ft. $20 Billion $407 Million Green Future $5.65 / Sq. Ft. $22.6 Billion $2.6 Billion $221 Million $186 Million $6.8 Billion 13.1% Unit Installed Cost 1 Total First Year Cost (4 Billion Sq. Ft.) Incremental Cost Net Annual Cost (2008 Dollars) First Year Savings 20 Year Savings 2 Average Annual ROI (1) Cost data provided from survey conducted by TEGNOS Research, Inc. (2) Assumes energy costs will increase 6% annually above non-energy core inflation rate The Green Future Economic Return
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Why Roof Green? Renewable Energy Production
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Why Roof Green? Renewable Energy Production The Rooftops of the United States: Segment: Commercial (Flat) Residential (Steep) Total Energy Potential 1 Surface Area 75 Billion Square Feet 150 Billion Square Feet 225 Billion Square Feet 75,000 Megawatts (14 Grand Coulie Dams) 1 Assumes 1watt average solar power production during daylight hours per square foot of suitable roof surface (225 billion square feet total roof surface X 25% suitable usage factor X 1 watt / square foot = 75,000 megawatts)
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Why Roof Green? Other Environmental Benefits Daylighting Heat Island Mitigation Storm Water Retention Extended Life Cycle Design Material Recycling
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Why Roof Green? When It Comes To …. … We’re On Top Of It! Increased Energy Efficiency Renewable Energy Production Cleaner Air & Water Extended Building Life Cycle Reduced Material Impacts
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