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The Greening of the Rooftop
Why Roof Green?
Dr. James L. HoffResearch DirectorCenter for Environmental Innovation in RoofingWashington, DC
Why Roof Green?
Increased Energy Efficiency
Renewable Energy Production
Cleaner Air & Water
Extended Building Life Cycle
Reduced Material Impacts
1 Billion Sq. Ft.
3 Billion Sq. Ft.
New Construction
Re-RoofingNorth 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. …
Why Roof Green?
… exceeding new commercial construction by a factor of 4!
Cool Roof Membranes Reduce Solar Loads
High “R” Insulation Reduces Energy Loss
Industry Best Practices Minimize Energy Waste
1
2
3
321
Multiple Ways to Save Energy
Why Roof Green?
Energy Efficiency
• The Present (At best)– ASHRAE 90.1-1999– “Energy Standard for Buildings…”– Basic roofing “R” values unchanged since 1973
• A Greener Future (What we can do)– 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
PresentR15
25%
25%
$306 Million
$119 Million
(-$13 Million)
(-$5 Million)
$407 Million
Green FutureR25
100%
100%
$192 Million
$71 Million
(-$30 Million)
(-12 Million)
$221 Million
$186 Million
Insulation R Value2
Cool Roof Usage3
Best Practice Usage4
Gross Heating Cost
Gross Cooling Cost
Cool Roof Adj.
Best Practice Adj.
Net Energy Cost1
Annual Savings
1Based on 4 billion square feet roof installations, assuming $0.12/KWH cooling energy cost, $1.00/therm heating energy cost, 2.0 cooling COP, and 75% heating efficiency, 20% of roofs replace existing cool roofs, 5% of roofs installed over unheated spaces, and 20% of roofs installed over non-cooled spaces. Calculations derived using the NRCA EnergyWise Calculator and DOE Cool Roof Calculator.2Actual R values vary +/- R5, depending on ASHRAE climatic zone.3A cool roof is defined as a roof offering 50% long-term solar reflectivity or the thermal equivalent for the service life of the roof.4Best practice defined as 2 or more staggered insulation board layers to minimize thermal loss at board joints.
Why Roof Green?
Energy Scenarios
$152
$17
Cool RoofsBest 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
$1.8 Billion Annually$10+ Billion Cumulatively
Annual Energy Savings for 4 Billion Square Feet of Low-Slope Commercial Roofing Installations
(2008 Dollars)
$0$200$400$600$800
$1,000$1,200$1,400$1,600$1,800$2,000
1 2 3 4 5 6 7 8 9 10
Mill
ions
of
Dol
lars
Year
Increased Insulation
Cool RoofingBest Practice
The Green Future
Savings After Ten Years
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 Cost1
Total First Year Cost (4 Billion Sq. Ft.)
Incremental Cost
Net Annual Cost(2008 Dollars)
First Year Savings
20 Year Savings2
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
… plus potential tax deductions under the 2008 Energy Tax Incentives Act !
Why Roof Green?
Renewable Energy Production
The Rooftops of the United States:
Segment:
Commercial (Flat)
Residential (Steep)
Total
Energy Potential2
Surface Area1
50 Billion Square Feet
150 Billion Square Feet
200 Billion Square Feet
50,000 Megawatts(10 Grand Coulie Dams)
1Derived from Census data2Assumes 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)
Will Demand for Solar Homes Pick Up?Builders find the savings from cheap power is making solar
homes more attractive
November 3, 2008
By Adam Aston As global financial markets melted down in October, Congress handed a gift to America's green energy industry: It renewed and broadened a set of tax credits for wind and solar power, geothermal, tidal energy, and more. The move did little to prop up eco-energy stocks, which have followed oil prices down. But the news did send a positive jolt to one of the economy's darkest sectors: homebuilding. Or, more specifically, solar-powered homes. Consumers recognize that green homes "save money month in, month out," says Rick
Estimated minimum pretax annual rate of return for a residential solar system in California and many other states, starting in 2009.
Why Roof Green?
Renewable Energy Production
15%
Why Roof Green?
Other Environmental Benefits
Daylighting
Heat Island Reduction
Storm Water Retention
Extended Life Cycle Design Material
Recycling