the greening of the rooftop module 5 why roof green?
TRANSCRIPT
The Greening of the Rooftop
Module 5
Why Roof Green?
Why Roof Green?
Few Major Building Systems Can Provide As Many Energy and Environmental Benefits …
Increased Energy Efficiency
Renewable Energy Production
Cleaner Air & Water
Extended Building Life Cycle
Reduced Material Impacts
Why Roof Green?
Energy / Environmental Benefits
Why Roof Green?
… And Few Major Building Systems Are Being Installed as Frequently as Roofs
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. …
… exceeding new commercial construction by a factor of 4!
Why Roof Green?
The Roofing Multiplier Effect
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– 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 Savings1) 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
$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
Why Roof Green?
Renewable Energy Production
Why Roof Green?
Renewable Energy Production
The Rooftops of the United States:
Segment:
Commercial (Flat)
Residential (Steep)
Total
Energy Potential1
Surface Area
75 Billion Square Feet
150 Billion Square Feet
225 Billion Square Feet
75,000 Megawatts(14 Grand Coulie Dams)
1Assumes 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)
Why Roof Green?
Other Environmental Benefits
Daylighting
Heat Island Mitigation
Storm Water Retention
Extended Life Cycle Design
Material Recycling
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