Ballasted EPDM Adhered EPDM Mech. Att. EPDM Mech. Att

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Equivalent Uniform Annual Cost A New Approach to
Roof Life Cycle Analysis
James L. Hoff, DBA
Firestone Building Products
Canadian Roofing Symposium Calgary, Alberta June
5, 2007
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Life Cycle CostProblems

• How long do roofs last?
• How much do roofs cost?
• How do you compare roofs with different service
  lives?

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Life Cycle Cost ProblemsHow Long Do Roofs Last?
Average Service Life
Study Cash (1997) Schneider Keenan (1997)
EPDM 14.1 Years 17.7 Years
Asphalt BUR 17.4 Years 13.6 Years
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Life Cycle Cost ProblemsHow Long Do Roofs Last?
Manufacturers Warranty Period
System Asphalt BUR Modified Bitumen Single-Ply
Up to15 Years Type IV Felt MB Cap over Non-MB
Base 45 Mil
Up to 20 Years Type VI Felt MB Cap over MB
Base 60 Mil
Up to 30 Years See Below MB Cap over Multiple
Plies 80-90 Mil
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Life Cycle CostSystem Details / Est. Min.
Service Life
System details and warranty period based on data
from NRCA 2004-05 Low-Slope Roofing Materials
Guide (2005) and published manufacturer data.
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Life Cycle Cost ProblemsHow Much Do Roofs Cost?

• Initial Cost
• Maintenance Cost
• Replacement Cost

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Life Cycle CostStandard Life Cycle Cost Model
LCC IC MCPV RCPV Where LCC Life
cycle cost (/ sq. ft.) IC Initial Cost MCPV
Present value of all future maintenance
costs RCPV Present value of future removal and
replacement costs
In other words, how much money in todays dollars
do I need to pay all the costs associated with
this roof over its service life?
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Life Cycle CostStandard Life Cycle Cost Model
Replacement Cost
Initial Cost

Maintenance Cost
Year 1
Year 2
Year 3
Year 4
Year 5
Year N

Present Value
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Standard Life Cycle Cost Model How to Calculate
Standard LCC

• Determine System / Service Life
• Determine Cost Elements
• Initial Cost
• Annual Maintenance Costs
• Replacement Cost
• Adjust Cost Elements to Present Value
• Determine Cost of Money / Interest Rate
• Discount Replacement Cost to Present Value
• Annuitize Maintenance Cost to Present Value
• Add Adjusted Cost Elements Together

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Standard Life Cycle Cost Model Step 1 Determine
System / Service Life
System details and warranty period based on data
from NRCA 2004-05 Low-Slope Roofing Materials
Guide (2005) and published manufacturer data.
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Standard Life Cycle Cost Model Step 2 Determine
Cost Elements
Initial cost data derived from contractor survey.
Replacement and maintenance cost data derived
from Cash (1997).
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Standard Life Cycle Cost Model Step 3 Adjust
Costs To Present Value

• Determine Cost of Money
• This Example 5 Annual Interest Rate
• Discount Replacement Cost to Present Value
• Annuitize Annual Maintenance Cost to Present
  Value

Replace At 15 Years 20 Years 30 Years
PV Discount Rate 48 38 23
Service Life 15 Years 20 Years 30 Years
Initial Annuity 11 X Annual Cost 13 X Annual
Cost 16 X Annual Cost
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Standard Life Cycle Cost Model Step 4 Summarize
Adjusted Cost Elements
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Life Cycle CostStandard Life Cycle Cost Model
Life Cycle Cost at Present Value (Dollars per
Square Foot)
8.60
8.09
7.49
15 Year MB
20 Year MB
30 Year MB
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Life Cycle CostStandard Life Cycle Cost Model
Life Cycle Cost at Present Value (Dollars per
Square Foot)
8.35
7.74
7.49
15 Year EPDM (Adhered 45 mil)
20 Year EPDM (Adhered 60 mil)
30 Year EPDM (Adhered 90 mil)
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Life Cycle CostStandard Life Cycle Cost Model
Life Cycle Cost at Present Value (Dollars per
Square Foot)
15 Year System
20 Year System
30 Year System
but which system is the best investment?
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Life Cycle CostEquivalent Annual Uniform Cost
Model
EUAC A/PLCC (i,n) Where EUAC Equivalent
Uniform Annual Cost A/P Annualized cash flow or
payment ( / sq. ft.) LCC Standard Life Cycle
Cost i annual interest rate () n service
life (years)
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Life Cycle CostEquivalent Annual Uniform Cost
Model(EUAC)

..

Payment Year 1
Payment Year 2
Payment Year 3
Payment Year N
Standard LCC
In other words, what are my estimated annual
payments over the service life of this roof?
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Life Cycle CostEquivalent Annual Uniform Cost
Model
How to Calculate EUAC

• Calculate Standard Life Cycle Cost
• Calculate the Annual Payments Required to
  Finance
• Over The Service Life
• At a Defined Interest Rate

EUAC A/PLCC(i,n)
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Life Cycle CostEquivalent Annual Uniform Cost
Model
Equivalent Uniform Annual Cost (Annual Dollars
per Square Foot)
0.72
0.65
0.56
15 Year MB
20 Year MB
30 Year MB
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Life Cycle CostEquivalent Uniform Annual Cost
Model
Equivalent Uniform Annual Cost (Annual Dollars
per Square Foot)
0.72
0.62
0.54
15 Year EPDM (Adhered 45 mil)
20 Year EPDM (Adhered 60 mil)
30 Year EPDM (Adhered 90 mil)
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Life Cycle CostEquivalent Uniform Annual Cost
Ballasted
Adhered
Mech. Att.
Mech. Att.
Modified
Built-Up
EPDM
EPDM
EPDM
T'Plastic
Bitumen
Roofing
20 Year System
30 Year System
15 Year System
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Life Cycle CostConclusions

• EUAC may be very useful in comparing the value of
  roof systems with different service lives.
• Specification enhancements such as thicker
  membranes and redundant details appear to add
  tangible value.
• Using the EUAC method, the life cycle costs of
  different roofing systems appear to be very close
  over the same time frames.

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Life Cycle CostReferences
Boon, R. A. (2001).Better roofs are less
expensive. Roofing Contractor, November. Cash,
C. G. (1997). The relative durability of
low-slope roofing. Proceedings of the Fourth
International Symposium on Roofing Technology,
119-124. National Roofing Contractors
Association Rosemont, IL. Hoff, J. L. (2007)
Equivalent uniform annual cost A new approach to
life cycle cost analysis. RCI Interface, January,
2006. Fuller, S. K., Rushing, A. S. (2005).
Energy price indices and discount factors for
life-cycle cost analysis, April 1, 2005 to March
31, 2006. Annual supplement to NIST Handbook 135
and NBS special publication 709 (NISTIR
85-3273-20). Gaithersburg, MD National Institute
of Standards and Technology. 2004-05 Low-Slope
Roofing Materials Guide (2005). Rosemont, IL
National Roofing Contractors Association. Means
Building Construction Cost Data (2005). Kingston,
MA R. S. Means. Schneider, K. G., Keenan, A.
S. (1997). A documented historical performance of
roofing assemblies in the United States
1975-1996. Proceedings of the Fourth
International Symposium on Roofing Technology,
132-137. Rosemont, IL National Roofing
Contractors Association. White paper on
sustainability (2003). Building Design
Construction, November supplement.