Life Cycle Assessment and the Building Envelope: Balancing

Durability & Environmental Impact

Dr. James L. HoffCenter for Environmental Innovation in Roofing

Agenda

• Sustainability: Balancing Time & Impact

• Life Cycle Assessment

• Durability

• LCA and Durability: Critical Issues

• Durability Tools for a Sustainable Future

• Recommendations Going Forward

What is Sustainability?

“A state that can be maintained at a certain level indefinitely” (Merriam-Webster Online Dictionary)

“Meeting the needs of the present without compromising the ability of future generations to meet their own needs” (U.N. Brundtland Commission, 1987)

Measuring Sustainability

When evaluating the relative sustainability of a product or a system, the key questions are:

Sustainability =ImpactTime

1. How long (time) can the product or system last?

2. What is the cost (impact) to last that long?

Sustainability: The Core Issue

TIMEIMPACT

Balancing Impact and Time

Looking at Impact:Life Cycle Assessment

(LCA)

Looking at Longevity:Durability

What is LCA?

“… a scientific approach to identify and evaluate the environmental impact of a product throughout its life cycle.”

Office of the Federal Environmental Executive (OFEE)http://ofee.gov/gs/gs.asp

What is LCA?• A Scientific Approach: Based on measurable and

predictable attributes

• To Identify & Evaluate: Intended to compare alternatives, not provide absolute values

• Focused on Impact: What is the net result to the environment?

• Throughout the Life Cycle: A “cradle-to-grave”… or “cradle-to-cradle” approach

Why is LCA Important?

• LCA is a globally recognized procedure based on established ISO standards

• LCA will be incorporated into the LEED®

Green Building Rating System in 2010 / 2011

• LCA is a necessary measure to support emerging global warming initiatives such as carbon cap-and-trade

1. Establish the Time Period

2. Describe the Life Cycle System

3. Identify & Measure the Impacts

4. Assess the Impacts

Key LCA Steps

10 Years

15 Years

20 Years

30 Years

39 ½ Years

60 Years

Typical Commercial Roof Warranty Length

U.S. Taxable Building Depreciation Period

USGBC Life Cycle Task Force Recommendation

Step 1: Establish the Time Period

Step 2: Describe the Life Cycle System

• Inputs

• Processes

• Outputs

• System Boundary

Raw Materials Acquisition

Manufacturing

Operation / Maintenance

Recycling / Waste Mgmt.

Inputs:

Raw Materials

Energy

Outputs:

Atmospheric Emissions

Waterborne Waste

Solid Waste

Co-Products

Other ReleasesSystem Boundary

Processes:

Transportation & Handling

Installation / Assembly

The Product Life Cycle

Time

Impact

Step 3: Measure the Impacts

• Identify the Significant Impacts

• Establish Meaningful Measures

Impact:

Global Warming Potential

Ozone Depletion Potential

Photochemical Oxidant Potential

Acidification Potential

Eutrification

Health Toxicity (Cancer)

Health Toxicity (Non-Cancer)

Health Toxicity (Air Pollutants)

Eco-Toxicity Potential

Linked To:

Global Climate Change

Degradation of Ozone Layer

Ground-Level Ozone

Acid Rain

Algae Blooms

Cancer Frequency

Non-Cancer Disorders

Breathing-Related Illnesses

Reproductive & Genetic Disorders

Measuring Environmental Impacts

The TRACI Model

Measuring Environmental Impacts

The TRACI Model

Meaningful Measure:

kg CO2 Equivalent

kg CFC Equivalent

kg NOX Equivalent

H+ Moles Equivalent

kg Nitrogen Equivalent

kg Benzene Equivalent

kg Toluene Equivalent

kg: DALYs Equivalent

kg 2,4-D Equivalent

Impact:

Global Warming Potential

Ozone Depletion Potential

Photochemical Oxidant Potential

Acidification Potential

Eutrification

Health Toxicity (Cancer)

Health Toxicity (Non-Cancer)

Health Toxicity (Air Pollutants)

Eco-Toxicity Potential

• Weigh the Impacts– Which impacts are most important in the assessment?

• Compare Alternatives– Which alternative provides the optimal benefit?

• Look for Improvement Opportunities– How can the impacts be reduced?

Step 4: Assess the Impacts

• Avoids Shifting of Impacts

• Allows Consideration of Trade-Offs

• Promotes Situation-Based Decisions

LCA Benefits

LCA Limitations• LCA is Expensive

– Requires time & money

• LCA is Complex– Difficult to understand & communicate

• LCA is Not Absolute– Useful for reference or comparison– Cannot by itself determine cost-

effectiveness or practicality

What is Durability?

A dictionary definition:

“… the ability to exist for a long time without significant deterioration.”

Merriam-Webster Online Dictionary

What is Durability?A building standards definition:

“… the ability of a building or any of its components to perform its required functions in its service environment over a period of time without unforeseen cost for maintenance or repair.”

Canadian Standards Association “Guideline on Durability in Buildings” (CSA S478-95, Rev. 2001)

The ability of a building or any of its components to:

1. perform its required functions

2. in its service environment

3. over a period of time

4. without unforeseen cost for maintenance or repair

What is Durability?

Roof Durability Characteristics

Performing Required Functions• Resist and re-direct moisture

• Resist air & vapor movement

• Resist thermal transfer

• Resist fire, wind, hail, and other loads

• Serve as a working platform for:– Rooftop mechanical equipment– Solar / PV installations– Garden roofing installations

Roof Durability Characteristics

In Its Service Environment

• Climatic Environment– High wind / wind-blown debris zones– Severe hail zones– Cold climates / severe freeze-thaw zones– Warm climates / high uv zones

• Operating Environment– Frequency / density of use– Occupant capabilities / attitudes– Frequency / complexity of maintenance

Roof Durability Characteristics

Over a Period of Time

Period of Time =

Intended Service Life

Roof Durability Characteristics

Without Unforeseen Cost

Implies Some Level of Cost Should Be Foreseen!

Implies Planning Is Necessary!

“The majority of green building assessment systems focus on the design of the constructed building, with little focus on the effect of the building system’s life during operation. This tendency has resulted in a failure of many rating systems to properly consider durability, lifecycle cost, and the effects of premature building envelope failures.”

Durability &Green Rating Systems

“Green Assessment Tools: The Integration of Building Envelope Durability. “ (McCay, 2008, p. 1)

Too much focus on design, too little focus on operation…

... resulting in a failure to address:

– True life cycle cost

– Risk of premature failures

Durability &Green Rating Systems

• Incorporating Vital Service Features into LCA

• Incorporating Realistic & Achievable Service Life Expectations into LCA

Balancing Impact &Durability: The Key Issues

Example:

Installing a High Density Cover Board over Low Density Roof Insulation

MembraneCover Board

Insulation

Environmental Benefits:+ Reduced Damage+ Longer Service Life+ Lower Life Cycle Impact

Environmental Costs:– Added Materials– Added Energy– Added Waste

Balancing Impact & Durability

Vital Service Functions

Thicker roofing membranes

Redundant flashing details

Will the LCA recognize the added value of such enhanced service features?

Balancing Impact & Durability

Vital Service Functions

Other Examples:

Balancing Impact & Durability

Service Life Expectations

How do we identify service life today?• Anecdotal field reports

• Opinion surveys

• Historical end-of-service studies

• Agency approval reports

• Manufacturer warranty offerings

Opinion Survey1

16.6

16.6

N/A2

14.1

No Data

System Type

Asphalt BUR

SBS Modified

PVC

EPDM

TPO

Historical Study3

13.6

17.3

N/A2

16.8 – 18.4

No Data

Agency Report4

20

20

35

20

20

Warranty Offering5

20

20

15

30

30

Data Source

1Mean service life from Cash (1997), based on an opinion survey of industry participants.2Data from the Cash & Schneider studies involved discontinued formulations of PVC that do not allow the data to be meaningful.3Mean service life from Schneider & Keenan (1997), based on end-of-service field reports.4Estimated service life from British Board of Agrément Technical Approvals (BBA, 2008):5Published warranty offerings from NRCA Low Slope Roofing Materials Guide, 2006-07, Vol. 2, Section 5 Roof Membrane Warranties.

Service Life Expectation Example:

Low-Slope Roofing SystemsEstimated Service Life (Years)

Different Estimates – Different Assumptions:

• Time Assumptions– Backward looking: Expecting no change– Forward looking: Expecting improvement

• Quality Assumptions– Uncontrolled sample: Assuming the worst– Controlled sample: Assuming the best

Durability & LCA

Service Life Expectations

The contrast between forward-looking versus backward-looking service life estimates and average versus high quality levels help identify two critical questions for the building envelope industry:

Durability & LCA

Where Do We Go From Here?

1. Should we move forward with the assumption that the building envelope components installed on the sustainable buildings of the future will be average in performance, or should the expectation be set higher?

2. And if we decide to move forward with higher expectations, how do we develop and implement processes and controls to assure this higher level of performance is attained?

Durability & LCA

Durability Tools for a Sustainable Future

• Performance Standards

• Durability Planning

Durability Tools

Performance Standards

• Prove Their Value through Research– Drawing from the past– Adding certainty to the future.

• Identify Their Value with Measurement– Providing measurable and reproducible value– Balancing environmental impact with added performance.

In order to effectively address vital service functions, performance standards must…

• Failure Analysis (e.g. Bailey & Bradford field studies)

• Destructive Testing (e.g. Koontz et al. hail testing)

• Performance Testing (e.g. ORNL thermal testing)

Performance Standards

Research Examples & Options(Low Slope Roofing)

What is the measurable value (benefit less impact) of:

– Multiple & staggered insulation layers?

– Cover boards?

– Increased membrane thicknesses?

– Redundant flashing details?

Performance Standards

Features Needing Measurable Value:

• An Up-To-Date & Active Research Agenda– To identify & address the critical “gaps”– To identify resources & funding– To monitor & measure progress

• A Research-Driven Standards Process– A consensus process … – Using research results to validate industry practice

Performance Standards and the Building Envelope

What We Need:

Durability Tools

Durability Planning

• Emphasis on Process– A management system– Similar to ISO 9000 & ISO 14000

• Emphasis on Shared Responsibility– Identifies stakeholders– Identifies roles

Durability Tools

Durability Planning and Canadian Standard S478-95

Three Basic Steps:

1. Identify Durability Determinants

2. Identify Durability Interventions

3. Develop Action Plan & Timetable

Step1: Identify Durability Determinants

• Providing the Required Functions

• In the Service Environment

• By Key System Element

Durability Planning

Canadian Standard S478-95

Step 2: Identify Durability Interventions

Durability Planning

Canadian Standard S478-95

• During Design

• During Material Selection

• During Application & Commissioning

• During Service Life

• At End of Service

Step 3: Develop Action Plan & Timetable

Durability Planning

Canadian Standard S478-95

• Periodic & Ongoing

• At Critical Specified Times

Durability Planning Matrix

Durability Planning & Green Building Envelope Design

The Service Environment

Required Functions

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Durability Planning

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Balancing Impact & Durability

Going Forward…• Try to reach agreement on realistic, but achievable service

life periods that support long-term building sustainability

• Establish an up-to-date and active industry research agenda

• Increase research activity, emphasizing key component & detail functions

• Re-invigorate standards activity with new research & new commitment

• Begin incorporating durability planning into building envelope specifications

• Continue to advocate the importance of durability

Life Cycle Assessment and the Building Envelope: Balancing

Durability & Environmental Impact

Dr. James L. HoffCenter for Environmental Innovation in Roofing