SUSTAINABLE BUILDINGS: ADDRESSING LONG-TERM BUILDING ENVELOPE DURABILITY Dr. James L. Hoff Center for Environmental Innovation in Roofing / TEGNOS Research, Inc.

Durability & Green Rating Systems Durability is a necessity to achieve long-term sustainability … … but many green building rating systems provide little assurance that durability is adequately addressed.

“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)

Durability & Green Rating Systems Too much focus on design, too little focus on operation…... resulting in a failure to address: –True life cycle cost –Risk of premature failures

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)

What is Durability? 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

Roof Durability Characteristics Perform 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 … More to Follow

Roof Durability Characteristics Without Unforeseen Cost… Implies Some Level of Cost Should Be Foreseen! Implies Planning Is Be Necessary!

Roof Durability Characteristics Without Unforeseen Cost for.. Maintenance –Frequent & ongoing –Includes inspection, assessment, service, & minor repairs Repair –Infrequent, but generally planned –Includes renovation, retrofitting, component replacement

Durability & Green Building Design The Major Issues Justifying Vital Service Functions in Green Design Assessment Incorporating Reliable Service Life Expectations into Green Design

Durability & Green Building Design Vital Service Functions Example: Installing a High Density Cover Board over Low Density Roof Insulation Membrane Cover Board Insulation Environmental Benefits: +Reduced Damage +Longer Service Life +Lower Life Cycle Impact Environmental Costs: –Added Materials –Added Energy –Added Waste

Unless the benefits of the cover board are recognized in the overall project assessment, the cover board may be viewed only as adding to environmental costs: Durability & Green Building Design Vital Service Functions Membrane Cover Board Insulation Environmental Benefits: +Reduced Damage +Longer Service Life +Lower Life Cycle Impact Environmental Costs: –Added Materials –Added Energy –Added Waste

Other Examples: Thicker roofing membranes Redundant flashing details Will the project assessment recognize the added value of such enhanced service functions? Durability & Green Building Design Vital Service Functions

Durability & Green Building Design Incorporating Vital Service Functions Performance Standards

Durability & Green Building Design 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 incorporate vital service functions, performance standards must…

Durability & Green Building Design Performance Standards Research examples & options: Failure Analysis (e.g. Bailey & Bradford field studies) Destructive Testing (e.g. Koontz et al. hail testing) Performance Testing (e.g. ORNL thermal testing)

Durability & Green Building Design Performance Standards Benefits Needing Definition: (Examples) What is the measurable value (benefit less impact) of: –Multiple & staggered insulation layers? –Cover boards? –Increased membrane thicknesses? –Redundant flashing details?

Durability & Green Building Design Performance Standards and the Roofing Industry By definition, sustainable buildings must be buildings that perform: so performance standards are more important than ever … … but without credible roofing industry performance standards, others may establish the standards for us.

Durability & Green Building Design Performance Standards and the Roofing Industry A spirit of industry cooperation is emerging that could foster expanded performance standards activities … … but credible roofing industry standards may require a much higher level of research activity and funding.

Durability & Green Building Design Performance Standards and the Roofing Industry 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 What The Industry Needs:

Durability & Green Building Design Service Life Expectations How do we identify service life today?

Durability & Green Building Design Service Life Expectations How can we identify service life today? Anecdotal field reports Opinion surveys Historical end-of-service studies Agency approval reports Manufacturer warranty offerings

Durability & Green Building Design Service Life Estimates for Low-Slope Roofing Systems (Years) Opinion Survey N/A No Data System Type Asphalt BUR SBS Modified PVC EPDM TPO Historical Study N/A – 18.4 No Data Agency Report Warranty Offering Data Source 1 Mean service life from Cash (1997), based on an opinion survey of industry participants. 2 Data from the Cash & Schneider studies involved discontinued formulations of PVC that do not allow the data to be meaningful. 3 Mean service life from Schneider & Keenan (1997), based on end-of-service field reports. 4 Estimated service life from British Board of Agrément Technical Approvals (BBA, 2008): 5 Published warranty offerings from NRCA Low Slope Roofing Materials Guide, , Vol. 2, Section 5 Roof Membrane Warranties.

Durability & Green Building Design Service Life Estimates Different Estimates – Different Assumptions: Time Assumptions –Backward looking –Forward looking Quality Assumptions –Uncontrolled sample: Assuming the worst –Controlled sample: Assuming the best

Durability & Green Building Design Service Life Assumptions: Going Forward Time Assumptions: Roofs perform in the future, not the past … … but the future is never certain. Quality Assumptions: Assuming the best may be overly optimistic … … but assuming the worst understates the value of good design, installation and maintenance. Mixed Assumptions: Only increase marketplace confusion.

Durability & Green Building Design Incorporating Service Life Expectations Durability Planning

Durability & Green Building Design Durability Planning Emphasis on Process –A management system –Similar to ISO 9000 & ISO Emphasis on Shared Responsibility –Identifies stakeholders –Identifies roles

Durability & Green Building Design Durability Planning and Canadian Standard S Three Basic Steps: 1.Identify Durability Determinants 2.Identify Durability Interventions 3.Develop Action Plan & Timetable

Durability & Green Building Design Durability Planning 1. Identify Durability Determinants: Provide the Required Functions In the Service Environment By Key System Element

Durability & Green Building Design Durability Planning 2. Identify Durability Countermeasures: During Design During Material Selection During Application & Commissioning During Service Life At End of Service

Durability & Green Building Design Durability Planning 3. Develop Action Plan & Timetable Periodic & Ongoing At Specified Times

Durability & Green Building Design Durability Planning A Suggested Durability Planning Matrix (See Appendix A)

The Service Environment Required Functions Roof System Elements Durability & Green Building Design Durability Planning Matrix

The Service Environment Required Functions Roof System Elements Design Criteria Material Criteria Application Criteria Commissioning Criteria Durability & Green Building Design Durability Planning Matrix (cont.)

Operating / Maintenance Criteria Ongoing & Periodic At X Years At X+ Years At End of Service Durability & Green Building Design Durability Planning Matrix (cont.)

Establish and an Up-To-Date and Active Industry Research Agenda Increase Research Activity, Emphasizing Key Roofing Components & Details Re-Invigorate Consensus Standards Activity with New Research & New Commitment Start Incorporating Durability Planning in Roofing Specifications Continue to Advocate the Importance of Roof Durability Durability & Green Building Design Recommendations Going Forward

SUSTAINABLE BUILDINGS: ADDRESSING LONG-TERM BUILDING ENVELOPE DURABILITY Dr. James L. Hoff Center for Environmental Innovation in Roofing / TEGNOS Research, Inc.