benefit performance-based standards in support objective-based codes nrcc47357

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The Benefit of intended-use (performance-based)

standards in support of objective-based codes

Di Lenardo, B.; Ccire, L.; Poirier, G.; Waters, R.

NRCC-47357

A version of this document is published in / Une version de ce document se trouve dan

CIB 2004 Conference Proceedings, Toronto, Ontario, May 1-7, 2004, pp. 1-6

http://irc.nrc-cnrc.gc.ca/ircpubs
http://irc.nrc-cnrc.gc.ca/ircpubshttp://irc.nrc-cnrc.gc.ca/ircpubs


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The Benefit of Intended-Use (Performance-Based) Standards in Support of Objective-Based Codes

CIB 2004 ConferenceT5S4 Performance Based Codes and Standards

Bruno Di Lenardo, Luc Cecire, Gilles Poirier, Ron Waters

Abstract

In many countries a move towards performance-based codes has already begun with varying degrees ofsuccess. In Canada, the move is currently underway towards objective-based codes where theobjectives are articulated around the acceptable solutions. In dealing with innovation as an alternatesolution there will remain a complexity for verifying compliance. To compliment objective-based codes,the standards community could undertake the development of performance-based standards for anexplicit intended use which could be universal and apply to innovation as an alternate solution.

This paper explores the benefits and complexity involved for developing performance-based standards forthe intended use of a construction material or system. These standards would be universal and assist inproduct/system compliance verification for innovation meeting the code objectives. The paper presents a

case study of Canadian insulation industry that is primed for the development of performance-basedstandards for their industry.

INTRODUCTION

In Canada, the building regulatory system is moving towards the use of an Objective-Based Code (OBC).A national public review process has been completed and the OBC should be published in 2005 andadopted into regulation by the Provinces shortly afterwards. After adoption many building officials maysee very little impact on their current task of code compliance verification. The current building codes,with technical updates, continue to be the requirements which are considered acceptable solutionsmeeting the objectives of the codes. In dealing with new and innovative products as an alternatesolution in the objective-based code, the objectives, the sub-objectives and functional statements willprovide more guidance than currently exists in assessing the compliance of innovation.

Bergeron et al1explains that alternate solutions within an objective-based code format will be assessed

based on first principles against the objectives and performance requirements outlined in the OBC. Forthe acceptable level of performance the current acceptable solutions can be used as a benchmark forthe same function or intended use. In Canada, the Canadian Construction Materials Centre (CCMC), thecountrys national construction evaluation service, conducts the majority of evaluations of innovativeproducts that building officials often rely upon for their compliance verification. The CCMC, since itsinception in 1988, has been producing Technical Guides that outline performance-based protocols andcriteria to be met by the innovation to meet the intent of the current National Building Code of Canada.The CCMC, in many cases, has essentially been developing testing protocols based on first principlesand establishing acceptance criteria based on current code benchmarks, very much in line with theanticipated objective-based code process. However, much more explicit guidance will now be availablewith published objectives, sub-objectives and functional statements relating to the requirements contained

in the OBC.

Authors NoteBruno Di Lenardo, P. Eng., is currently an Evaluation Officer with the Canadian Construction MaterialsCentre (CCMC), Institute for Research in Construction (IRC), National Research Council of Canada(NRC), Ottawa, Canada.Luc Cecire, P. Eng., is currently an Evaluation Officer with the CCMC, IRC, NRC, Ottawa, Canada.Gilles Poirier, P. Eng., is currently an Evaluation Officer with the CCMC, IRC, NRC, Ottawa, Canada.Ron Waters, P. Eng., is currently an Evaluation Officer with the CCMC, IRC, NRC, Ottawa, Canada.


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CCMC Technical Guides have been developed for products on a case-by-case basis based on individualproduct submissions. In developing these Technical Guides the CCMC has collaborated with expertsfrom many technical fields and disciplines to develop an evaluation approach and criteria to assessproduct performance. Based on this experience and interaction with industry and the researchcommunity over the years, there exists adequate knowledge to develop universal performance-basedprotocols and criteria for entire classes of products and systems for specific intended uses. Theseperformance-based approaches could be incorporated into standards to assist industry and tocompliment the objective-based code.

Standards Development Intended-Use Performance Standards

Most product standards are currently prescriptive in nature and are dedicated to a specific material,which is represented by a specific manufacturing industry. An example is in top row shown in Figure 1below representing the Canadian insulation industry and the Canadian respective insulation materials.There standards are entirely insulation material specific. It is acknowledged, that although the currentinsulation standards may be prescriptive some specified material properties are indirectly linked to somehistorically known underlying acceptable field performance. Unfortunately over the years the paper trailand knowledge-base has not been maintained on the underlying link to performance. This has resulted inmany product standards being considered by many to be no more that product specifications.

In Canada there is a rapidly changing insulation industry, with new industry players in the marketplace,and ever changing member participation on standard committees. Because standards have an unclearlink to performance, there is confusion within some standard committee members surrounding theprescribed physical properties, the accelerated aging protocols, the test conditions specified and theassigned criteria. There is added confusion when manufacturers attempt to expand the standard toqualify for other intended uses within the building envelope. For example, an insulation attempting toqualify for air leakage control, in addition to providing thermal resistance could result in the individualinsulation material standards going off in different directions. Industrys attempt to include more than oneintended-use within the same standard invariably leads to confusion within committee discussions withrespect to properties and criteria important to one or both intended uses. This situation needs to berationalized to become more productive and efficient if we are to deal with a compendium of technicalissues and set in motion, and maintain, the link with the objectives of the OBC.

One suggestion is to allow for two distinct streams of standards development. One stream would apply tofor the current crop of product standards that are material-specific and a second stream would apply toperformance-based standards that would be intended-use specific as shown in Figure 1 below. Many ofthe benefits of performance-based standards are similar to the benefits of the objective-based codeformat

2, namely:

greater flexibility in application

improved clarity of requirements

greater ease of use

reduced need for change

more responsive to innovation, and

greater clarity of intent and consistency in scope


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FIGURE 1. Two Standards Development StreamsCurrent Material Standards & Intended Use (New).

With the current stream of insulation material standards, the respective insulation industry would continue

to set the grade for the material properties and quality of material they agree to release into themarketplace. This scenario exists now and would be business-as-usual as the second performance-based stream is developed and these new intended-use standards put in place. The second streamwould involve the creation of standards committees that would focus only on the performance for theintended-use giving consideration to the environmental effects of that intended performance for thespecific application. The fundamental performance of insulation is to provide the anticipated thermalresistance for the anticipated service life of the building. The second stream committees would considerthe service life the insulation would be subjected to in terms of the environmental conditions (i.e.temperature cycles, condensation & drying cycles, etc.) within the building envelope.

For instance, insulation materials intended for above-grade walls would be subjected to temperature andhumidity cycles as well as condensation-and-drying cycles. For roof applications, the summertemperatures would be higher so higher temperatures would be in the conditioning protocol beforethermal resistance values are assessed. Insulations which are subject to high-temperature degradationwould be appropriately de-rated or possibly disqualified for use in roof applications. For below-gradeapplications, with moisture present and soil pressure to resist, the performance protocol would addressconditioning to simulate these effects before the thermal performance is assessed. The committeemembers would have to agree on the conditioning parameters, the length of conditioning time, etc. Muchwould be regional climate dependent and various grades or qualification classes could be established forthe regulators to choose the level of performance being sought in their jurisdiction.

Once the second stream is established it will benefit both innovative insulations and current acceptablesolutions insulation materials that would like to qualify for another intended-use. New and innovativeinsulations such as Open-Cell Foams (OCFs), shown in Figure 1, do not have a current product standardbut one is under development. The innovative OCF insulations could initially qualify as a suitable wallinsulation to obtain entry into the marketplace until the industry product standard is completed. Someinsulations may qualify for above-grade-walls and roofs only, such as many fibrous insulations, and will

be designated for walls and roofs only. Other insulations, such as foam plastics, may qualify for allintended uses for walls, roofs and below-grade. In addition, insulation systems that can also be used forair leakage control (i.e. designated air barrier system within the building envelope) within a certain systemdesign, could attempt to qualify to a performance-based air barrier system standard. Similarly, aninsulation acting as a vapor barrier for vapour diffusion control, could qualify as the vapour barrier for thebuilding envelope in meeting a performance-based vapour barrier standard.

Certain insulations, by meeting the respective performance standard, could qualify for use in providing allthree functions of thermal resistance (i.e. condensation control), air leakage control and vapour diffusion


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control. The proposed performance-based stream for intended-use in the building is an excellent way toqualify the minimum expected performance for any material/system. The requirements would be genericand universally applicable to all materials and would go along way in helping industry understand theexpectations of product/system performance.

In Canada, some discussion has begun for the development of intended-use insulation standards. TheCanadian insulation industry engaged a consultant

3to compile and rationalize the relevant properties of

all insulations for various applications. Table 2 below illustrates the results of this study. This table is forinsulations for above-grade wall insulations based on location of the built element within the wallassembly as listed in the first column. The upper row lists the material characteristics or performanceattributes that need to be addressed.

TABLE 2. Compendium of Above-grade Insulation Types and Properties.

For each type of insulation material & location some of the performance attributes were judged lessimportant or not relevant and were discounted by the consultant. However, some fundamentalperformance characteristics are expected of most insulations, such as: thermal resistance, thermaloxidation, thermal degradation, rodent/insect resistance, moisture absorption and dimensional stability.This could be considered a good starting point for establishing a performance-based protocol and criteriathat applies to all insulations while other material-specific attributes may be more suited to remain withinthe industry material insulation standard. The challenge for the scientific community and industry is to

devise a universal test procedure capturing these six fundamental properties that are applicable to allinsulation product types (i.e. boards, batts, loose-fill, spray insulation). While this universal protocol isachievable, a motivated driving force is lacking to set this development in motion.

Performance and Durability CSA Guideline on Durability in Buildings

If the development of universal intended-use standards are put in motion a crossroad will be reachedwhere a decision is necessary on the expected level of durability or resistance to environmentalconditions within the building envelope. The Canadian Construction Materials Centre (CCMC), along withmany other product assessment or product evaluation bodies across the globe, have had to develop both


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performance-based protocols and criteria and also address the durability issue to meet the intended,although implicit, durability performance within building codes. So there is a plethora of performance-based protocols already in use dealing with the performance and durability of materials. One examplediscussed below is the CCMC Technical Guide for Air Barrier Systems of Exterior Walls of Low-RiseBuildings

4developed in 1995.

This Technical Guide has two sections: the air barrier system qualification protocol and the durabilityassessment. The first section for the air barrier system is completely performance-based and isapplicable to any material/system that seeks to qualify as an air barrier system. This first section couldbecome the first section of performance-based standard for the second stream of performance-basedstandards for intended use proposed above. The second section in assessing the durability of the airbarrier system reverts to a durability of the component material in a prescriptive manner rather than auniversal performance-based approach to addressing durability of the air barrier system. There weremany reasons for this including: 1) many accelerated aging standardized test methods are intended forsmall-scale specimens as opposed to full-scale specimens, 2) industry did not appear ready to accept adeparture from the current approach of material tests specified within their respective industry standardsand 3) potentially prohibitive qualification costs if the technical guide deviated from current acceptedsmall-scale prescriptive approaches.

That was the situation in 1995, however, since then there have been many changes in the mindset of

many industry players. Many see the value in performance-based full-scale testing and thedurability/degradation assessment of the full-scale specimen before-and-after aging. When theperformance-based protocol and criteria are representative of the field situation, manufacturers realizethe benefit of the products successful testing in providing an assurance that their product will perform inthe field. Conversely, manufacturers also see the benefit if they discover that their products do not dowell, demonstrating a product they may not want to introduce in the marketplace without furtherimprovements. With the current knowledge in degradation mechanisms of materials and increasingavailability of full-scale test equipment with environmental chambers the time is right for developinguniversal performance-based protocols and criteria for many building materials. To facilitate this task thecommittee can take advantage of the CSA S478-1995 standard, Guideline on Durability in Buildings.

The CSA S478-1995 standard is a comprehensive document intended to guide designers and buildingowner/user on how they can address the durability/service life expectations of all building components.

The document outlines the various degradation mechanisms that can adversely affect all aspects of abuilding and on an item-by-item basis the owner can verbalize his expectations and the designer can thenbegin the selection of appropriate materials and designs to meet the expectations. This CSA Guidelinecould be used for the durability portion for each intended use standard in performance based terms.

Acceptance Criteria Setting

To facilitate the decision maker with selection of the grade of product that would most suit their respectiveneeds, the performance-based standard committee could establish a multitude of classes, for example 3to 5 classes, of durability levels for which the products may qualify. These classes would provide arelative scale for selecting an acceptable minimum for a jurisdiction or a higher level as specified by adesigner or an owner. The actual performance in the field would always be dependent on the regionalclimate and exposure of the product and the regulator could take this into account by also choosing a

level of redundancy.

CONCLUSIONS

The intent of this paper is to signal that the time is ripe within the construction industry for a discussionand debate on the development of performance-based standards for the intended use in the building.The development of these standards would:

clarify intended requirements and assist manufacturers in developing a better understandingperformance expectations of their products and under what environmental conditions.;


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provide clarity for more focused construction product development and innovation;

provide a universal protocol that would not need to change unless an adjustment to the protocolis warranted;

the clarity provided by an intended-use standard would facilitate discussions between themanufacturing industry and user groups.

Although the examples given above for insulations and air barrier systems appear ready-to-go thereremains some work to be done and decisions to be made. In Canada, this could take a few years todevelop and more years to be incorporated into the OBC. For these benefits of intended-use standardsto be put into practice, someone must lead the discussion and champion the cause on behalf of all theconstruction industry stakeholders which would support and benefit from this initiative.

References1. Bergeron, Denis, Bowen, Bob, Tubbs, Beth, Rackliffe, Tony, Acceptable Solutions, CIB World

Congress, April 2001, Wellington, NZ2. Chauhan, Raman B., The Canadian Approach to Fire Safety-Objective-Based Building Codes for

2001, Proceedings, Pacific Rim Conference of Building Officials and 2nd

International Conference ofPerformance-Based Codes and Fire Safety design Methods. May 3-9, 1998

3. Gerald R. Genge Building Consultants Inc., Study of Thermal Insulation Standards for ResidentialApplications, submitted to The Canadian Coordinating Committee for Thermal Insulation Standardsand Quality, March 1995.

4. IRC Publication, Air Barrier Systems for Walls of Low-Rise Buildings: Performance andAssessment, March 1997.

Bibliography1. Beller, Doug, Risk, Reliability and Performance-Based Codes and Standards, Clark University

Workshop on Use of Risk Concept in Performance Based Building and Fire RegulationDevelopment, 1999.

2. CSA S478-1995, Guideline on Durability in Buildings.3. Bukowski, Richard W., The Role of Standards In a Performance-based Building Regulatory System,

Proceedings, Society of Fire Protection Engineers and American Institute of Architects. September

17-18, 2002, Baltimore, MD, 15-24 pp, 2002 AND Performance-Based Codes and Fire Safety DesignMethods, 4th International Conference. Proceedings. March 20-22, 2002, Melbourne, Australia.

4. Bukowski, Richard W., Hirano, Yossy, Tackcliffe, Tony, Standard Linkages to a Performance-Basedregulatory Framework, NIST Building and Fire Laboratory, USA, Building Research Institute of Japanand The British Board of Agrement, UK.

5. Bergeron, Denis., Role of Acceptable Solutions in Evaluating Innovative Designs.

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