{"id":36819,"date":"2017-06-07T10:44:51","date_gmt":"2017-06-07T14:44:51","guid":{"rendered":"https:\/\/www.constructionspecifier.com\/?p=36819"},"modified":"2017-06-08T09:17:31","modified_gmt":"2017-06-08T13:17:31","slug":"at-the-intersection-of-fire-safety-and-energy-efficiency","status":"publish","type":"post","link":"https:\/\/www.constructionspecifier.com\/at-the-intersection-of-fire-safety-and-energy-efficiency\/","title":{"rendered":"At the intersection of fire safety and energy efficiency"},"content":{"rendered":"
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All images courtesy Hunter Panels<\/span><\/em><\/span><\/figcaption><\/figure>\n

by MacGregor Pierce
\n<\/strong>In 2015, The United States experienced 113,500 nonresidential structure fires<\/a> (the latest year for which data on this are available), resulting in 80 civilian deaths and $3.1 billion in property damage. The same year, the country\u2019s commercial buildings consumed approximately $144.8 billion<\/a> in electricity. Building professionals face the multi-faceted challenge of minimizing all these figures for their clients.<\/p>\n

An interesting dynamic in U.S. building codes is the dual requirement for the building envelope to both be energy-efficient and help protect life and property against fire. These two needs intersect clearly in wall-assembly requirements. On one hand, American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE) 90.1, Energy Standard for Buildings Except Low-rise Residential Buildings<\/em>, and the International Energy Conservation Code<\/em> (IECC<\/em>) require continuous insulation (CI); on the other, rigid-foam insulations commonly used to provide CI must also meet fire-safety requirements. Specifically, National Fire Protection Association (NFPA) 285, Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-loadbearing Wall Assemblies Containing Combustible Components<\/em>, requires rigorous testing of foam-plastic insulation within wall assemblies.<\/p>\n

This article focuses on rigid-foam CI options that can simplify meeting NFPA 285 requirements.<\/p>\n

NFPA 285 overview
\n<\/strong>At its core, NFPA 285 is intended to evaluate the performance of combustible materials in wall assemblies required to be noncombustible.<\/p>\n

Scope
\n<\/em>With limited exceptions, International Building Code<\/em> (IBC<\/em>) Section 2603.5.5, \u201cVertical and lateral fire propagation,\u201d requires wall assemblies in Type I, II, III, and IV construction using foam-plastic insulation to pass NFPA 285 testing requirements. Despite the use of \u2018non-loadbearing\u2019 in its title, NFPA 285 applies to both non-loadbearing and loadbearing walls.<\/p>\n

The NFPA 285 official document scope<\/a> states:<\/p>\n

This test provides a method of determining the flammability characteristics of exterior, non-load-bearing wall assemblies\/panels. The test method described is intended to evaluate the inclusion of combustible components within wall assembled\/panels of buildings that are required to be of non-combustible construction. It is intended to simulate the tested wall assemblies\u2019 fire performance.<\/span><\/p>\n

It is important to remember NFPA 285 is an assembly test, not a product-specific test. Although a given component passes the test in one assembly, this does not mean it will be compliant in another. As a result, when designing NFPA 285-compliant wall assemblies, certain combustible components cannot be mixed and matched without engineering evaluation conducted within limits imposed by \u2028the IBC<\/em>.<\/p>\n

The test of the assembly is comprehensive and includes everything from the interior drywall to the exterior cladding, along with the structural elements, insulation, and water and air barriers.<\/p>\n

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Polyisocyanurate (polyiso) products have also been tested to comply with National Fire Protection Association (NFPA) 285, Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Non-loadbearing Wall Assemblies Containing Combustible Components<\/em>, with a range of cladding types.<\/span><\/figcaption><\/figure>\n

Test procedure
\n<\/em>The NFPA 285 test evaluates flame spread\u2014vertically and horizontally\u2014across the wall assembly, along with ensuring temperatures are not exceeded within specific areas.<\/p>\n

The test involves construction of a two-story room, with the proposed wall assembly as the exterior wall. The lower room includes a window opening (non-glazed). To simulate a building fire, \u2028a gas burner is placed in the center of the lower room, and a second, portable gas burner is placed in the window opening. The two burners are ignited at specified intervals during the 30-minute test and must heat the first floor to defined temperatures by specified times.<\/p>\n

Test results
\n<\/em>The test results are expressed as either \u2018pass\u2019 or \u2018fail.\u2019 Either an insulation (or other product) is deemed to be NFPA 285-compliant in a given wall assembly, or it is not. NFPA 285 does not rate using degrees of performance, as is the case with some fire tests (such as those for fire-rated glazing that result in 30-, 60-, or 90-minute ratings).<\/p>\n

To pass NFPA 285, at no time during the test can flames spread beyond defined horizontal and vertical limits outside the building\u20143 m (10 ft) above the top of the window opening and 1.5 m (5 ft) horizontally from the window centerline. Additionally, no flame propagation is allowed into the second-floor room, \u2028and the temperature at five thermocouples placed 3 m \u2028(10 ft) above the window cannot rise to greater than 538 C (1000 F).<\/p>\n

Engineering analysis option
\n<\/em>As NFPA 285 is an assembly test, building product manufacturers generally must test their materials within many different wall assemblies. To avoid the impracticality of testing every possible combination of materials in an assembly, engineering analysis may be permitted in accordance with IBC<\/em> Section 104.11, \u201cAlternative materials, design, and methods of construction and equipment.\u201d Additionally, some code reports\u2014such as those issued by International Code Council Evaluation Service (ICC-ES), applicable across all jurisdictions\u2014specifically allow engineering analysis by independent laboratories to extend the NFPA 285 test results. Such analysis might include cone calorimeter flammability testing to determine if a proposed alternative material performs the same or better than a given NFPA 285-compliant product. (For additional discussion, see \u201cNFPA 285: Engineering Extension of Tested Assemblies\u201d at www.appliedbuildingtech.com\/content\/nfpa-285-engineering-extension-tested-assemblies<\/a>.)<\/p>\n

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NFPA 285 is intended for assemblies, meaning all components of a wall, from interior drywall to structure, insulation, and exterior cladding, are included.<\/span><\/figcaption><\/figure>\n

Using rigid-foam insulation <\/strong>\u2028<\/strong>in NFPA 285-compliant assemblies
\n<\/strong>As rigid-foam insulations are combustible, they \u2028must pass as components within NFPA 285-tested assemblies to be used as CI. The rigid foams commonly used in wall assemblies are:<\/p>\n