THERESE STOVALL is a senior research engineer in the Building Technology Group at Oak Ridge National Laboratory. Her projects have recently included an assessment of building retrofit options and laboratory evaluations of a variety of insulation materials. She received a BSME from Purdue University in 1977 and an MSME from the University of Tennessee in 1987.
ANDRE DESJARLAIS is a group leader in the Building Technology Group at Oak Ridge National Laboratory and present chairman of Committee C16. He has been involved in building envelope and materials research for over 30 years, first as a consultant and, for the last 14 years, at ORNL. His areas of expertise include building envelope and material energy efficiency, moisture control, and durability.
Committee C16 on Thermal Insulation Contributes to Sustainable Design
Sustainability is not a new concept. In 1789 Thomas Jefferson said, “Then I say the earth belongs to each ... generation during its course, fully and in its own right, no generation can contract debts greater than may be paid during the course of its own existence.”1 (Thomas Jefferson reportedly used an early form of cellulose insulation in Monticello.)
Modern interpretations of sustainability typically focus on making the best possible use of our resources, minimizing our overall impact on the environment, and on developing durable and healthy buildings. Several organizations have produced guides and rating systems to “measure” sustainability, including Leadership in Energy and Environmental Design, the Minnesota Sustainable Design Guide, the Model Green Home Building guidelines, and the Green Building Initiative.2-5 Although these rating systems vary in complexity and cost, they share a common focus on land use, recycled material content, energy conservation features, community planning and quality of life.
Committee C16 makes its major contribution to sustainability by reducing building and process energy consumption and by improving the quality of the indoor environment. Some of the products and processes within the purview of C16 also improve the sustainability of components by including recycled content and improving the ability of a product to be recycled after a building is demolished.
Committee C16 and Sustainability
The ASTM Thermal Insulation Committee was formed in 1938 as manufacturers and researchers struggled to find an accurate way to measure the thermal conductivity of insulating materials. The first ASTM Symposium on Thermal Insulating Materials was held in 1939. In his preface to the Proceedings for the First Thermal Conductivity Conference, hosted by the Battelle Memorial Institute in Columbus, Ohio in 1961, C. F. Lucks tied the increased interest and activity of the 1930s to the “advent of the mechanical refrigerator.” The need for thermal insulation characterization is even more important today, as designers work to balance the future energy savings attributable to insulation, as well as the future health and comfort of building occupants, against the initial resource investment. This resource investment is not only an economic decision, but also affects the amount of space, the amount of raw material, and the amount of construction waste associated with each building element.
Selecting the optimal amount of insulation for any building or process application requires accurate information about the performance of insulation systems with regard to thermal, structural, durability, and moisture parameters. Committee C16 fosters such use through the promulgation of standards that enable system designers to select insulation materials that will provide the necessary service over a range of environmental conditions. Included within its array of standards are documents pertaining to cryogenic applications, building applications, and other commercial and industrial usages. By providing accurate information to the competitive market, material and system standards often lead to product improvements. Furthermore, the development of standards will often speed the market acceptance of new and improved products by reducing the risk and uncertainty inherent in any new product.
Committee C16 provides energy conservation guidance via two main pathways. First, for each insulation product type, material specifications are provided that are based upon recognized and agreed-upon performance measurements. Currently, the committee has more than 40 active material or system specifications along with a number of application guides. Second, the development and use of appropriate test methods and conditions ensure that the material ratings accurately reflect the material and system performance and that test conditions reflect the likely range of use conditions. There are more than 50 active test methods and practices, about half of which address thermal performance or energy transport measurements. All of these standard specifications and test methods are constantly under review and development to meet changing market needs.
The total impact of the C16 standards on sustainable design is broad. Here are a few specific examples of the contributions the thermal insulation standards have made to energy conservation goals.
• Polyurethane foam insulation used in refrigerators and freezers was once manufactured with blowing agents that provided high thermal resistance, but were also high in their ozone depletion potential. After the Montreal Protocol was passed to limit, and eventually eliminate, the use of these gases, the appliance and foam insulation industries worked with the U.S. government to find functional alternatives. Several potential blowing agent gases were identified, but because the foam aging process is relatively slow, it would have taken years to find out which candidate would provide the best life cycle performance. A test method, formalized in ASTM C 1303, was used to accelerate this aging process and give the industry participants the more timely information needed to establish production plants and processes.6
• Most of the sustainable design guides in use describe improved building design for the commercial, institutional, and residential sectors. The sustainable approach is also applicable to industrial processes. Vast quantities of energy are lost each year due to less than adequate industrial pipe insulation. One detailed assessment of energy conservation opportunities in three major industries found that insulating steam pipes could save more than 50 trillion Btu (50 TJ) per year.7 That estimate covers only three industries, only those installations that were judged to be an economic investment based on 2002 fuel costs, and only steam systems. When you expand the scope to other hot and cold process piping and to other industries, the amount of energy conservation potential will be much greater. Committee C16 promotes industrial energy conservation through pipe insulation test methods, installation guides, material specifications, and practices for proper jacketing and coating.
• It has long been recognized that the performance of an individual building component, no matter how well understood, is often insufficient to predict the performance of an installed system composed of multiple components. For that reason, C 16 has developed:
• A test method for a hot box apparatus that encloses an entire system (e.g., a wall, roof or floor) within a laboratory device,
• In-situ test methods for examining heat flux and other variables for an installed building system exposed to the outdoor environment,
• A practice for analyzing such in-situ data, and
• Practices for using thermographic imaging to locate wet insulation or to evaluate the quality of the installation of wall cavity insulation.
• When the first energy crisis occurred in the 1970s, consumers started to install much thicker insulation in their attics. This led to the consideration of two consumer protection issues within the C16 community. First, prior to that time, it was common practice to provide insulation thermal resistance values for a 1-in. (25 mm) thick specimen. For some insulation types, that value does not properly reflect the performance of much thicker applications. Standard practice C 687, Practice for Determination of Thermal Resistance of Loose-Fill Building Insulation, among others, was modified to require the use of a “representative thickness,” that is, a minimum thickness beyond which the thermal resistance per unit thickness is relatively unaffected by the addition of more insulation. Researchers also noticed that natural convection could occur within some insulation materials under certain environmental conditions, depending upon the temperature difference and the insulation thickness. Practice C 1373, Practice for Determination of Thermal Resistance of Attic Insulation Systems Under Simulated Winter Conditions, was developed to transform these research results into a useable tool for industry to evaluate their products under such simulated winter conditions.
• Similarly, researchers found important interrelationships between attic insulation, radiant barriers, and attic ductwork. These heat transfer phenomena were especially important in determining the air-conditioning load on a residential building. Practice C1340, Practice for Estimation of Heat Gain or Loss Through Ceilings Under Attics Containing Radiant Barriers by Use of a Computer Program, was written to help industry evaluate their product performance under this complex situation.
• Windows are a substantial contributor to energy consumption within the building envelope. As the need for a more accurate means of measuring the energy loss through fenestration became critical, Committee C16 teamed with ASTM Committee E06 on Performance of Buildings to develop test method C 1199, Test Method for Measuring the Steady-State Thermal Transmittance of Fenestration Systems Using Hot Box Methods, to address this need.
• As new materials are developed, C16 provides the evaluation and material specifications needed to effectively transfer research into the built environment:
• New standards for rigid cellular polyimide and cellular polypropylene have been added within the last three years.
• As “cool roofs,” or roofs that reflect a substantial percentage of solar radiation, have captured the interest of lawmakers in California and other municipal jurisdictions, Committee C16 has developed the baseline test methods to determine if roofing materials are highly reflective (C 1549, Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer) and emissive (C 1371, Test Method for Determination of Emittance of Materials Near Room Temperature Using Portable Emissometers).
• Vacuum insulation panels provide exceptionally high thermal resistance for confined space applications. Responding to the development of new products, a new material standard, C 1484, Specification for Vacuum Insulation Panels, was developed, as were new test methods.
• New classes of insulation, with improved physical properties, are added to the appropriate material specifications on a regular basis.
What are some of the future plans for Committee C16 with respect to sustainability? One important strategy is to continue cooperating with other standards organizations to leverage the impact of the ASTM knowledge base. The American Society of Heating, Refrigeration and Air Conditioning Engineers is developing a standard that will require the use of detailed moisture management models to all new building designs. Such models require extensive material property data, not available for all building materials of interest. To address this need, Committee C16 has expedited the development of moisture-property related test methods and instituted a task group charged with assembling a comprehensive list of material properties and associated test methods needed to meet the needs of such hygrothermal models.
Cooperation is also continuing with the goal of harmonizing the thermal insulation standards with the International Organization for Standardization (ISO) and the Standards Council of Canada. Other efforts are under way to use mandatory language wherever possible to increase the usefulness of C16 standards to code bodies. In the coming years, Committee C16 will continue to provide the building and commercial arenas with valuable products so that their new designs will contribute to reducing our addiction to fossil fuels, and improve the sustainability of our built environment. //
1 As quoted in Alex Wilson, ed., Greening Federal Facilities, 2nd Edition, http://www1.eere.energy.gov/femp/pdfs/29267.pdf, May 2001
2 U.S. Green building Council, Leadership in Energy and Environmental Design, Washington D.C., http://www.usgbc.org, 2007
3 The State of Minnesota Sustainable Building Guidelines, Version 2.0, www.msbg.umn.edu, Sept. 1, 2006
4 NAHB, Model Green Home Building Guidelines, Version 1, NAHB, Washington, D.C., www.nahb.org/gbg
5 Green Building InitiativeTM, 2004, Green Globes, The Green Building Initiative, Portland OR, www.thegbi.com, 2007
6 K. E. Wilkes, et al, Aging of Polyurethane Foam Insulation in Simulated Refrigerator Panels Four-Year Results with Third-Generation Blowing Agents, Earth Technologies Forum, Washington, DC, April 22-24, 2003
7 Resource Dynamics Corp., Steam System Opportunity Assessment for the Pulp and Paper, Chemical Manufacturing, and Petroleum Refining Industries, U.S. Department of Energy, October 2002