New Research Shows How Plastic Piping Fits into Today’s Green Rating Systems

(As published in PS&D, June 2009)

Without a doubt, green is the buzzword of the new millennium. Many product manufacturers talk about sustainability in an effort to prove that they are good stewards of our environment. The challenge for consumers is to identify which product claims relative to sustainability are valid and which are pure hype.

In the construction industry, some organizations help consumers measure sustainability using rating systems that provide points or credits for those projects determined to meet certain standards. With so many certification and environmental programs available, even these helpful messages become blurred. This makes it increasingly difficult for decision makers to confidently pursue environmentally friendly alternatives.

TOOLS TO EASE THE CONFUSION
The life-cycle assessment (LCA) has emerged as a credible, data-driven approach to assessing a product’s true environmental value. It is a comprehensive examination of a product’s potential environmental and economic impact throughout its lifetime, including raw material extraction, transportation, manufacturing, use, and disposal. An LCA is used in many applications, including the building industry, because its scope is comprehensive and it is globally recognized by governmental and certification agencies. (See the sidebar “What Is an LCA?” for additional information.)

A life-cycle inventory (LCI)—which is the data-collection and data-handling phase of an LCA—is a proven tool that examines inputs and outputs in the life cycle of a product to assess environmental burdens. While an LCI does not analyze these inputs and outputs to the degree that an LCA would, it provides a first step to understanding environmental impact. The LCI enables a comparison of energy consumption and environmental emissions among materials, including waste and global warming potential, which is driven by greenhouse gas generation.

Recently, Franklin Associates, a third-party research team and member of the Eastern Research Group, performed an LCI study for the Plastic Pipe and Fittings Association (PPFA) to examine the environmental burdens of CPVC, PEX, and various types of copper piping systems. This in-depth LCI study supports the use of plastic piping in green construction projects because of their favorable environmental burden and global warming potential results.

HOW WAS THE LCI CONDUCTED?
Franklin Associates compared data for 1,000 lineal feet of pressurized, ¾-inch CTS (copper tube size) hot and cold water distribution (HCWD) piping made from a variety of plastics and metals. For purposes of the study, ¾-inch pipe was selected to represent an intermediate size of pipe commonly used for both residential and commercial projects where the majority of the pipe used is ½-inch to 1-inch pipe. The study included analysis of various types of copper piping, including K, L, and M, to cover a variety of applications where plumbing pipe would be installed, including both above- and below-grade applications and geographic locations where more aggressive water conditions are common.

The LCI focused on energy, solid wastes, and chemical emissions in terms of global warming potential. The analysis included all processing stages from raw material extraction through pipe fabrication, as well as the transportation of materials from the manufacturer to the customer. The manufacture and disposal of transportation packaging also were included. While the LCI phase of an LCA focuses on raw materials through production, the materials and impacts involved during installation are studied in the second phase of the LCA.

Evaluating Energy Efficiency
The LCI presents the energy used to produce 1,000 equivalent feet of each kind of pipe studied. That energy calculation is broken down into three categories of energy usage: process energy, transportation energy, and energy of material resource.

Process energy includes energy for all production processes, from raw material acquisition through pipe manufacturing. For this study, copper is assumed to consist of two-thirds scrap copper and one-third stripped from the land in a mining operation. A benefit is that recycled copper takes less energy to process than virgin material. Transportation energy includes the energy needed to move material from location to location as it is taken from raw material to finished product. Energy of material resource (EMR) is the energy value of the piping and packaging materials. For plastic piping, this includes the plastic resins and packaging materials, which are derived mainly from petroleum or natural gas. Copper, by contrast, has no energy value itself, so its EMR is virtually zero. It is the combination of these three energy components that defines the total energy for each type of pipe.

However, despite the low EMR, as Figure 1 illustrates, the energy requirements for copper are still considerably greater than those for either CPVC or PEX pipe, even after factoring in high copper recycled content. That’s largely due to the fact that copper requires an energy-intensive mining process. Plastic requires far less process energy to melt and shape into pipe dimensions, with CPVC requiring even less total energy than PEX. Since CPVC is roughly one-sixth the weight of copper, less fossil fuel energy is required to transport the piping from the manufacturing site to the jobsite.

THE IMPACT OF SOLID WASTE
The solid waste category of the LCI examines how much of a product enters the waste stream and how much can be recovered or recycled at the end of its service life. In this context, solid waste is divided into three categories: process wastes, fuel-related wastes, and post-consumer wastes.

Process wastes are generated by the various processes from raw material acquisition through material manufacture. Fuel-related wastes are those that result from the production and combustion of fuels used for process energy and transportation energy. Postconsumer wastes include the pipe packaging wastes and pipe that is disposed of at the end of its service life.

The LCI shows that copper pipe is responsible for less solid waste than plastic pipe because copper often does not end up in landfills due to its high recycle value (see Figure 2). When copper or plastic pipe is recycled, additional energy must be consumed to process the material for reuse. The energy required during copper recycling is far greater than what is consumed when recycling plastic. However, since most of the plastic pipe installed has not yet reached the end of its service life, a consistent stream of plastic pipe currently is not available for recovery. Recycling and recovery options are expected to increase as the economics of plastic supply and demand become more favorable. PEX pipe can, however, be down-cycled, which means it can be reused for other unrelated applications, such as filler for other thermoplastic building materials. The market for this filler product is just beginning.

When comparing PEX and CPVC relative to solid wastes, it is important to note that PEX is a thermoset, meaning that the material cannot be recycled by melting and reforming it for new uses. However, energy in this type of plastic pipe can be recovered by incineration at a waste-to-energy facility specially designed for this purpose, where a combustion process is used to safely generate steam or electricity. This process provides alternatives to disposal of solid waste and to fossil fuel combustion traditionally used to support the community. CPVC, on the other hand, is a thermoplastic material, meaning it becomes softer when heated and harder when cooled. This property allows it to be recycled and formed into another piping product or into non-pipe applications such as building materials. All thermoplastic products, including vinyl plastics such as CPVC, can be recycled and reprocessed into second-generation products. The Vinyl Institute now offers a directory of recycling companies at www.vinylinstitute.com.

GLOBAL WARMING POTENTIAL
A common way to assess atmospheric emissions produced from combustion is by adding the relative contribution of each greenhouse gas expressed in their carbon dioxide equivalents. These total values, known as global warming potential (GWP), provide a common basis for comparing piping systems.

The Franklin Associates LCI study examines three primary atmospheric emissions that contribute to global warming: fossil fuel-derived carbon dioxide, methane, and nitrous oxide. The majority of GWP for each system studied is from fossil fuel-derived carbon dioxide, followed by methane. In fact, more than 75 percent of total GWP for all pipe systems is from carbon dioxide from the combustion of fossil fuels. Thus, pipe systems that require combustion of large amounts of fossil fuels for process and transportation energy have a higher GWP. Therefore, plastic piping (both CPVC and PEX) contributes significantly less to GWP than any grade of copper (see Figure 3).

BEYOND THE LCI
Although the LCI study conducted by Franklin Associates is, without doubt, a strong comprehensive analysis that provides a factual, data-driven comparison between the environmental burdens of plastic piping to that of copper piping, it is not the first credible environmental assessment of CPVC as a sustainable building material.

Another strong testimonial to the health and environmental benefits of CPVC came from California where extensive analysis was undertaken regarding the product’s environmental impact. This analysis was done before revising the plumbing code in 2007—a change which eventually allowed the unrestricted installation of CPVC plumbing pipe.

Yet another supporting study is from the Technical and Scientific Advisory Committee of the U.S. Green Build Council. While CPVC was not specifically assessed, PVC and CPVC would have yielded similar results for the purposes of this study since they are both vinyls with the same properties and derived from the same raw materials. The report titled Assessment of the Technical Basis for a PVC-Related Materials Credit for LEED, dated February 2007, (available at www.usgbc.org) assessed four PVC-based materials: siding, DWV (drain, waste, and vent), resilient flooring, and window frames.

PVC-based products were compared to their non-PVC counterparts, such as metal pipe, to investigate whether the PVC-based materials were consistently among the worst materials studied in terms of environmental and health impacts. The study identified three different impact categories: environmental/resource (including acidification, ecotoxicity, eutrophication, and fossil fuel depletion); combined human and ecosystem health (including ozone depletion, global warming and photochemical smog); and strictly human health (including particulates, cancer and other).

The report states that, in terms of human health impact, “If buyers switched from PVC to aluminum window frames, to aluminum siding, or to cast iron pipe, it would be worse than using PVC.” In terms of environmental impact, the report states, “The evidence indicates that a credit that rewards avoidance of PVC could steer decision makers toward using materials that are worse on most environmental impacts.” It is clear from this report that the use of PVC-based products can be an environmentally sound choice compared to some alternative products.

It is also important to note that there are no LEED points given or taken away for the type of plumbing pipe used. Plumbing components are specifically excluded from the Material Resource section of the LEED rating system, as are mechanical and electrical components, as well as specialty items, such as elevators.

Furthermore, CPVC has performed for nearly five decades showing that it will not affect water quality and will not corrode in aggressive water like metal pipe. It meets all the requirements of NSF/ANSI Standard 61, which evaluates materials to ensure they do not leach EPA-regulated contaminants in the water that would represent a health concern.

In contrast, copper does not meet these NSF requirements when the water has a pH level under 6.5. For this reason, copper carries a disclaimer with regard to its potable water certification, which excludes it from meeting EPA standards in those areas that do not meet the product’s strict pH requirements. Corrosion also can lead to scale buildup inside the pipe, increasing the friction and requiring more energy to move water throughout the systems. Most important is the fact that corrosion can lead to premature failure. A plumbing system that has to be re-piped or replaced more often than another is clearly not sustainable and represents greater environmental liability than the alternative.

CPVC is not susceptible to corrosion, pitting, or scaling. That translates into fewer water quality concerns and elimination of leaks or premature failures resulting from corrosion. Between the independent reports and nearly 50 years of performance, CPVC continues to earn merit as a sustainable building material.

CONCLUSION
A life cycle inventory provides a very comprehensive, unbiased comparison of common piping materials relative to their environment burden. While a full life cycle analysis provides more complete answers to how a single manufactured product fares in the comparison, the LCI comparison of copper, PEX, and CPVC piping materials shows factual, data-driven results that many product claims lack. In tracking the various materials throughout their entire life cycle—from manufacturing through installation and disposal—CPVC has proven to perform in line with today’s stringent environmental standards. Using the LCI tool and other data-supported resources, building professionals charged with making environmentally responsible decisions can be confident that CPVC provides clear environmental and performance benefits.