Cross-linked polyethylene (PEX) is a type of plastic composed of individual molecules that have been permanently linked together, creating a very durable and safe material for potable water applications. Cross-linking technology has existed in Europe for over 30 years, but it wasn’t introduced in North America until 1984. Since then, PEX has proven to be a successful alternative to traditional types of plumbing systems, such as copper and CPVC.
The growing popularity of PEX plumbing systems is certainly due in part to its “green” potential. In recent years, there’s been a surge in the U.S. toward products and materials that offer green advantages. For homebuilders, capitalizing on the green trend is one way to gain a competitive advantage in today’s tough marketplace. Early adopters of green technologies can, for example, rebrand themselves as companies offering a higher quality of life to homebuyers. They can also increase their new home market share by capturing buyers who may once have only considered resale. Here, we’re going to look in more detail at how PEX is green in the following categories: durability, water conservation, energy efficiency, and health and safety.
For more than 30 years, PEX has undergone extensive testing and material performance, making it one of the most heavily tested piping materials in the world. Based on these tests, it has proven to be an extremely durable material.
PEX doesn’t experience corrosion, mineral build-up, abrasion, filming, pitting, and electrolysis, issues that are typically associated with metal piping.
PEX is resistant to freeze damage, because it expands and contracts as water freezes and thaws inside the tubing, avoiding costly ruptures.
PEX has the potential for fewer connections, reducing the chance of experiencing leaks, which typically occur at the connections within a plumbing system. With a properly installed home-run
system, there are no connections hidden within the walls, so any leaks that may occur are easy to spot before they cause significant damage.
PEX home-run systems have the potential to conserve water if they’re designed and installed properly. They help conserve water by reducing the amount of time it takes for hot water to arrive at a fixture. As a result, homeowners don’t have to run the water as long while waiting for it to warm up. According to a test conducted by the NAHB Research Center, home-run systems save 30% to 40% more water and time over their trunk-and-branch and remote manifold cousins.
- With a home-run system design, there are direct lines between the hot water manifold and individual fixtures. This reduces the amount of water that must be purged from a line before hot water will arrive at the fixture. Placing the manifold in a central location in the home can further reduce the length of lines.
- With a home-run system design, direct lines can be sized according to the requirements of each fixture. Manufacturers recommend the use of 3/8” tubing whenever possible, which is the smallest diameter available for PEX; a smaller diameter reduces the amount of time it takes for hot water to arrive at a fixture.
To read more about the test conducted by the NAHB Research Center, check out the Toolbase TechNote Cross-Linked Polyethylene PEX in Residential Plumbing Systems.
PEX plumbing systems have the potential to save energy, which translates to a lower energy bill for homeowners.
PEX decreases the amount of energy used by the water heater, because hot water arrives at fixtures faster. This is particularly true of home-run system designs that have the hot water manifold in a central location.
PEX has a higher R-value than other materials, which reduces the amount of heat lost from the water as it travels through the piping. Hot water stays hot, and cold water stays cold.
PEX has fewer connections than other types of plumbing systems due to its flexible nature. This is particularly true of the home-run and remote manifold system designs. Connections add to the effective length of piping, increasing the time it takes for hot water to reach fixtures.
PEX has mechanical fittings, rather than fittings that require the use of propane torches, helping to conserve energy on the jobsite.
Health and safety
PEX plumbing systems are great for transporting potable water, as PEX is an inert, non-toxic material that doesn’t contaminate the water passing through it. It also offers the following benefits.
PEX is manufactured according to the strict standards of ASTM and CSA International. It’s also regularly tested and certified by national certification agencies like NSF International and Underwriters Laboratories. PEX complies with the NSF/ANSI Standard 61 for drinking water health effects.
PEX has mechanical fittings, which don’t require solvents or chemicals that might leach into the water when the system is first used.
PEX doesn’t experience corrosion or mineral build-up, which can occur with other types of plumbing systems.
PEX doesn’t require flame, solder, or flux to install it, resulting in zero volatile organic compound (VOC) emissions.
The European letter system is now commonly used to identify one of three cross-linking methods: PEX-A, PEX-B, and PEX-C. Of these methods, PEX-C excels in the health and safety category. PEX-C undergoes electron beam processing, which results in a clean, chemical-free, and consistently cross-linked material. Learn more about these classifications in the “Cross-linked polyethylene” entry on Wikipedia.
When designed and installed properly, PEX plumbing systems definitely offer green benefits to homebuilders and homeowners. As the trend toward greener products and materials is unlikely to slow anytime soon, now is a good time to begin considering greener technologies like PEX.