PEX or Copper: Which is more sustainable?
By Kim Bliss
With the shift to environmental building design, professionals are now tasked with the challenge of creating a structure that is sustainable, cost-effective and high-performing — which is no easy feat. However, new technologies are offering alternatives to help professionals find that perfect balance of saving green while staying green.
Take PEX piping, for example. PEX is an acronym for crosslinked polyethylene, which is a flexible, durable plastic piping product predominantly used in the plumbing and radiant heating and cooling markets. While it has been used successfully in residential applications for the past 40 years, the use in commercial markets is relatively recent — in the past decade or so.
With PEX now being offered in sizes up to 4 inches, its use in commercial applications, such as plumbing, radiant heating/cooling, hydronic distribution piping and underground pre-insulated piping systems, is gaining popularity. The growing popularity is challenging traditional copper, steel and CPVC materials that have dominated the commercial building industry for the past century. And now, with the focus on sustainable building, questions are arising about which material is best from a sustainability, cost-effectiveness and performance perspective.
The PEX community heard the call, both here in the states as well as overseas. The Plastic Pipe and Fittings Association (PPFA) and The European Plastic Pipe and Fittings Association (TEPPFA), which represent the key manufacturers of plastic pipe systems in North America and Europe, respectively, each commissioned third-party research to find which material is more sustainable over the life of a system — PEX or copper.
The data took into account factors such as exhaustion of natural resources, emissions from manufacturing processes, over-fertilization of water and soil, global warming, ozone layer depletion and photochemical oxidation to formulate the Life Cycle Impact on the environment. The results indicated that the impact of plastic pipe systems on the environment is smaller than that of traditional materials. (Data for traditional materials [concrete, ductile iron and copper] are based on publicly available data.)
Specifically, the report stated that lightweight plastic piping products are expected to have lower environmental impacts during manufacturing compared with copper because lighter-weight products (i.e., PEX) reduce manufacturing, transportation and disposal burdens. The report also found that the energy consumed and overall impacts from manufacturing plastic pipe using common, low-temperature extrusion processes are but a small fraction of the already minimal environmental impacts of plastic pipe. In other words, plastic pipe extrusion processes are clean and low-impact operations.
The process by which copper is mined, refined, transformed into end products and then used — such as pipe — is very energy-intensive, using a great deal of nonrenewable energy during its lifetime. And, copper piping systems can have a much shorter lifespan compared with PEX because of the corrosion and pinhole leaks that can happen with harsh water systems.
PEX pipe, on the other hand, is a much more durable and longer-lasting building product. PEX will not pit, scale or corrode like copper can. And, due to its extreme flexibility, PEX is even highly resistant to damage from frozen water because the pipe can expand up to three times its diameter and then contract back down to its original size.
Additionally, long-term testing programs on PEX have shown that it has a potential lifespan of more than 100 years. So, while copper systems may have to be re-piped every few years or decades due to corrosion and pinhole leaks, a PEX system can last 10 times longer — or more.
Time is on PEX’s side
Some may be questioning, how can a plastic product like PEX that uses a raw material derived from nonrenewable resources, such as natural gas or crude oil, be a good choice for the environment? Consider this: When taking into account all the alternative uses for crude oil and natural gas, it is readily obvious that such "feed stocks" are far better off employed for the manufacture of durable goods (such as pipe) rather than being consumed (i.e., burned up) in single-use applications, such as gasoline or diesel fuel for vehicle engines. Simply put — isn’t it better to use these nonrenewable energy sources to create a product that will last more than 100 years in a structure, rather than being burned up in a couple hours (or minutes) in a vehicle?
And, PEX piping systems — whether for plumbing, hydronic distribution piping, radiant heating and cooling, or fire safety — are all sustainable solutions in their own right. A flexible PEX plumbing system, for example, can bend around corners with each change of direction, instead of having to add a connection. This reduces materials inside a building and can also improve water flow for better performance.
Additionally, PEX’s thicker walls and lower thermal conductivity mean it can help keep hot water hotter longer and also be more resistant to condensation on cold-water lines than a copper system. The slightly smaller internal diameter (ID) of PEX compared with copper means the system will waste less water down the drain while you’re waiting for the hot water to reach the tap.
Hydronic radiant heating and cooling systems that utilize PEX under the floors or in the walls or ceilings to transport warm or cool water to condition an interior space are also highly sustainable systems. Radiant heating and cooling systems are known to increase indoor environmental quality and minimize the need for traditional HVAC systems that require greater energy to operate. Plus, radiant systems work very well with renewable energy sources such as geothermal and solar, making them even more sustainable.
After careful consideration and looking at all the different aspects of a building product, it is easy to see that there are several factors that can contribute to a product’s sustainability performance. Simply looking at one factor can be misleading and can limit one’s options for finding that delicate balance of sustainability, cost-effectiveness and performance when designing and building a structure. l
Kim Bliss is the senior writer of Technical Communications at Uponor, Inc. in Apple Valley, Minn. She can be reached at email@example.com.