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Are there any green issues with PEX?

artisanfarms | Posted in General Questions on

Are there any green building reasons not to use PEX for plumbing?  

On remodelling projects, I have always used copper because the existing plumbing was copper, but my current project includes a complete replacement of the plumbing and I am considering using PEX to save installation time. 

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  1. walta100 | | #1

    Not all PEX is the same and the fitting fit on the inside of the tube instead of the outside. If need/want the same flow rates you are used to with PEX you need to up size the pipe with some or most flavors.

    I will let other discuss whether an oil well is greener than a copper mine


    1. Expert Member
      NICK KEENAN | | #11

      >I will let other discuss whether an oil well is greener than a copper mine

      I find the monetary cost of an object is a good first approximation of the environmental cost of that object.

  2. Expert Member
    BILL WICHERS | | #2

    I don’t see any negative to using PEX, green or otherwise. I suppose if you want to keep things minimalist, you could use the white (natural) colored PEX that doesn’t have dyes in it. Aside from that, you have to use something to carry fluids around, and I don’t see there being any significant difference in greeness between PEX and copper, or PVC for that matter. Don’t believe all the “chemicals” stuff you sometimes here, either, PEX is not like the flexible plastics used in things like squeeze bottles — it’s a totally different material and very much more stable.

    I do recommend the crimp-type PEX connections over the shark bite type. I don’t trust O ring seals over time.


    1. this_page_left_blank | | #9

      Cold expansion PEX (type A) beats crimp PEX by a mile. I've had crimp connections leak before. Type A can also be bent in a tighter radius, and accidental crimps can be repaired with a heat gun, much less constriction at fittings, and doing the expansion in a confined space usually presents fewer challenges than getting a crimper into the space.The only downside is the tool cost, but even for a single house it's worth it.

      I agree that the rubber o-ring connections are just a ticking time bomb.

      1. Expert Member
        MALCOLM TAYLOR | | #10

        I'd find out what types of pex are commonly used where you are building . 99% of houses here in BC are plumbed with crimped pex connections. It doesn't make much sense to use another type here.

  3. tommay | | #3

    How can you figure a chemical composite can be green compared to a "natural" element?

    1. JC72 | | #4

      Because it takes a lot of energy to extract, refine, extrude, and install that "natural" element.

      Being "green" doesn't have to be relegated to the composition of the material.

      OP: My guess is that it's a wash or perhaps PEX comes out ahead simple because it takes more energy to produce, you'll use less product, and you don't have to connect joints with a torch/solder.

      1. tommay | | #5

        Most of today's copper is recycled and has been used over and over again. Try recycling a bunch of plastic and see what comes out of the process.
        As far as joints with solder, you have more connections with pex using more material, usually cheap brass, which needs to be extracted and processed.

        1. Expert Member
          BILL WICHERS | | #6

          You have lots less connections if you use PEX. Copper is 10 foot sticks, and at least one fitting at EVERY change in direction. PEX can be a long run and it can make bends if they’re not too sharp without a fitting. I can’t imagine how you’d do a PEX install and not come out ahead on the number of fittings compared to copper.

          Even recycled copper had to be melted down and reprocessed. It takes a LOT of energy to run those furnaces. Much of the energy that went into the resource extraction process for PEX was doing other things too, probably not solely making PEX.

          If you want to build a structure using exclusively naturally occurring materials, you’re going to be very limited in what you can accomplish. You always need to consider the entire system and not just focus on any one part of it.


          1. tommay | | #7

            A lot of foundries today no longer use furnaces to process product. They use electrical induction. And as far as fittings, when using pex, individual runs are usually used rather than using branches off a main trunk (and they sell 20 footers of copper pipe), so for instance, one tee can supply two fixtures off a trunk line and maybe a couple of 90's, whereas several or more fittings and crimp rings are needed to serve those same two fixtures, especially when you consider you need fittings at the beginning of the run and double the fittings once you get to your final connection where valves are needed especially if you have to transition to copper, and those bends, in some cases, require a special sleeve to maintain and keep the bend from crimping.

          2. this_page_left_blank | | #8

            Tom, you're building a bunch of straw men to support your argument.

            A trunk and branch system can be done with either PEX or copper, just like a home run system. The only reason it's more often done with PEX is that it's a lot less work and a lot cheaper with PEX.

            The energy input for recycled copper is not much different than virgin copper. There's enough of a difference to certainly make it worthwhile, both economically and ecologically, but it's not such a big difference as to be a game changer in terms of comparing it to other materials such as PEX.

            Your assertion that "a lot of foundries no longer use furnaces to process product" is just a red herring, or maybe pie in the sky thinking. The vast majority are still using furnaces, and probably a pretty large chunk of those using induction are using electricity produced by fossil fuels. This type of argument is similar to saying that electricity is green because some generators are using solar, wind and hydro, without acknowledging that most of it still comes from coal and other fossil fuels. If you think I'm wrong, feel free to provide evidence for your claim.

            I don't follow your math on number of fittings. Using tees does nothing to reduce the number of fittings. It reduces the total length of line. No matter how you route it, the minimum number of fittings per devices is two; one to split it off from the main source, and one to terminate it at the device.

            Your example comparison highlights a host of prejudices and blind spots. For example:
            "one tee can supply two fixtures off a trunk line and maybe a couple of 90's" Wait, what? You've only counted one of the two tees (one from the main source, another to split the lines into two), and you've not counted the fittings at the fixture. So that's actually 5 fittings where you assumed three. Then here:
            "whereas several or more fittings and crimp rings are needed to serve those same two fixtures"
            I don't know where you think these several (or more) fittings are. A home run system will have a manifold, then the fittings at the fixture. The end. Where are the several extras? So even if you count the manifold as two, it's still fewer than in the trunk and branch example.

            "especially when you consider you need fittings at the beginning of the run and double the fittings once you get to your final connection where valves are needed especially if you have to transition to copper"
            You mean the same fittings at the beginning and end of the run that you ignore in the copper trunk and branch system? Maybe the issue is what you're considering a fitting, but I've never seen a faucet that accepted a copper line directly without a fitting. Whether you're using PEX or copper, a fitting is used to connect the line to the fixture.

            "those bends, in some cases, require a special sleeve to maintain and keep the bend from crimping"
            The use of those sleeves is uncommon. They can be avoided completely by using type A PEX. I managed to plumb my entire house with PEX and didn't use a single change-of-direction fitting or any bending sleeves, and it took no special effort to do so.

          3. Expert Member
            BILL WICHERS | | #12

            Tom, the electric arc furnaces are primarily working with scrap steel. I’ve worked with some metal reprocessing sites working with aluminum, and they were using natural gas to fire their furnaces. Aluminum doesn’t work as well with arc furnaces due to its conductivity, and I’d assume copper would have similar issues. I’m not aware of anyone using electromagnetic induction to melt metal at this scale (that process is usually used for small things and only to heat the metal, not to melt it completely). Normal Induction won’t work with copper or aluminum, either, due to the properties of the material.

            I’m not at all opposed to using copper, and that’s what’s in my own home (since that’s what the home was originally built with back in the day), but I wouldn’t say PEX doesn’t have some advantages.


          4. bluesolar | | #13

            Bill, are you sure about induction furnaces? My impression is that they're everywhere, used for steel, copper, precious metals, etc. Here's a release about Nucor buying one:

          5. Expert Member
            BILL WICHERS | | #14

            Bluesolar, I looked into this and apparently they are using induction furnaces for materials other than steel these days, which surprised me. Different materials need different operating frequencies for operation, and this used to limit the use of these furnaces more than it does today. Induction furnaces used to be used primarily for heat treating, so they didn’t need to melt a metal, just heat it. Such furnaces were very fast and efficient in this application.

            Large furnaces used to use vacuum tube amplifiers as drivers to create the high power, relatively high frequency (tens or hundreds of kilohertz usually) that they needed for operation. Newer stuff is using IGBTs apparently, which is a variation on a transistor that is easier to drive in high power operation. My guess is this is the big enabler for this technology to work with other materials.

            Note that arc furnaces, which are commonly used with scrap steel recycling, work by heating the material by lowering big carbon rod electrodes into a crucible of the material being melted. These furnaces work by electrical arc (spark) and resistive heating. This is very different from induction heating that works primarily by eddy currents created in the heated material by an oscillating magnetic field. Arc furnaces don’t play nice with the power grid without flicker filters, but are otherwise pretty simple machines. Induction furnaces require much more complex electrical drive systems.

            As far as I know, most of the aluminum processors are using natural gas fired furnaces. I’ve worked with steel and aluminum plants but not copper, so I don’t have personal experience with any copper processors.


          6. tommay | | #15

            Trevor, I'll just comment on one of your statements, " I've never seen a faucet that accepted a copper line directly without a fitting" ...With copper you solder on a valve, which is necessary with either copper or pex, then use a supply to the faucet. A lot of faucets today already have a supply attached. So zero fittings at the faucet. With pex you need to transition so more fittings. ....And you say you plumbed your house.... well, when you've plumbed thousands of houses as I have, then you may have a better understanding. I'd rather run one trunk than multiple homeruns, less time and labor.
            And those saying that induction processing is just as bad, go back and look at all your arguments to going all electric.
            One other benefit of copper and silver solder is that they are antimicrobial.
            Multiple types of plastic tubing systems have come and gone over the years. Only time will tell if pex gets recalled as all these other systems have.

          7. Expert Member
            BILL WICHERS | | #18

            Tom, PEX is crosslinked polyethylene. This same material, or similar variants, has been used as insulation in electrical cables for around 60-70 years. I don’t think we’ll have any surprises with PEX the way some of the other plastic piping systems have.

            Nothing wrong with copper, but it can have issues too. I’ve had to reflow the solder on 50 year old 90s before due to stress cracking after decades of hot/cold thermal cycles on a hot water line. I suspect PEX systems using push fit connectors might have similar small maintenance issues decades down the road too. Everything ages after all.


  4. tommay | | #16

    Blue Solar, right, the main reason is that they can now process as little product as they need, as needed, rather than heating up a large furnace that would have to process a large batch in order to be economically efficient.

  5. walta100 | | #17

    I remember this controversial law passing in hopes of reopening an aluminum plant. The plant may or may not have been a foundry.

    Bill you may find this article interesting

    I am not sure how we got to talking about aluminum.

    Aluminum is extracted from ore by electrolysis in the Hall-Héroult process.
    The Hall-Héroult process uses a huge amount of electricity; hundreds of thousands of amperes.


    1. Expert Member
      BILL WICHERS | | #19

      Hundreds of thousands of amperes at maybe a few volts, so a few hundred kilowatts. Those big aluminum plants are usually the largest users of electricity in their area. That’s per cell though, so with many cells in a typical plant, the plants tend to be multi-megawatt users of electricity.

      There is a massive plant in New Zealand and a nearby hydroelectric plant that was constructed primarily to power the aluminum plant. Is this a bad thing? No, not really. The process itself is to separate the pure aluminum from the bauxite alloy. It’s a very efficient process in terms of what it does. All industrial processes tend to be large consumers of energy, but it’s because they are doing their work at such a massive scale to be efficient. There are relatively few of those large plants supplying all of the worlds aluminum.

      An interesting fact is that aluminum was considered a precious metal just like silver and good before he electrolytic separation process was discovered. Napoleon I think it was had a set of silverware made from aluminum because it was so valuable at the time. Now, aluminum is a cheap metal — much cheaper than copper. It’s my favorite metal to work with for fabricating metal things too. I have a bunch of 6061-T6 extrusions and 5052 sheet I use to make stuff.


  6. nickdefabrizio | | #20

    Here is one downside to Pex and plastic cages on a bathroom fan: Animals....A few weeks ago I went to open up my dad's summer home at the Jersey Shore. When I turned on the water, a flood streamed down into the first floor from above. After ripping out the walls above, we discovered that a squirrel had chewed through the Pex main water line !! It was amazing but it had been clearly eaten clear through. The squirrel had climbed up the mini split line, busted through the plastic cage on the bathroom fan and climbed through the fan vent to somehow get into the area behind the tub where the main water line was (my neighbor watched the squirrel climb in one day). Amazing! I guess the animal was looking for water in its winter nest....

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