AskPablo: Napkins

napkin.jpgThis weeks question is from Nick Gruber: “My question has to do with linen napkins vs. paper napkins. Is it more efficient to use linen napkins (factoring in the energy for picking them up and washing them) or paper napkins (recycled paper napkins)?”

Let’s start with some very basic assumptions to frame this analysis. I am assuming that the paper napkin is made from 100% recycled paper content and that the fabric napkin is made from conventionally grown cotton (it is much easier to find data on cotton than on flax, from which linen is made). The weight of each alternative is also critically important in terms of its material input intensity, but negligible in terms of transportation. The paper napkin is assumed to weigh 5 g and the cotton napkin is assumed to weigh 32 g. The paper napkin is used only once, while the cloth napkin will be reused 50 times over its lifetime.
Recycled paper fiber has a significantly lower material intensity than virgin paper. 1.75 g of CO2 per gram of bleached virgin paper vs. 0.05 g of CO2 per gram of recycled paper. The difference in water use is also impressive, 303 g vs. 15 g. The cotton is even worse than the bleached paper at 2.74 g of CO2 per g and 6814 g of water used per g. (Source: MIPS data tables, Wuppertal Institute)
Based on our assumption and factors stated above the paper napkin results in 0.25 g of CO2 emissions (or 8.75 g for non-recycled paper) and the cotton napkin is responsible for 87.68 g of CO2 emissions.
In terms of water used during the manufacturing of both napkins we get 75 g of water for the recycled paper napkin (or 1515 g for non-recycled paper) and the cotton napkin is responsible for 218,048 g of water use (that’s 218 liters!).
The results for the cotton napkin are higher not only because of its higher water and carbon emissions factors but also because it weighs more. But we are not simply comparing napkins here, we are comparing lip wiping and hand cleaning services. Therefore we need to compare the cloth napkin with a comparable amount of paper napkins, based on its fifty-use lifespan. Multiplying the paper napkin results by 50 results in 3,750 g of water and 12.5 g of carbon emissions. End of story? Well, from a material intensity perspective the result is clear the 100% recycled paper napkin is the environmentally superior decision (even the non-recycled paper napkin used less water, 75,750 g, but it did emit more CO2, 437.5 g).
For the paper napkin we have almost reached the end of the line. The average ton of landfill trash will emit 1.8 tons of CO2-equivalent (mostly methane) over 50 years (B. Davis, Ze-Gen, at CleanTech2007 conference, May 24, 2007). While the average ton of landfill waste is not 100% paper this gives us an idea of the emissions that can be expected from landfill waste. If we just assume this factor to be accurate for our paper napkin, we can add 450 g of CO2e to our fifty paper napkins.
Since the cloth napkin will be reused fifty times we need to consider the impact of washing and drying. Washing and rinsing the cloth napkin probably uses around 2.8 to 5 gallons of water per pound of fabric. If we assume a highly efficient machine this means 250 g of water per napkin, so 12,500 g ( 12.5 kg) of water over its lifetime. Add to that the use of soap and the energy used in drying.
Assume that we are using a 5000 W machine that can dry fifty napkins in twelve minutes, using 1 kWh. Using the CA average emissions factor ( 0.51 mT CO2 / MWh) we get 510 g of CO2 (0.001 MWh x 0.51 mT CO2 / MWh). If we go back and assume a 500 W washing machine this would add around 50 g of CO2.
So, here’s the final tally: Fifty paper napkins are responsible for 3,750 g of water use, and 462.5 g of CO2 emissions (although we can’t assume the landfill emissions factor to be quite accurate) and the cloth napkin is responsible for 240,548 g of water use, and 648 g of CO2 emissions.
Here are my recommendations… Cotton is very damaging from an environmental aspect (we didn’t even discuss pesticides and defoliants) so purchasing organic cotton is a good decision. Since Linen is made from flax we can assume that the environmental impact of linen napkins would be less. If you need to buy napkins, the 100% recycled ones clearly have a lower environmental impact. If you use cloth napkins, use biodegradable, phosphate-free soap, use the energy-saving settings, and line-dry them.
This is my best quick analysis of this question and I hope that Nick is happy with the result. If you have any better assumptions or additional comments to make please feel free to post them below. I look forward to an interesting discussion. Thanks for reading AskPablo!

Pablo Päster
Sustainability Engineer

20 responses

  1. That’s a shocking result. I am wondering where did you get the ‘used 50 times’ number. That doesn’t seem right to me… I think a cloth napkin must surely have a longer lifetime than that. What would be interesting for me is how many times would you have to reuse the cloth napkin for the impact of both types of napkins to be the same.

  2. I’m also wondering where the 50 uses came from. I’m 100% positive I would use cloth napkins much longer than that. And also, if it wasn’t really dirtied from one use, no need to wash it… reuse it again! It’s much easier to reuse a cloth napkin, paper napkins tend to tear and wet messes seep through them.

  3. The initial question was in regard to a restaurant so the napkin would be washed every time. Also, washing (especially if using bleach) degrades the quality of the napkin each time. I would actually be surprised if a restaurant uses a single napkin 50 times before retiring it.

  4. Aye… I think I’d definitely use the cloth napkins way more than 50 times, and not only that, if you use Napkin rings to identify who in your family has been using which napkin, then you don’t have to wash them every time (unless they get particularly dirty). At a restaurant, of course, they wash after every use.

  5. Also, you can pick up perfectly good vintage linen napkins in charity shops and boot sales for next to nothing — so that takes the manufacturing costs out of the equation. It’s an interesting comparison to make, but there are too many assumptions involved to say definitively which is better — if you made different initial assumptions, you would get a different result.

  6. My husband and I have used cloth (cotton) napkins for over 6 years… at most every meal. I have the same 10 that I originally purchased when we got married. They are organic cotton… and regardless of anything else, I certainly have used them many times more than 50 each. Additionally, I don’t necessarily wash one after a meal. For example, if I use one while eating my granola for breakfast, and the meal is not messy, then it just stays out for the next meal to be used. Often, a linen lasts for three meals (breakfast, lunch, and dinner), finally moving to hamper to be washed after the messier dinner. Thus, you get more meals per napkin between each wash, if the meals aren’t messy. And thus, the data could be better for the linen napkins.
    Thanks for the info, though… always good to read your thoughts, Pablo. It always gets me thinking! -smile-

  7. Wow! The results are shocking as a few people have stated. I also use my cloth napkins a few times (if they aren’t soiled) before washing them. I’m still using cloth napkins that are over 5 yrs old. After they look dingy or rip, I use them as rags to dust with, wipe down my counters, or wash the floor. I guess that leads to the discussion of paper towels or cloth rags. Just kidding, it will be the same answer.
    Pablo, thank you for being such an extraordinary researcher. Just when you think the answer is obvious, Mr. MIPS sets the record straight for us.

  8. I appreciate the calculations and, clearly, commercial vs. home use is an essential difference. We use one cotton napkin per person for several days and have several sets of napkins. When 3 sets are soiled, they are laundered along with other colored items on an energy efficient setting, and line dried. Like many others, I doubt the 50-use lifetime and would gauge 2 to 3 times that.
    Bear in mind that there are fuel costs for shipping paper napkins to the store and for the consumer’s travel to the store to purchase them. I have no idea how to gauge it, but you have to take into account the warehouse and supermarket space that are built and maintained to hold the inventory of paper products.

  9. We have cloth napkins (cotton, and for purposes of restaurant napkins ‘linen’ also means cotton — in fact some of ours at home are restaurant napkins). We wind up washing each napkin about once a week and we have napkins that are 20 years old and only starting to show wear. The restaurant napkins (purchased at a restaurant supply store) are newer and they are heavier than the oldest ones. Estimating 50 weeks per year (to allow for the occasional vacation) gives a useful lifespan of, I’d guess, 1000 to 1500 washes.

  10. It is unlikely that washing cloth napkins would result in more loads of laundry than a family does anyway. Several napkins thrown into a load in the washing machine hardly adds any volume. So from that perspective, I don’t think washing and drying environmental costs should count, except for restaurants.

  11. Too bad it was not made clear in the beginning that this was regarding napkins in a restaurant. Personally I prefer paper napkins, since you can never be sure how they were washed. Now your data means it is the best choice for the ‘green’ concerned. At home, however, we use cloth and they last yrs and yrs. Oh, BTW spell ck comment: your “You can now recieve AskPablo by weekly email!” …… receive. Thankxxx

  12. I’m sure that napkins aren’t the only laundry that restaurants have to do…..besides, I think most people use way more paper napkins than they need to. And don’t forget the environmental costs of the packaging for those paper napkins……Anyway, a really green solution to the “restaurant napkins” conundrum would be for restaurant guests to bring their own organic cotton napkins (obtained second-hand) from home and wash them with the rest of their regular laundry. Problem solved?

  13. Interesting analysis, but several of your premises are faulty. (Just ask your mother. )
    1) I have never had a cloth napkin that was used only 50 times. I have some that are 20 years old, and are still in service.
    2) Many cloth napkins are reused several times between launderings. Sometimes for multiple days. If used for three meals per day, for only two days, that’s six uses between launderings. At 50 launderings a year, we have 300 uses in one year alone.
    3) Often people use more than one paper napkin at a meal — that’s why “napkin holders” exist. Seldom do people use more than one cloth napkin per meal.
    Thanks though for working that all out.

  14. Most napkins are used for YEARS, not just 50 times… Obviously you don’t use cloth napkins on a regular basis if you can so easily pull out a skewed number like that for your calculations.
    I also noticed you based on 100% post consumer content paper napkins… Yet you did not factor with ORGANIC cotton? You factored with the best that paper has to offer against the worst that cotton has to offer… Yet again skewed.
    More than likely the average Joe is going to be purchasing Vigin wood fiber napkins…
    Oh, and by the way… I don’t know anyone who washes and entire load of nothing but napkins… They are tossed in with other clothing or other towels to fill a load to capacity and not waste water…
    Napkins are better off being line dried as the dryer causes the cotton to wrinkle tremendously. So the amount of power used for this is mute.
    I think you need to re-run your impressive calculations for real life situations.

  15. This case is based on restaurant use, not home use. So yes, the entire load of laundry could be napkins. And yes, the expected lifespan of a heavily bleached food service napkin is around 50 uses. Otganic cotton reduces the impact of growing the fibers but it does nothing to reduce the energy and water used in washing and drying. Therefore any difference in materials is negligible.

  16. A couple quick points:

    1. The points about usage are valid even if you want to stick with the restaurant analysis, and discount home usage patterns. Napkins/meal/person are not 1:1 by any realistic assumption. I would say that with all the waste its probably 4 or 5 paper usages to 1 linen, but 3 would be a conservative estimate. Go to a restaurant that uses paper, and you’ll see what I am talking about. Stacks and stacks get tossed around and used at each meal.

    2. The assumptions about recycling seem to always be that the raw material is magically free. It’s the same assumption that people use to claim that biodiesel is clean or that buying used somehow negates the initial build cost. Just because something is reused and/or comes from plants doesn’t mean there is a negligible cost associated with its production. Analysis is all about energy used over the lifetime of the product. A good energy/environmental analysis must account for the material from “cradle to cradle” (forgive the reference).

    If you really want to honestly answer this question in reference to recycled paper, you have to look at the cost of the original virgin pulp and factor that into a cost per use of the wood fiber. I would guess wood fibers get used 2 maybe 3 times tops. So when you average out the cost all the way through we don’t get the rosy picture of recycled paper. Switching between “virgin” and “recycled” seems to always be a way to fudge numbers to make a point.

    None of this mentions that recycled paper never comes from 100% used paper. There is pre consumer and industrial sources of course, but paper needs to have some sort of binding fibers (i.e. cotton or virgin pulp) that generally recycled sources can’t produce. It may come from old cloth or wood scrap, but to think that recycled paper comes just from the paper that gets processed out of what we throw into the recycle bin is overly simplistic. Remember “100%” legally only means 90something% in most cases and sometimes down to 70%.

  17. Pablo, I didn’t see any discussion of the energy used in growing and harvesting the paper (over and over as opposed to once for cloth napkins)

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