Which Is Greener: Styrofoam or Ceramic Mugs?

Author’s Note: A Chicago Tribune reader wanted to know: Are disposable coffee cups made of Styrofoam more or less harmful to the environment than reusable mugs? Here’s how I answered, with much help from sustainability engineer Pablo Päster. 

The debate over coffee cups-disposable or not-happens torunneth over with tough-to-measure variables. For instance, do you use a dishwasher? Is your model energy efficient? And: Just how clumsy are you? (Reusable mugs: Useless when broken.) Scientists analyze this issue in myriad ways, but overall, consensus is that brew imbibed from reusable, ceramic mugs is the most sustainable option.

But there’s many a slip twixt cup and lip. To reap environmental rewards of the mug, you’ll need to hand rinse it–putting it in your (energy-efficient) dishwasher only when absolutely necessary. That’s according to Pablo Päster, a San Francisco-based sustainability engineering consultant who also writes a column at AskPablo.org on the science of sustainability, including a technical analysis of this very issue.

In his analysis, Päster found that a ceramic mug has a higher total “material intensity”- a measure of resources used to manufacture a product (like the extracted clay and gas to heat the kiln)-than a Styrofoam cup. But the mug’s reusability-which means it can provide multiple “service units”-justifies its higher material intensity after about 46 uses. “If you have one cup of coffee daily for a year, that’s 365 ‘service units,'” says Päster. “That can be accomplished with either 365 disposable cups or one reusable mug.”

Factor in maintenance and the plot thickens: If you wash your mug in the dishwasher after every use, polystyrene could end up being a more efficient choice-at least in terms of energy use, says Päster. He’s found that even when set to the most efficient cycle, dishwashers gorge on so much water, electricity and natural gas that it’s more efficient to clean the same amount of dishes by hand-and under a continuously running tap at that. So, as long as you cut back on machine washing, you’ll do right by the environment with a reusable mug.

To help sell your head suit on the benefits of mugging it, start by making a case for the environment: Styrofoam’s upfront cost is lower than that of paper or reusable mugs. And it insulates well. But polystyrene never deteriorates. It can also melt into the hot beverage it’s designed to hold. One EPA study of human fat biopsies found styrene residues in 100% of the samples tested. Paper cups bring up less gruesome details. But because they’re lined with a plastic coating, they pose challenges from a recycling standpoint.

From a business perspective, Päster-who’s helping his own company make the shift-found that a bulk order of mugs came to about $2 each. If that figure isn’t negligible when compared to your company’s payroll, then the time to look for more lucrative work is now. Meanwhile, if each disposable cup costs, say, one cent, your company recoups the cost of each mug in 200 days.

“And a ceramic mug can potentially last for years,” says Päster, who adds that disposal costs shouldn’t be overlooked. For larger companies especially, all those cups take up Dumpster space that ceramic mugs-sitting pretty in the cupboard-do not, increasing trash-collection costs.

To seal the deal, offer up the latest buzz from research on business success and sustainability. Free mugs alone won’t inspire loyalty beyond reason. But businesses that support multiple efforts toward a sustainable world stand to see more than environmental benefits. “When employees see that their company cares about the environment as much as they do,” Päster says, “it can have a positive effect on everything from employee recruitment to retention and morale.”

Read Päster’s full analysis and check out his site.

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