It was a month ago when I heard the surprising news that milk packaged in cartons has the best environmental performance as compared to other packaging materials. Do they, really? Aren’t the reusable deposit bottles world famous for being green? Well, actually, milk bottles are white or brown, of course, but environment-wise their reputation is outstandingly green. In order to find some reliable information, I took the time to scan two comparative LCAs on beverage packaging, and guess what: the returnable glass bottle is far from being the best. LCA, for those who aren’t familiar with the initials, stands for life cycle assessment, a normed process for finding out all environmental effects a product generates: from raw material extraction, to production, to transport, to consumer, to disposal. The first LCA compared cartons with single use PET and HDPE bottles, the two main plastics used to package milk.
A recent, Europe-wide Life-Cycle Assessment, conducted by the Institute for Energy and Environmental Research (IFEU), for SIG Combibloc has confirmed that, compared to disposable high-density polyethylene and PET bottles, carton packs for UHT milk have a significantly better environmental profile—particularly with respect to CO2 emissions, use of fossil resources, and consumption of primary energy.
In the 1-L format, carton packs generate 34% less CO2, use 56% fewer fossil resources, and consume 30% less primary energy compared to HDPE multilayer bottles; when compared to disposable PET bottles, these figures are 45% for CO2, 57% for fossil resources, and 36% for primary energy.
To make things easier to compare, the only impact category I focus on in this article is climate change. Environmental performance is not only about climate related carbon emissions, of course, and some packages might score better in terms of water use or ecotoxicological potential, for instance. LCAs are precise, they consider all kinds of impact categories. However, I chose to compare only the carbon emissions from different packages. I beg your pardon for that; it is, however, more comprehensible.
Let’s take a look at another comparative LCA. The British NGO and recycling promotion organization “WRAP” (Waste & Resources Action Programme) compared the most common types of milk packages on the UK market in January 2010. First of all, it has to be said that on their island, the British can be funny sometimes. Unlike the rest of Europe, they don’t stick to the metric system across different packaging materials. But the cartons, at least, adhere to the 1L size.
In contrast, glass milk bottles come in the one imperial pint (0.568 L) size, and HDPE bottles come in the two imperial pint (1.136 L) size. To compare different sizes, every LCA defines a functional unit. In this case, the study’s functional unit depends on the container type. To match the volume of 1000 1-pint-bottles, you take 500 2-pint-bottles or 568 1-L-cartons. This is important in order to calculate comparable emissions for individual packages.