A new Canadian life cycle assessment (LCA) study examining milk packaging systems found that lightweight plastic formats often outperform heavier alternatives such as single-use glass across multiple environmental impact categories, while the performance of reusable systems depends heavily on reuse rates, transportation distance, and energy sources.
The research, conducted by University of Waterloo Master of Environmental Studies graduate Alexander Cha under the supervision of Goretty Dias, examined the environmental impacts of multiple milk packaging systems used in Canada. The study compared high-density polyethylene (HDPE) jugs, PET bottles, plastic milk pouches, liquid paperboard cartons, and both single-use and reusable glass bottles.
The thesis, titled Life Cycle Assessment of Milk Packaging in Canada: Evaluating Reusable Packaging under Prospective Energy Grid Scenarios, evaluated packaging impacts under both current electricity conditions and a prospective net-zero Canadian grid projected for 2050.
Life Cycle Assessment Examines Canadian Milk Packaging Systems
Using ISO 14040/14044 aligned methodology, the study modeled packaging systems in openLCA with the ecoinvent database and ImpactWorld+ methodology. The functional unit was 12 liters of refrigerated pasteurized milk.
One of the study’s clearest findings was that the production stage dominates overall environmental impacts for most packaging formats. Lightweight flexible plastic milk bags performed best across most impact categories, while single-use glass consistently generated the highest impacts.
Reusable glass systems showed improvement as reuse rates increased, but the analysis highlighted important tradeoffs involving transportation and sanitization.
“Glass is a good example of why sustainability can be more complicated than it looks,” Cha said in a University of Waterloo article discussing the findings. “The bottle may be reusable, but it is also heavier, which means more energy is needed to produce and transport it. It also has to be collected, washed, refilled, and reused enough times to make those added impacts worthwhile.”
Reusable Glass Packaging Depends on Efficient Reuse Infrastructure
Cha noted that reuse systems depend heavily on logistics efficiency and infrastructure performance.
“If the bottles travel too far, are not reused enough times, or require too much energy and water to clean, the benefits of reuse can become much smaller,” he explained.
The findings reinforce a growing discussion within reusable packaging and circular economy circles that sustainability outcomes depend less on simple material substitution and more on overall system design and operational efficiency.
Under a decarbonized Canadian electricity grid, reusable glass systems improved significantly and outperformed some single-use alternatives. However, the study found that reusable glass rarely surpassed lightweight reusable plastic systems in overall environmental performance.
Single-Use Plastics and Sustainable Packaging Tradeoffs
The research also cautioned against broad assumptions that all plastic packaging is inherently unsustainable.
“The most responsible approach is usually to reduce unnecessary consumption first, choose products with efficient packaging systems, and make sure the packaging is compatible with your local recycling or recovery infrastructure,” Cha said. “End-of-life management matters just as much as the material choice itself.”
The study’s conclusions may resonate within the reusable transport packaging sector, where system-level thinking increasingly shapes discussions around circularity, carbon reduction, and infrastructure investment. Rather than focusing solely on replacing one material with another, the research suggests stronger environmental gains may come from reducing packaging mass, improving reuse efficiency, and strengthening collection and recovery systems.
Decarbonized Energy Grids Could Shift Packaging Sustainability
The thesis also highlights the importance of evaluating reuse systems within the context of future energy transitions. As electricity grids decarbonize, electricity-intensive processes such as washing and sanitization become less environmentally burdensome, potentially improving the competitiveness of certain reusable systems over time.
At the same time, the study acknowledged limitations related to data quality, availability, and the still-evolving ability of LCAs to fully quantify microplastic impacts.
Cha now works with Cleanfarms Inc., collaborating with stakeholders across the agricultural sector on stewardship and extended producer responsibility programs.
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Rick LeBlanc, EMBA, is the founder and editor of Reusable Packaging News (subscribe to the free newsletter) and editor of Western Pallet Magazine. A supply chain journalist with more than 30 years of experience, he specializes in pallets, reusable packaging, material handling and related operations. Rick is co-author of Pallets: A North American Perspective and Pallets & Progress: A Collected History of Pallets and Palletized Handling 1922–1945. He is also an advisory board member of the Virginia Tech Center for Packaging and Unit Load Design. Read Rick’s full bio.
