The first literature review is a research paper highlighting the manufacturing process and energy use conducted on eyeglasses in 2024.
"Evaluation of manufacturing processes, materials, and energy efficiency in the Italian Eyewear Industry: The potential of electric heating methods towards industry 5.0", a research paper written by José David Betancourth Mendoza, provides a detailed analysis of the Italian eyewear industry, including a focus on history, materials, manufacturing processes, energy efficiency, the transition towards Industry 5.0, and the introduction of electric heating. Mendoza introduces many interesting points in his research, but his most notable contribution is the discussion of introducing electric heating methods, such as induction, radiofrequency, and microwave heating, to improve energy efficiency within the eyewear manufacturing process. The electric heating technology provides precise control over the entire heating process, reducing energy consumption through specific targeting. Additionally, this technology reaches high temperatures quickly, reducing the time required to weld, dry, or cure in manufacturing, thus lowering energy use. This idea comes from the EU’s transition towards Industry 5.0, a vision set by the EU to put people and the planet at the center of manufacturing processes. Additionally, Mendoza mentions that the introduction of electric heating methods would align with the adoption of Best Available Techniques (BAT) and some certifications such as Certified Sustainable Eyewear (CSE), reinforcing the industry's move toward sustainability. However, it should be noted that U.S. manufacturers, such as Warby Parker, are not required to comply with these regulations.
While Mendoza’s research provides valuable insight into the Italian eyewear industry, it has some gaps. This research does not investigate the long-term impacts of new materials and electric heating technology. Additionally, the study does not utilize tools such as Life Cycle Assessment (LCA) to document environmental impacts. Another limitation noted, this paper seems to highlight only the positive effects of introducing electric heating to the manufacturing process and skips over any barriers such as cost, infrastructure adjustments, or industry resistance to adopting new technology that might occur. Furthermore, the research study focuses exclusively on the Italian eyewear industry, whereas our LCA analysis examines eyewear produced by Warby Parker in the United States. This difference in geography leads to potential differences in manufacturing regulations and standards that must be implemented and followed.
Overall, this research provides us with a general understanding of the Italian manufacturing process and possible improvements that can be made in the Warby Parker manufacturing process such as a move towards electric heating and more sustainable material choices. By conducting an LCA on Warby Parker’s eyeglasses, we can build upon Mendoza’s work by providing insights into energy efficiency and regulatory differences outside the EU, creating a more comprehensive understanding of sustainability in eyewear manufacturing.
The second literature review is a research paper comparing two manufacturing processes that was conducted on eyeglasses in 2021.
“A Holistic View on Sustainability in Additive and Subtractive Manufacturing: A Comparative Empirical Study of Eyewear Production Systems” written by Sam Solaimani, Alireza Parandian, and Nabi Nabiollahi is an article that explores the impact of two manufacturing methods used to produce eyeglasses. These two methods include additive manufacturing (Selective Laser Sintering) and subtractive manufacturing (Computer Numerical Control Milling). In relation to our LCA assessment of Warby Parker eyeglasses, the manufacturing process Warby Parker uses is Computer Numerical Control Milling (CNC), or subtractive manufacturing. The assessment discussed in the article was performed within the system boundary of raw material to assembly. The manufacturing methods were assessed from an economic, environment, and social viewpoint. The article emphasizes the need to consider trade-offs in production processes and an overall holistic view when assessing sustainability of a process. This means that all interactions and processes within the systems are accounted for to make for a more well-rounded sustainability impact assessment.
Several conclusions and results were drawn from the assessment of the two manufacturing methods, additive and subtractive manufacturing. The results were assessed in terms of economic, environmental, and social impacts. In terms of the economic impact, it was concluded that in additive manufacturing, the cost of raw material and the lead time is lower. In terms of the environmental impact, it was concluded that additive manufacturing is more energy efficient. Though, it is mentioned that the coloring process in AM could also have negative effects as it requires the heating of water. In discussion of the social impact, it was concluded that subtractive manufacturing requires more manual labor as it requires craftsman skills and is labor intensive in the polishing phase.
The article states that the study published in 2021 involves two European based manufacturers. Compared to the LCA analysis we will conduct, there will be a difference in data quality as this study was performed on European manufacturers rather than American manufacturers, which will be our focus. The manufacturing methods assessed were Selective Laser Sintering (additive manufacturing) and Computer Numerical Control Milling (subtractive manufacturing).
An additional point worth mentioning in the article is that in addition to the quantitative assessment of the manufacturing methods, qualitative assessments were carried out in the form of interviews. These were interviews of people from both additive and subtractive manufacturing fields which enriched the study overall. These interviews strengthened the assessment because they provided insight into how the findings could be applied or used in real-world, practical situations. Overall, this study offers valuable insights into the sustainability trade-offs between additive and subtractive manufacturing, reinforcing the importance of a holistic assessment approach and providing a foundation for comparing Warby Parker’s manufacturing processes through our own LCA analysis.
The final literature review is a finished Life Cycle Analysis that was conducted in 2019 on two eyeglasses: Neil and Pierce.
The case study, Life Cycle Analysis of the Eyeglasses by Neil and Pierce, serves as an important precedent of eyeglass Life Cycle Assessments (LCA), and provides valuable insights into the limitations, gaps, and conflicts that can arise in such research. The goal of the LCA was to specifically focus on the materials used to manufacture the glasses, the production processes, and the transportation and end of life phases. By using results and knowledge about environmental impacts of the two glasses, the company aims to decrease the impact through research and development (Ace, Tate & De Lange, 2013). To conduct their analysis, the study used the Ecoinvent v3.5 database to study the environmental impact categories, material inputs, production processes, transportation logistics, energy consumption, and waste management. This database is crucial for developing a comprehensive picture of the life cycle of products and understanding the areas with the most significant environmental impacts.
The case study also acknowledged limitations, conflicts, and gap in the research which can help future eyeglass LCAs. One challenge in the study is the differing production routes used in the manufacturing of the two eyeglasses. Due to the variety of processes involved, multiple averages and calculations were employed to create the LCA data, which introduces a degree of uncertainty in the results. Even though the data is geographically relevant and representative, the researchers acknowledged that certain assumptions were made that could potentially affect the accuracy of the findings (Ace, Tate & De Lange, 2013). This limitation emphasizes the complexity of LCA, especially when studying products like eyeglasses that are manufactured through different production chains across various locations. Despite these challenges, the Life Cycle Impact Assessment (LCIA) phase did not identify any significant gaps in the inventory data provided by Ecoinvent. This inventory data included calculations of material usage, transportation, or waste processing; therefore, it is apparent that the data set used was within the study’s scope.
In the interpretation phase of the LCA, there are sensitivity analyses conducted on the frames and end of life stage for both Neil and Pierce glasses. A sensitivity analysis determines the influence of variations in assumptions, methods and data on the results. The purpose of the analyses are to compare the results with given assumptions. For the Pierce frame, there were three sensitivity analyses conducted (Ace, Tate & De Lange, 2013). The first sensitivity analysis was on the production of the acetate frame which had a lot of data. However, the second sensitivity analysis was on the production of the acetate slab, and there was limited data on the production process which led to less data understanding. The limited data also led to potentially inaccurate results since the baseline and energy consumption was about equal (Ace, Tate & De Lange, 2013). Similarly, the Neil glasses had the same data limitations and gaps. Since no data was available for the production of the acetate Neil slab, data had to be estimated in Ecoinvent. Additionally, not all supply chain partners were able to provide a detailed LCA of their materials (Ace, Tate & De Lange, 2013). Therefore, if the researchers had this information and data they would help enable their Ace & Tate stakeholders to have a better understanding of the environmental impacts of the material production.
In conclusion, the researchers believe that in the future, reliance on databases may become lower as more details on the data are gathered. With the resources available, they performed the LCA thoroughly and accurately, and implemented an appropriate impact assessment method (Recipe) for calculations. The researchers also believe that “the LCA report fully complies with the ISO 14044 norm, which ensures quality and transparency of the LCA” (Ace, Tate & De Lange, 2013). Overall, the Neil and Pierce LCA study provides an important analysis on the complexities of assessing environmental impacts in product manufacturing, while further emphasizing the need for more data availability.
These studies highlight important sustainability considerations in eyewear manufacturing, including energy-efficient production methods, additive vs. subtractive manufacturing trade-offs, and gaps in end-of-life recycling. However, none have conducted a complete LCA on Warby Parker’s eyeglasses within the U.S. market. Our study aims to address this gap by analyzing material impacts, production emissions, and disposal challenges.
According to the Warby Parker website, the life cycle of a pair of glasses begins with careful design and material selection. Materials such as custom cellulose acetate and lightweight titanium are selected for their durability and quality. Extracting cellulose acetate (from wood pulp) and titanium requires significant energy and natural resources. Mining titanium contributes to habitat destruction, while acetate production involves chemicals that can impact air and water quality.
Using CNC machines, the raw materials are cut to shape. Using CNC machines reduces material waste, though energy consumption is still notable. The next step involves polishing the frames using wood chips and German wax which are relatively sustainable compared to synthetic alternatives. However, energy consumption and byproducts like dust and chemical residues may affect air and water systems if not properly managed.
Technicians hand-assemble the components and perform quality checks to ensure each pair meets durability standards. The assembly process is labor-intensive, which reduces the need for energy-consuming machinery. Minimal environmental impact occurs at this stage.
Once assembled, the glasses are packaged and shipped to customers. Packaging materials, especially plastics and non-recyclable components, contribute to landfill waste. However, using sustainable packaging—like recycled paper and biodegradable materials—can mitigate this. Transportation, whether by air, sea, or land, results in greenhouse gas emissions.
At the end of their lifecycle, Warby Parker encourages donating old glasses at their stores. Donated glasses are sent to Lions Club Eyeglass Recycling Centers, where they’re cleaned, calibrated, and repaired. Through the Lions Club Recycle for Sight program, refurbished glasses are distributed globally to communities in need. This initiative promotes sustainability by extending the lifespan of eyewear and reducing waste. However, improper disposal—such as discarding glasses in landfills—contributes to waste accumulation.
In order to conduct our LCA, we have made three key assumptions including the lifespan and frequency of use of the eyeglasses, recycling rates of material during end of life stage, and geographical considerations. Based on research from Warby Parker, Americans should get their eyes checked every one to two years (Srednick, 2024). Therefore, if prescribed corrective glasses, we assume consumers will obtain new glasses within this one-year timeframe. Additionally, according to Oscar Wylee, it is necessary to wear prescription glasses as often as prescribed by your optometrist, with typical corrections intended for daily wear (Oscar, n.d.). Therefore, we make the assumption that prescription glasses are worn all day, or about 12 hours a day. For our recycling assumptions, we assume that only the titanium portions of the glasses are recyclable. Titanium has a high recyclability rate, with nearly 60% being recycled (Circular Economy, 2023). In contrast, less than 10% of polycarbonate is recycled due to high costs, and cellulose acetate frames are generally not recycled due to limited infrastructure. Finally, our geographical assumptions include where our materials are sourced from, where everything is manufactured and assembled and lastly where the product is being distributed too. Materials such as cellulose acetate are sourced from Italy, beeswax for polishing from Germany, and titanium for screws is primarily sourced from China. Manufacturing and assembly take place in New York and Nevada, with distribution occurring both domestically and internationally.
Ultimately, the literature reviewed highlights the diverse manufacturing processes across different regions, time periods, and techniques, providing a foundation for understanding the eyewear industry's sustainability challenges. Through our LCA of Warby Parker’s Durand eyeglasses, we aim to build on these environmental impacts and further explore opportunities for improvement.
Ace & Tate, & De Lange, M., from. (2013). Life Cycle Analysis report. In Ace & Tate. https://assets.ctfassets.net/utaji99zkvj6/54Bbp0yCIH2i8Pb7GtBzXF/e769d8fcc03271fe8bbbf62326806470/A_T_-_LCA_Report.pdf
Circular Economy: Recycling | NIST. (2023, November 7). NIST. https://www.nist.gov/el/applied-economics-office/manufacturing/circular-economy/recycling#:~:text=In%20the%20US%2C%20metals%20are,(Statista%20Research%20Department%202022).
How Warby Parker Glasses are Made. Warby Parker. (n.d.). https://www.warbyparker.com/how-our-glasses-are-made?msockid=08a01de33ee668a53ab508f03ff169c4
Mendoza, J. D. B. (2024). Evaluation of manufacturing processes, materials, and energy efficiency in the Italian Eyewear Industry: The potential of electric heating methods towards industry 5.0 [Masters Thesis, University of Padua]. https://upcommons.upc.edu/bitstream/handle/2117/422049/BetancourthMendoza_JoseDavid.pdf.pdf?sequence=2&isAllowed=y
Oscar Wylee. (n.d.). Should I wear my glasses all the time? Benefits and risks. https://www.oscarwylee.com.au/glasses/wear-all-the-time#:~:text=It%20is%20necessary%20to%20wear,as%20myopia%2C%20hyperopia%20or%20astigmatism.
Solaimani S, Parandian A, Nabiollahi N. A Holistic View on Sustainability in Additive and Subtractive Manufacturing: A Comparative Empirical Study of Eyewear Production Systems. Sustainability. 2021; 13(19):10775. https://doi.org/10.3390/su131910775
Srednick, D. (2024, September 10). How Often Should You Get an Eye Exam? https://www.warbyparker.com/learn/how-often-should-you-get-an-eye-exam