One of the most common questions faced by businesses in e-commerce and apparel considering sustainable packaging is what the best option is for their ‘poly bags’. These poly bags are generally thin protective bags that wrap products from the time they come off the manufacturing line to the time they either hit the shelf in the store or get sent out from the distribution center to the customer. 

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Currently the vast majority of businesses use standard single-use plastic LDPE bags as these are extremely cost effective (a lot of the time even free - built into the cost by the manufacturer) and functionally they do their job very well. However, from a sustainability perspective, the materials leave a lot to be desired. 

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So the question, which we get asked all the time, is ‘what is the ‘most sustainable’ poly alternative? In this article we are going to look at the data around three commonly discussed sustainable poly bags:

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• Compostable poly (home + industrial certified)
• Post-consumer recycled poly 
• Glassine paper (sometimes referred to by a brand called Vela poly) 

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Functionality

The first thing to consider is obviously the functionality of the material i.e. will it actually work for your business and supply chain. The three most important considerations here are; transparency (or lack thereof), strength and breathability. Breathability isn’t immediately obvious as a consideration but it is important as changing temperatures or humidity levels can lead to ‘sweating’ or condensation inside the packaging, which in turn can obviously

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Sustainability 

Beyond functionality, the next most important series of considerations relate to sustainability (we think anyway). Most people tend to jump to whether something is recyclable or compostable as the only consideration, but it is important to scratch under the surface to understand how they are made and how they are actually likely to be treated at end-of-life.. 

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Material composition and reliance on fossil fuel. 

Not all materials are created equal, a lot of the time what appears to just be ‘poly’ or ‘biodegradable poly’ is in fact blends of several different raw material components (also known as feedstocks). In particular, the material commonly used to make compostable poly actually usually contains mostly virgin fossil fuel** due to the use of a very cost effective biodegradable polymer called PBAT. 

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See below for a breakdown of how these materials are most commonly produced. 

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^{**important to note that this is not always the case, some compostable poly can be made 100% from plants. Grounded can produce home compostable poly made 100% from plants.}

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Carbon Footprint 

The next important thing to consider is carbon footprint. Carbon footprint refers to the overall greenhouse gas emissions associated with the production, logistics, distribution, and disposal of a particular product or material. 

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Although Carbon is often talked about, it is not well understood. With our Scope data platform we are able to model out the carbon emissions from every stage of a packaging material or product, from raw material to end-of-life. Using that platform we have looked at the likely carbon footprint for 100,000 units of ‘medium’ sized poly bags, and the results are surprising. The ‘biodegradable’ or ‘compostable’ poly has by far the largest carbon footprint. This is largely due to the heavy use of fossil fuel in manufacturing, and subsequently it getting released into the atmosphere if it biodegrades in the wrong environment.

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End-of-Life 

The next critical piece is the “end-of-life”. End-of-life refers to what happens to a product once its intended purpose has been fulfilled. For packaging that generally refers to landfill, recycling, composting or re-use. 

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Waste management is a complicated field. Different regions have different infrastructure for collection and management, and different materials need to be treated distinctly in order to be recycled or composted properly. Different types of plastics for example have very different recycling rates. It is important to understand these considerations at both a regional and material level in order to inform the best packaging decisions.

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For the purposes of this article we have made some conservative assumptions about material treatments in the USA, again based on an assumption of 100,000 poly bags. One thing to note in relation to Glassine paper is that, although it is theoretically kerbside recyclable, it is very unlikely to get recycled at the same rate as other paper, as it is often mistaken for ‘baking paper’ which many recycling facilities don’t like as it has a silicon non-stick coating applied to it.

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Material Circularity 

The final data point that we look at is the 'Material Circularity Indicator' or MCI calculation, designed by the Ellen MacArthur Foundation. This particular component is probably the least well understood, but we think it is the most important sustainability metric in packaging as it takes into account three key factors; the amount of renewable or recycled content incorporated, its utility and finally its intended end-of-life destination, and the likelihood of it ending up in that intended destination. 

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A circular economy is a system that requires us to reconsider the entire life cycle of our products and resources by designing out waste. That means making use of materials and technologies that extend the lifespans and potential reuse value of the things we produce, while minimizing unintended waste.

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See our article on understand the MCI score here

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Aesthetics & Price

Beyond the sustainability data, the final consideration is really aesthetics and price and these three alternatives are all very different.

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Overview & Conclusions 

In this case there is a relatively clear winner and loser from a sustainability data perspective, but there are functional compromises and different price tags associated with all materials. 

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However, the data is not always so clear cut and some businesses will have specific strategies to maximize certain outcomes; carbon footprint, use of recycled content, recycling rates etc, and these are all good positions to have. The most important thing is to do something over nothing and to consider the data when making a decision. 

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If you would like access to the software please reach out and one of our team can give a demo and run you through how it works. You can also take a look at some of our other ‘case studies’ to see what other businesses and brands are doing. We have also included a video from one of our co-founders talking through the considerations for sustainable poly bags and pointing out the 

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It is important to note that as part of this article we have not considered virgin plastic or ‘poly’ as we think that is not the right thing to use. 

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See our Princess Polly case study here