Introduction to Life Cycle Thinking

Every product we use on a daily basis has its own unique life cycle. The backpack you take to school, a pencil, your shoes, and even the building you live in! But what is the “life cycle” of a product? Let’s look at a simple, plastic water bottle, for example. 

To make a plastic water bottle, crude oil is extracted from the ground, transported to a refinery, and processed to make small plastic pellets. These pellets are melted, shaped, and blown like a balloon into the shape of a bottle. Bottles are then filled with water, labeled, packaged, and shipped to stores for people to buy. This is where you come in. You go to the store, purchase a water bottle, drink it, then throw it away. The bottle is then taken to a waste facility, where it is either sent to a landfill or recycled.

This is the full life cycle of a plastic water bottle – capturing the moments before, and after, you hold the bottle in your hand. Life cycle assessment (LCA) is a method for evaluating the comprehensive environmental impacts associated with a product, process or service throughout its entire life cycle, from the beginning of its life to the end.

Conducting a life cycle assessment is very complex, even for the simplest items – like a water bottle. We know that oil must be extracted from the ground to make plastic. But to do that, we need huge machines, and those machines have to be built in factories, using other materials, other machines, and so on.  Even once the bottles are made, they’re shipped across the country using trucks and fuel that also both have to be made. From this example we can see how quickly we run into a whole web of connections! This is why we need complex models to help us calculate the full life cycle impacts of a product, not just what’s right in front of us. This is life cycle thinking, considering the whole picture, helping us to make more sustainable choices. 

Conducting an LCA

To conduct an LCA, we need something called a life cycle inventory – or a list of all the things that go into making a product. Try practicing this idea with a simple household item. Take a wooden pencil, for example, and think about what makes up this product. We would list wood (the pencil body), rubber (the eraser), aluminum (the little band at the end), and graphite (the pencil lead). Importantly, we must not forget the energy used to manufacture the pencil, and the transportation to get the pencil to the store. If we want to be really detailed, we might want to consider the classic yellow paint coating the pencil. This is the type of thinking you want to employ when creating your life cycle inventory.

Real-World Questions

Now that you’ve got the basics of LCA down, let’s think about applications, and how it can help us in real-world situations. LCA lets us dig deeper into environmental questions and make smarter, more sustainable choices. 

Check out these examples – how would you weigh in?

• Should the school cafeteria switch to reusable trays instead of single use? How many times must the reusable tray be used to become the more sustainable choice?

• Is non-dairy milk better for the planet than dairy milk? Besides carbon footprint, does one use up more water or energy than the other? 

• Electric cars are known for being cleaner while driving, but what happens when we look at their entire life cycle, from production to end-of-life, are they still better for the environment? 

• How many books are equivalent to the life cycle impacts of one e-reader? Which is the more sustainable choice?

• Does location affect life cycle impacts? How might the impacts of a product change if made in the U.S. versus in China?

These are just a few of the questions LCA can help us answer. Which would you investigate first? What other “everyday” choices do you think LCA could help evaluate?