Image borrowed from The New York Times
From countries to individuals, everyone is looking to do their part in reducing their carbon footprint. Participating in the “sharing economy” can be a great way to go about this, whether it is car-sharing with platforms like Car Next Door, accommodation with Airbnb or tool-sharing with Library of Things like Share Shed. But how much carbon emissions would you actually save by borrowing and sharing instead of buying? In this article, I will give you a quick overview on how it can be calculated and an example using a common tool (a power drill) that can be borrowed here at Share Shed! For those interested in the research behind the numbers quoted in this article, please refer to the footnotes scattered throughout.
First, your carbon footprint is usually given in kilograms or tonnes of carbon dioxide equivalent (abbreviated as kgCO2-e or tCO2-e). This standard unit simplifies carbon emissions accounting and allows all different greenhouse gases (from methane to hydrofluorocarbons) to be converted and summed. Conversion factors for different gases can be found from the National Greenhouse Accounts Factors.
To calculate carbon emissions saved from sharing, we assume that one instance of borrowing suppresses production of one item. Hence, we need to know the carbon footprint of the product in question. A product carbon footprint is a measure of the direct and indirect greenhouse gas (GHG) emissions associated with the product’s life cycle (manufacture, distribution, use, recycle and disposal). This can be calculated with a Life-Cycle Analysis (LCA) focusing on GHG emissions only excluding other environmental impacts. Unfortunately, due to the complex nature of modern tools and manufacturing process, a product carbon footprint is currently expensive to commission so only high value products or bulk building materials have carbon footprints calculated. An example would be the iPhone 11 at 89 kgCO2-e for the 256GB variant.
Fortunately, there has been some European research from organisations such as WRAP (UK) and CONCITO (Denmark) that provide us with estimates of some products. For example, an electric drill is estimated to have a carbon footprint of 28 kgCO2-e (excluding the use phase) while it is estimated that production of a tool generates around 7 kgCO2-e per kg of material. These numbers can be used as rough rules of thumb for an order of magnitude estimate for a product but does not constitute an accurate carbon footprint for purposes of carbon projects. Therefore, an upper limit of 28 kgCO2-e is a reasonable estimate for carbon emissions reduction attributable to each unique instance of borrowing an electric drill. However, the actual emissions reduction is likely lower due to various factors. An example is if the same person borrows the drill at 3 different instances, it would only represent a single reduction of 28 kgCO2-e instead of 84 kgCO2-e as it is assumed that the person would only buy a single drill and use it at those 3 instances.
Some items have a high energy requirement over their usable lifespan compared to their embodied carbon during the manufacturing phase. These would have a lower carbon reduction impact if borrowed. However, items that might be used very infrequently but have high embodied carbon during manufacturing offer significant carbon reductions when borrowed instead of bought for private use. For example, an electric drill in an average household is estimated to be used only around 18 minutes over its entire life span. In Figure 1 above, top electronic goods in the UK were split into dominant use phase or dominant manufacture phase accordingly to energy required at each phase.
So, if you are mulling over whether to splurge out on that fancy electric drill, edge grinder or another fancy tool at Bunnings, why not think about how often you will use it? If it is only once every few months, borrow from Share Shed to save yourself money and you will help reduce carbon emissions at the same time!
Written by Junyan Tan