I’m trying to get some data on how many CO2 emissions are saved with each tonne of repaired and reused items. Looking at the overall Fixometer stats, this seems to be around 9 tonnes of CO2 emissions for each tonne of waste saved from landfill. Does this seem about right? Are there any official publications to back this up?
And am I right to think that 1 tonne of CO2 emissions are the equivalent of around 17 trees grown from seed for 10 years? (Again, would be great to have some publications to back this up and reference!)
Great questions! Happy to share the data and methodologies we use
What are you hoping to use this data for? (the purpose might affect which methodology and source data is most useful)
CO2e saved per repair
For the Fixometer, our approach is to use an average embodied CO2e figure for each individual product category, as this can vary widely for different types of products (e.g. a laptop will represent significantly more embodied CO2e than a t-shirt).
It is possible to simply divide the kg of CO2e saved by the weight of repaired items on the Fixometer to produce a CO2e/kg figure. But I’d strongly reccomend against doing that, as the resulting figure would likely be incredibly inaccurate (especially without weighting different product categories to form a representative mix for the application you have in mind).
You can find the raw data we base our calculations on for each product category here:
The ‘Raw data’ tab in that spreadsheet contains links to the sources we used when compiling the data.
It’s also important to note that when calculating the impact of a sucessful repair, we make some key assumptions:
that the product’s useful lifespan will be extended by an average of 50% (therefore displacing 50% of the embodied CO2e of a new replacement product)
that the product will continue to be used by its original owner (the most common scenario for a community repair event)
that any extra CO2e produced in the process of repairing a device is negligible (this isn’t always the case in practice)
As such, our methodology hasn’t been designed for reuse scenarios outside of community repair event settings (i.e. it wouldn’t necessarily be appropriate for a reuse shop, for example). We developed it primarily as an educational tool, to help people better understand the connection between consumer products and upstream environmental impacts (i.e. the climate impacts of making products).
There’s more info about the method and data we use to calculate CO2e stats on the Fixometer here:
For reference, since we put together our own data, a couple of other resources have sprung up that might be useful. In particular, it might be worth taking a look at ADEME’s excellent Impact CO2 tool:
Tree-based CO2e equivilencies
To calculate the equivilent number of trees it would take to absorb the same amount of CO2e, we use two different calculations depending on the amount of CO2e in question.
For small amounts of CO2e
For small amounts of CO2e, we use the metric you mention: the equivalent number of tree seedlings grown over 10 years. We use data from the US EPA for this:
36.4 lbs C/tree/year × (44 units CO2/12 units C) × 1 metric ton/2,204.6 lbs = 0.060 metric ton CO2 per urban tree planted per year
For larger amounts of CO2e, we use a different equivilency (as we feel it’s easier to understand at bigger scales and we needed a different method to help us represent it visually). We use the methodology from Winrock’s Forest Landscape Restoration (FLR) calculator, which in turn uses data from their Global Removals Database:
12 tonnes of CO2e sequestered per hectare of trees per year (broadleaf trees grown in a woodlot in England)
What James says.
I would caution against such simplifications in general.
It’s a bit like when a local council that I know of was much more interested in paper recycling than electronics reuse because the only criterion they were interested in was tonnes of material.
What relevance does the tonnage have to the amount of CO2 saved? Maybe the number of items saved would be more useful as a measure, but even that is is of very limited use as James explained.
Thanks so much for this, these resources are excellent! Loving the Impact CO2 tool and will definitely use that! (And not generalise the CO2 emissions)
What James says.