How to account for environmental impact of second hand goods

Question

I've been trying to understand and reduce my impact on the environment, and particularly to understand what a really sustainable lifestyle would look like. I (roughly) get the concepts of ecological footprint and planetary boundaries.

But one of my difficulties is how to account for the impact of buying secondhand goods. I tend now to buy nearly everything from charity shops, eBay, etc and buy very little new "stuff". A simplistic viewpoint is that these have zero impact (other than shipping and other overheads). But that seems like a bit of a cheat. In particular it fails the test of "would it work if everyone lived like this" since it relies on someone else having bought things new. A bit like countries offshoring all their carbon emissions and claiming to have reduced their footprint.

Any ideas for how to do this in a practical way?

Answer 1

The market value of the goods is often indicative of the remaining useful life of the goods. If you know the environmental footprint of the product when new, it seems reasonable to assume that a purchaser of the goods (second hand) is to be responsible for a share of that impact based on the proportion of useful life remaining.

For example, if there exists a car that cost $10,000 (when new) with a footprint of 5,000 environmental-harm units (whatever they may be; this is just an example. This works out to be 1 unit per $2), and you then purchase it for say $6,000 then you should consider yourself responsible for 3,000 units of environment-harm (ie still 1 unit per $2).

Of course, if you treat the item well and onsell it for $5,000 then you could consider that you've reduced your impact.

This kind of simple assumption is never going to be completely accurate, especially with factors such as government subsidies of environmentally damaging activities, but it's a starting point.

This idea holds up well in some key ways:

• An item taken that was otherwise heading to landfill could be considered as having a zero dollar value, and if that's accurate then it's reasonable to assume you aren't responsible for any of its impact of manufacture.
• The higher the price you pay for a second hand item, the more likely it will be that the seller replaces the item and causes additional environmental impact. It's therefore reasonable to consider that when you choose to take up their offer at the given price, you are responsible for additional environmental impact.

Answer 2

What you are asking is generally referred to as the 'allocation problem'. There are a number of allocation methods that are often used in assessing the environmental impact of a product or service, but each allocation method has it pros and cons. Since the chosen method can have a big influence on the outcome of a study, allocation is an important and even controversial topic as experts have different opinions on which allocation method is best in which situation.

Some examples of often used allocation methods:

• portion of mass reused: relatively easy to determine for physical products, leads to low impacts, if you reuse the entire product the impact is 0 (as you mentioned in your question)

• portion of (embodied) energy: similar to mass reused, but may be more difficult to determine

• market value: this is nicely explained in Highly Irregular's answer, value may be difficult to determine correctly, prices can be volatile

• no/avoided allocation: may not be very realistic, leads to higher impacts, in your case you have the full impact.

Which method is chosen in practice depends on various things; the type of product, what environmental impact you want to measure, what data is available to you. Personally, in your case I'd go with market value.