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Part 2: How to calculate customer use emissions

By Emma Watson
12th November 2020

This is the second blog in a three-part series on dealing with customer emissions. This series looks to answer three questions:

  • What are ‘use of sold products’ emissions?
  • How can we calculate consumer use emissions?
  • How can we reduce consumer emissions?

In part 1 we looked at understanding what ‘use of sold products’ emissions are. You can find this blog here.


Part 2: How to calculate customer use emissions

Dealing with customer use emissions is always tricky. In most cases, we can’t track what customers are doing at home and as a result this element of your carbon footprint is estimated.

As with all Scope 3 emissions calculations, we want to first understand where the material emissions lie. We can usually do this by doing some desk-based research.


What information will I need to get started?

The key piece of information needed to get started is to understand the number of products sold, and if possible, where those units were sold. The location where the goods are sold is especially important if the product consumes electricity. This is because these calculations incorporate national grid emissions factors.

Grid emission factors can vary greatly from country to country, as the fuels that are used to generate that power differ. For example, France’s emission factor of 0.0548 kgCO2e per kWh of electricity consumed is 76% lower than the UK’s grid emission factor of 0.23314 kgCO2e. As you might imagine, this can have a significant impact.

In some cases, it’s also important to know how many ‘uses’ a product will provide the customer over the product’s lifetime. We are currently working Ecover to calculate its Scope 3 footprint. We needed to know how many times each product would be used to understand total energy consumption.

For example, we typically use hot water when washing up dishes. Therefore, we also need to know how many washing up sessions we can get out of that bottle to understand the total energy used to heat water. This also highlights that the effectiveness of a product also has an impact on its carbon footprint – more uses per bottle means lower emissions.


Do your research

The next step is to start looking for research that has previously been conducted on products like the ones you sell. Useful information can usually be found by looking up Lifecycle Assessment studies (LCA). Typing in something like “washing up liquid lca” into Google will yield decent results.

Other sources of information include databases like Ecoinvent, which contains a plethora of information on life cycle emissions of products. There are also some sector-specific tools such as  Product Attributes to Impact Algorithm (PAIA) platform — a joint initiative of MIT and Quantis. This tool helps companies develop footprints for ICT hardware products.

You may also be lucky enough to have peers that are willing to share insights. Have a chat with them to see what they’ve used and if it might be helpful for you.

If you’re unable to find any useful information, conducting an LCA for your products using best practice standards such as ISO 14040 / 14044 with an external partner like Carbon Intelligence may be a good option. It’s important to apply best practice and leverage best available methods and standards so your calculations can stand up to scrutiny.


How can I make my calculations more specific?

Looking at what others have done is a great starting point to help you identify hotspots, but this may not show all the levers needed to pull to reduce emissions. We can tell from these calculations that a few factors are especially important:

  • The number of products sold
  • The longevity of the product
  • The number of ‘uses’
  • The energy consumed to power the product.

Within the first pass at calculating these emissions, it’s likely that some factors may not be specific to your company. For example, we may have estimated the energy that is consumed by looking at an LCA conducted for another company that sells an entirely different product.

Companies are starting to more fully understand the impact of these emissions so the maturity of calculations is evolving. There are a few options illustrated below that can improve your customer use calculations:



This process is slightly easier for products that directly consume energy, such as cars and computers. In these cases, companies can do their own tests to understand energy consumption to feed directly into their footprints. It’s important to note however that these tests may not be reflective of what happens in real life.

Another option is to work with your customers to understand how they use your products at home – for example, are your customers washing their laundry at 30.C? How many scoops of detergent do they use? Speaking to a select group of loyal customers may be a good option, but this may also introduce bias into the study that should be considered. Another option (in non-pandemic times!) might be to hold a focus group to understand habits and see how these might be influenced. This could of course be done virtually!

A final option is to use smart technologies to track consumer use. Software companies feed data back to developers on how the product is functioning, so this information could be used to understand energy consumption patterns as well. The Microsoft Sustainability Calculator allows their customers to analyse the emissions that arise from cloud workloads, which Microsoft will use to calculate its own footprint. There are important things to consider here around privacy so make sure legal teams are involved to understand what’s possible.


Calculating customer emissions is one piece on the puzzle, reducing those emissions the another. Controlling how customers use your products isn’t easy but there are many options for reducing these emissions. Keep an eye out for our next blog to read how in more detail.

Further resources

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If you would like to know more about how we’re helping our clients understand and reduce their Scope 3 emissions, contact us today at info@carbon.ci