Why Coffee's Environmental Footprint Depends on What You Count

Define the Cup Before Comparing It

The functional unit is the service being compared: the drink, its quantity and, where relevant, the number of servings over time. The system boundary identifies the stages counted. The US General Services Administration's glossary explains both terms.

For coffee, record beverage volume, dry coffee dose, any milk or other ingredients, and how often the drink is prepared. A small black espresso, a large milk drink and a shared filter batch provide different services. Our brewing methods guide helps identify the routine and equipment you want to compare.

A 2024 UK study by Gosalvitr and colleagues assessed coffee using three functional units: one serving, 1 L (33.8 US fl oz) of coffee and 100 mg of caffeine. Its rankings changed with the chosen unit. Each denominator asks a different consumption question.

Read the Study Boundary as Carefully as Its Result

The following two original studies show how the boundary changes what a result covers. Cibelli, Cimini and Moresi's 2021 paper examines a streamlined preparation system. Brommer, Stratmann and Quack's 2011 paper includes an appliance comparison as well as a separate whole-chain coffee case.

Converting both results to the same beverage volume would still leave different processes inside their boundaries. A useful comparison matches both the service and the stages counted.

Check Electricity, Timing and Disposal Assumptions

Energy use includes the pattern between servings as well as brewing. Check batch size, excess water heated, any cleaning cycles, standby operation and time on a warming plate. Then check which electricity supply the study uses to turn energy consumption into modeled emissions.

The 2011 appliance scenario includes long idle periods for machines without automatic power-down and a keep-warm period for a filter machine. The 2021 paper uses a specified multi-cycle measurement protocol, Italian electricity and an Italian waste-management scenario based on 2018 data. Match those conditions with the routine you actually follow.

For disposal, check which items your local collector or return program accepts, and how they must be separated. The filter guide and pod coffee guide help identify the products; the accepted collection route determines what happens after use.

A sensitivity analysis changes an assumption to see how much the result moves. It can show whether a comparison depends strongly on standby time, disposal or another part of the modeled routine.

Count What Is Consumed, Not Only What Is Brewed

Here is a hypothetical batch, with all amounts referring to finished beverage:

The discarded share is 150 ÷ 600 = 25%. The household brewed 600 ÷ 450 = 1.33 mL for each milliliter consumed. This suggests checking whether a better-sized batch would meet the same drinking need.

The 25% describes discarded volume, not a matching reduction in total emissions: appliance production, heating and other inputs may change differently. The one-week coffee waste diary helps measure your own leftovers before choosing a change.

Record dry coffee dose, wet grounds and leftover beverage separately. Wet grounds contain retained water, so adding their wet mass to the original dry dose would double-count coffee input and include water as coffee waste.

Choose a Change That Fits the Comparison

Before using a result, check four things:

• Does its drink and serving pattern resemble yours?
• Which life-cycle stages and impact categories does it count?
• Are its country, electricity supply, data year, heating pattern and disposal route relevant?
• Does the conclusion hold when the important assumptions change?

A carbon footprint addresses climate-related emissions. Other impact categories cover questions such as resource use, water-related impacts and pollution. Use the category that answers the decision you are making.

For a household routine, the practical opportunities are recognizable: better match the batch to what people drink, end an unnecessary warming period, and use an accepted disposal route. Their benefit depends on the inputs they change, rather than the name of the brewing method alone.

A personal note: I want an environmental comparison to help with a decision I can recognize in my own routine. Before giving much weight to its ranking, I am interested in the serving it describes and the stages it counts. A result about one small black coffee asks a different question from a household's larger batch with leftovers. I find those details useful because they show where the reasoning fits. I do not need to calculate a personal footprint to learn from the comparison. I need to understand the example well enough to know which parts can inform my choices.

Sources

• US General Services Administration: Life cycle assessment key terms
• Cibelli, Cimini and Moresi (2021). Carbon Footprint of Different Coffee Brewing Methods. Chemical Engineering Transactions 87, 373–378. DOI: 10.3303/CET2187063
• Brommer, Stratmann and Quack (2011). Environmental impacts of different methods of coffee preparation. International Journal of Consumer Studies 35, 212–220. DOI: 10.1111/j.1470-6431.2010.00971.x
• Gosalvitr, Cuéllar-Franca, Smith and Azapagic (2024). Environmental and economic sustainability assessment of the production and consumption of different types of coffee in the UK. Sustainable Production and Consumption 49, 144–162. DOI: 10.1016/j.spc.2024.06.004

Related Reading

• Compostable or Recyclable Coffee Packaging: Check the Destination
• A One-Week Coffee Waste Diary: Measure Before Changing Your Setup