Customer Wants Carbon Footprint: What Suppliers Need to Know
The request might come as a single line in an email: "Please provide your carbon footprint data for our annual reporting." Or it might arrive as a detailed questionnaire asking for emissions broken down by category, methodology documentation, and third-party verification status.
Either way, you're being asked for numbers you've probably never calculated. Most suppliers haven't. Carbon footprint tracking has historically been the domain of large corporations with sustainability departments and consultant budgets. Now it's cascading down to suppliers of every size.
Here's what customers actually need, what you can realistically provide, and how to approach this even if you've never thought about emissions data before.
What "Carbon Footprint" Means in Practice
When customers ask for your carbon footprint, they're asking how much greenhouse gas your operations emit. The standard unit is tonnes of CO2 equivalent (tCO2e), which converts different greenhouse gases (methane, nitrous oxide, etc.) into a common measure based on their warming potential.
The scope of what they want varies:
Organizational footprint: Total emissions from your entire company's operations for a year. This is the most common request.
Product footprint: Emissions associated specifically with producing the products you supply to this customer. More complex, requires allocation of your operations to specific products.
Scope-specific: Some customers specifically want Scope 1 and 2 only (your direct operations), while others also want Scope 3 (your supply chain's emissions).
If the request isn't clear about scope, ask. A five-minute clarification email saves hours of calculating things they didn't actually need.
The Three Scopes Explained Simply
Scope 1: Direct emissions you control
Anything you burn on-site or in vehicles you own: natural gas for heating, diesel in company trucks, propane for forklifts, refrigerant leaks from cooling systems. If fuel combusts at your facility or in your fleet, it's Scope 1.
Scope 2: Indirect emissions from purchased energy
Electricity is the big one. You buy power from the grid; someone generated that power and emitted carbon doing so. Those emissions count as your Scope 2. Purchased steam, heating, or cooling from external sources also fall here.
Scope 3: Everything else in your value chain
This is the expansive category: emissions from making the materials you purchase, transporting goods to you, employee commuting, business travel, waste disposal, product use by customers, and eventual disposal. Scope 3 typically represents 70-90% of a company's total footprint but is the hardest to calculate.
Most customers asking suppliers for carbon data want at least Scope 1 and 2. Whether they need Scope 3 from you depends on their reporting requirements and sophistication.
Calculating Your Scope 1 and 2
These are straightforward if you approach them methodically.
Gather activity data for 12 months:
For Scope 1, collect:
- Natural gas bills (in kWh, therms, or cubic meters)
- Vehicle fuel purchases (liters or gallons of diesel, petrol)
- Any other fuel combustion (heating oil, propane, etc.)
- Refrigerant recharge records if you have cooling systems
For Scope 2, collect:
- Electricity bills (kWh consumed)
- Any purchased steam or district heating
Apply emission factors:
Emission factors convert activity (kWh of electricity) into emissions (kg CO2e). Published factors are available from:
- UK DEFRA (comprehensive, widely accepted internationally)
- US EPA (for American operations)
- Your national environment agency
- IEA for electricity grid factors by country
For example: 10,000 liters of diesel × 2.68 kg CO2e per liter = 26.8 tonnes CO2e
Sum everything up:
Add all Scope 1 sources together. Add all Scope 2 sources together. You now have your organizational carbon footprint for Scope 1+2.
The math is arithmetic. The work is gathering the underlying data. If your energy bills are organized, you can calculate Scope 1+2 in an afternoon.
When Customers Want Product-Level Carbon
Some customers need emissions allocated to specific products rather than company totals. This is more complex because you need to decide how to attribute your operational emissions to different outputs.
Common allocation approaches:
By revenue: If Product A represents 30% of your revenue from this customer, allocate 30% of your emissions.
By production volume: If Product A is 30% of units produced, allocate 30% of emissions.
By production time: If Product A uses 30% of machine hours, allocate 30% of emissions.
No approach is perfect. Pick one that makes sense for your operations and be transparent about your methodology. Customers care more about consistency and transparency than which specific method you choose.
What If You've Never Tracked This?
Most suppliers haven't. This isn't a crisis; it's a starting point.
Can you produce numbers now? Yes. Go find your last 12 months of energy bills. That's enough to calculate Scope 1+2 with acceptable accuracy for most customer requests.
Will the numbers be perfect? No. You might miss some minor sources. Your fuel records might have gaps. That's normal for first-time calculations.
Should you estimate missing data? Yes, with transparency. If you're missing two months of electricity data, extrapolate from the months you have. Note the estimation in your response.
What about Scope 3? For a first-time response, you can reasonably state: "Scope 3 calculation is in development. We are providing Scope 1 and 2 data at this time." Most customers understand that supplier Scope 3 reporting takes time to establish.
The article on responding when you don't have everything covers specific strategies for handling data gaps professionally.
Presenting Your Carbon Data
When responding to customers, include:
The headline number: Total emissions in tCO2e for the reporting period.
Breakdown by scope: Scope 1 and Scope 2 separately, at minimum.
Reporting period: Which 12 months this covers (calendar year, fiscal year, or other).
Methodology notes: What emission factors you used, what's included/excluded, what's estimated versus measured.
Boundary definition: What operations are covered—all facilities? Just those serving this customer?
Data quality statement: Honest acknowledgment of limitations.
A simple table works well:
| Category | Emissions (tCO2e) | Notes | |----------|-------------------|-------| | Scope 1 | 45.2 | Natural gas + fleet fuel | | Scope 2 | 112.8 | Purchased electricity | | Total | 158.0 | Calendar year 2024 |
This is scannable, clear, and professional. Customers reviewing dozens of supplier responses appreciate simplicity.
Intensity Metrics Customers May Request
Beyond absolute emissions, customers often want intensity metrics that normalize for business size:
Per unit of production: 0.5 kg CO2e per widget
Per revenue: 12 tonnes CO2e per €1 million revenue
Per employee: 3.2 tonnes CO2e per FTE
These help customers compare suppliers of different sizes and track efficiency improvements over time. If you're reducing emissions while growing production, your absolute number goes up but your intensity improves.
If a customer doesn't specify which metrics they need, provide both absolute numbers and at least one relevant intensity metric.
Getting Ready for Next Year
Once you've responded to your first carbon footprint request, set yourself up for easier annual updates:
Track energy monthly. A simple spreadsheet logging each month's electricity, gas, and fuel consumption turns the annual calculation into a five-minute sum rather than a half-day document hunt.
Save your methodology. Document which emission factors you used and why. Consistency year-over-year matters more than perfection in any single year.
Note improvement opportunities. Customers increasingly ask about reduction targets and progress. If your calculation reveals that 60% of emissions come from electricity, that's where efficiency investments have the most impact.
Keep response copies. You'll get similar requests from other customers. Having last year's response as a template accelerates future work.
The Business Case for Carbon Tracking
Beyond responding to customer requests, knowing your carbon footprint has practical benefits:
Energy costs and carbon emissions are directly correlated. Reducing emissions usually means reducing energy costs. The efficiency opportunities you identify for carbon purposes often pay for themselves financially.
Some customers are beginning to factor carbon intensity into procurement decisions. Lower-emission suppliers may win business on that basis, or at least won't lose it.
Regulatory requirements are expanding. Even if you're not directly subject to CSRD today, tracking emissions positions you for whatever comes next.
The suppliers who start tracking now—even imperfectly—build capability that compounds. Those who wait until forced will scramble under deadline pressure, exactly like they're scrambling today with ESG questionnaires.
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