If a general contractor, a public owner or your own board asks for your fleet’s emissions, the answer starts with fuel. For off-road diesel equipment, Scope 1 CO2 is gallons times a published factor, so the real work is getting the gallons right.
What Scope 1 covers
The Greenhouse Gas Protocol splits emissions into three scopes. For an equipment fleet:
- Scope 1 is direct emissions from fuel burned in sources you own or control: excavators, loaders, dozers, haul trucks, pickups, generators, light towers and heaters.
- Scope 2 is purchased electricity: the shop, the yard lights and the chargers for any electric machines.
- Scope 3 is the rest of the value chain, including your subcontractors’ fuel when you are the general contractor.
Rented machines depend on your reporting boundary. Under the operational control approach, fuel you buy and burn in a rented machine you operate generally counts in your Scope 1. Confirm the boundary with whoever prepares or receives your report, and write the decision down so next year’s report uses the same one.
The core formula
The EPA’s GHG Emission Factors Hub lists 10.21 kilograms of CO2 per gallon of diesel fuel. That turns gallons into carbon dioxide with one multiplication.
Metric tons of CO2 = gallons of diesel × 10.21 ÷ 1,000
Worked example. A 30-machine contractor burned 120,000 gallons of diesel last year across its machines, trucks and generators.
- 120,000 gallons × 10.21 kg = 1,225,200 kg of CO2
- 1,225,200 kg ÷ 1,000 = 1,225.2 metric tons of CO2
One excavator in that fleet that burned 6,000 gallons accounts for 6,000 × 10.21 ÷ 1,000 = 61.26 metric tons.
Three cautions keep the math honest:
- Metric tons. A metric ton is 1,000 kilograms, about 2,205 pounds. It is not the 2,000-pound short ton.
- Other gases. The Hub also lists methane and nitrous oxide factors by equipment type. If your report asks for CO2 equivalent rather than CO2, add those using the Hub’s factors and the warming potentials your reporting standard names.
- Other fuels. Gasoline in pickups and propane in forklifts or heaters use their own factors from the same Hub.
Where the gallons come from
Your answer is only as good as your fuel records. From most to least reliable at the machine level:
- Fuel truck logs by machine. Each delivery recorded against the machine number with a meter reading.
- Engine-reported fuel use. Fuel used, read from the engine controller or a manufacturer feed.
- Fuel cards and receipts. Good for pickups and trucks that fuel at stations.
- Bulk deliveries. Supplier invoices for the yard tank or job tanks. Accurate in total, silent about which machine.
- Hours times burn rate. An estimate, for machines with no other record. Label it as one.
Bulk deliveries anchor the total. Machine-level records tell you where the fuel went.
Unallocated fuel = bulk gallons delivered minus gallons assigned to machines
Worked example. In March a yard tank near Hobbs received 10,000 gallons. The fuel truck log assigns 9,200 gallons to machines, which leaves 800 gallons unallocated. Before you report, find out why: untagged pickups, a meter out of calibration, spillage, or fuel walking off the lease. A common approach is to report the delivered total and note how much could not be assigned. Agree the method with whoever receives the report.
Allocate emissions to jobs
Owners and general contractors often want emissions per project, not per company. Once each machine’s fuel is tied to the job it worked on, the same formula applies.
Job CO2 (metric tons) = gallons burned by machines on the job × 10.21 ÷ 1,000
Worked example. A road job near Las Cruces used four machines last quarter inside the job geofence:
| Machine | Gallons on the job | Metric tons of CO2 |
|---|---|---|
| Excavator | 2,000 | 20.42 |
| Wheel loader | 2,000 | 20.42 |
| Motor grader | 1,000 | 10.21 |
| Water truck | 1,000 | 10.21 |
| Total | 6,000 | 61.26 |
A machine that worked two jobs in the quarter splits its fuel by the engine hours it logged inside each job’s geofence. A machine that fueled at the yard and worked on the job still counts on the job.
Pick one intensity measure your customers ask for, such as metric tons per engine hour, per thousand cubic yards moved or per lane mile, and keep it the same from year to year. A number that changes definition every year can’t show progress.
Close the fuel books monthly
Emissions reports go wrong when the fuel data is assembled once a year from invoices nobody has looked at since spring. A short monthly routine is easier and more accurate.
- Collect deliveries. Every bulk fuel invoice for the month, by tank and fuel type.
- Collect machine records. Fuel truck logs, engine-reported fuel use and fuel card statements.
- Reconcile. Compare the two and work out the unallocated gallons while people still remember the month.
- Assign to jobs. Use each machine’s hours inside each job geofence.
- Convert. Run the formula and store the month’s result with its inputs.
- Note changes. New machines, sold machines, a new tank, a meter replaced.
Twelve monthly closes add up to the annual report, with the reasons already written down.
Answer a customer questionnaire
When a general contractor or a public owner sends an emissions questionnaire for a project, most of what they want fits in a short answer:
- gallons of each fuel burned on their project, for the period they name
- metric tons of CO2, or CO2 equivalent if they ask for it
- the factor source and edition, such as the EPA Hub figure of 10.21 kilograms per gallon of diesel
- how fuel was assigned to the project: fuel logs, engine data or estimates
- what is included and excluded, such as pickups, generators or subcontractors
Send the method with the number. A figure with its method attached raises fewer follow-up questions than a bare total.
Cutting emissions means cutting fuel
For diesel equipment, CO2 moves in lockstep with gallons. Every gallon not burned is 10.21 kilograms not emitted, so the fuel levers are the emissions levers:
- Idle. The cheapest gallon to save is the one burned standing still. Our note on what idle time really costs works through the math.
- Hauling. Fewer empty lowboy miles and fewer service truck trips.
- Right-sizing. A smaller machine where a smaller machine will do.
- Maintenance. Clean air filters, and correct tire pressure on trucks and loaders.
- Electric compacts, where the duty cycle and the plug allow.
Worked example. A 30-machine fleet cuts one idle hour per machine per working day, at 1 gallon an hour, over 200 working days. That saves 6,000 gallons, which is 61.26 metric tons of CO2 and, at $4 a gallon, $24,000. The ROI calculator lets you test the same idea with your own idle hours and fuel price.
Hauling is easy to miss, because it hides in trucks rather than machines. The fleet logistics service treats dispatch, hauling and fuel as one chain, so a move planned with a backhaul saves fuel on the truck and shows up in the same report.
A reporting checklist
- Boundary decided: owned, leased and rented equipment, and subcontractors
- Reporting period and every fuel type listed
- Each data source named, with its quality
- Factor source and the Hub edition you used
- Unit conversions shown, with metric tons stated
- Bulk deliveries reconciled against machine records
- Estimates labeled as estimates
- The calculation saved so someone else can repeat it next year
- A reviewer who wasn’t the preparer
Reporting requirements vary by customer, owner and jurisdiction. Confirm exactly what is being asked with whoever requested it, and check with your own adviser where a regulation applies.
Mistakes in fleet emissions math
- Short tons. Reporting short tons where metric tons were asked for, or mixing the two in one table.
- Double counting. Fuel counted once when delivered to a job tank and again when dispensed to machines.
- Missing sources. Generators, light towers, heaters and pickups left out.
- Silent estimates. Hours times burn rate presented as measured fuel.
- Old factors. A factor from an earlier Hub edition used without noting the year.
- Wrong fuel. The diesel factor applied to gasoline, or the reverse.
- No paper trail. A total with no record of how it was built, which nobody can defend when asked.
Report fuel by machine and job
Fuel and emissions ties each gallon to the machine and the job that burned it, and produces fuel and emissions reports by machine and by job. It is on the Command plan, inside fleet logistics beside dispatch and haul planning, because hauling and fueling are planned together.
