Our construction industry page covers who asks builders for carbon figures and every source in a contractor's footprint. This post goes into the part that is hardest to get right and often the biggest: fuel burned on site by generators and plant.
Who owns which emissions on a site
On the operational control basis, the simplest for a contractor, you count the emissions from equipment you run, whoever owns it. On a typical site that sorts out like this:
| What's burning fuel | Whose Scope 1 | In your footprint as |
|---|---|---|
| Your own generators, excavators, dumpers and telehandlers | Yours | Scope 1 |
| Dry-hired plant your operators run and you fuel | Yours | Scope 1 |
| Plant hired with an operator, run by the hire company | Normally the hire company's | Scope 3, category 1 (a purchased service) |
| A subcontractor's own plant and generators | The subcontractor's | Scope 3, category 1 |
| A temporary grid supply on a site you run | Not Scope 1 | Scope 2 (electricity) |
The GHG Protocol's guidance on leased assets is the basis for the dry hire rule: a lessee with operational control reports the fuel burned as Scope 1. Wet hire is less clear cut, because you may still pay for the fuel. If the hire company runs the machine, the cleaner reading is that it is their emission; whichever you choose, write it in your method note and apply it the same way every year.
Where the litres come from
- Fuel delivery tickets and invoices for bowsers and site tanks. The most reliable source, because it is what you paid for.
- Fuel cards for plant filled at a forecourt or by jerry can.
- Hire company fuel recharges, when dry-hired plant comes back below full and they bill you for the difference.
- Telematics on newer plant, which reports litres burned and hours idling. Useful for checking the invoices and for finding savings.
Use litres where you have them. Plant hours multiplied by an assumed burn rate is a last resort, and if you use it, say so in your method note.
Which factor: diesel or gas oil?
Since 1 April 2022 most construction plant can't use red diesel, which the government restricted to uses such as agriculture, rail, and heating and power in non-commercial premises. Plant on a building site now generally runs on full-duty diesel, which takes the diesel factor: 2.58354 kg CO2e per litre in 2026. If your invoices say gas oil, use the gas oil factor instead, 2.75541 kg CO2e per litre. Pick the factor from what the invoice says you bought, not from what the machine is.
If you have switched plant to HVO, use the factor for HVO rather than diesel. Our post on HVO and Scope 1 explains how it is reported and why the biogenic CO2 is reported separately.
A worked example
A contractor runs one site for 40 weeks, with a diesel generator for the cabins and dry-hired plant its own operators drive:
| Source | Litres | kg CO2e |
|---|---|---|
| Generator, 150 litres a week | 6,000 | 15,501 |
| Dry-hired excavator and telehandler | 8,000 | 20,668 |
| Total, Scope 1 | 14,000 | 36,170 kg, or 36.17 tonnes |
Cutting fuel use by a tenth, for example by switching plant off instead of idling, would save about 3.62 tonnes on this site alone, and the same share of the fuel bill.
Generator or grid?
Diesel holds about 0.2452 kg CO2e for every kWh of energy in the fuel. A generator only turns part of that energy into electricity, so each kWh it produces carries more than that, against 0.13096 kg CO2e for a kWh from the grid in 2026. Even a perfect generator would be about 1.9 times the grid figure. That is why an early grid connection, or a battery hybrid generator that lets the engine stop when demand is low, is worth pricing up on any site where the generator runs for months.
Don't forget the skips
Site waste goes in Scope 3 category 5, which a PPN 006 plan includes. Segregation makes a real difference: in 2026 a tonne of wood sent to landfill is 925 kg CO2e, against 5 kg recycled. In England, construction sites must also keep dry recyclables and food waste separate from construction waste under the Simpler Recycling rules, so the collection records should already exist. Our post on using waste contractor data shows how to turn transfer notes into figures.
How Carbon Recycling helps
Add each site in Carbon Recycling and tag fuel deliveries, fuel cards, temporary supplies and skips to it, or upload them in bulk with the company vehicles and energy CSV templates. Every line gets the right year's DESNZ factor, diesel and gas oil kept apart, and each site gets its own report, so you can show a client the figures for their job while your Carbon Reduction Plan stays at company level. Try your own fuel figures first in the free CO2e calculator. For the wider picture of reporting as a supplier to main contractors, see our post on supplier carbon data requests.