Does laying bitumen or hot mix asphalt cause direct greenhouse gas emissions of its own, according to the Intergovernmental Panel on Climate Change (IPCC)?
The IPCC calls direct greenhouse gas emissions from making and laying asphalt negligible: much less than one percent of the carbon is emitted, and the rest stays in the product. What counts is the fuel burnt to heat, mix and haul it, plus the bitumen's upstream footprint. Cutback grades release diluent vapours.
What the Guidelines say
Volume 3 Chapter 5, Section 5.4: asphalt production and use mainly emits non-methane volatile organic compounds (NMVOC), carbon monoxide (CO), sulphur dioxide (SO2) and particulate matter, while the remaining hydrocarbons are "stored in the product (much less than one per cent of the carbon is emitted)". Direct emissions of carbon dioxide (CO2) or methane "are negligible since the majority of the light hydrocarbon compounds were extracted during the refining process" Recycled asphalt pavement used as aggregate is also negligible.
Fuel burnt "to supply heat to the asphalt processes (production or heating of the asphalt mix)" is covered under the Energy sector, not here. Limestone in the aggregate: "no CO2 is assumed to be released in the heating process".
Which grades emit more
- Hot mix asphalt is "by far the most widely used, generally over 80 percent, and produces very few emissions".
- Cutback asphalt is thinned with petroleum diluents such as heavy residual oils, kerosene or naphtha solvents, so it shows "a relatively high level of emissions of CO and NMVOC due to the evaporation of the diluent". Rapid-cure uses a naphtha or gasoline-type diluent, medium-cure a medium-volatility one, slow-cure oils of low volatility.
- Emulsified asphalt contains mostly water and little or no solvent.
- Blowing asphalt with air for roofing gives the highest NMVOC and CO emissions of the process steps.
Getting bitumen tonnes when you only know the area
If only the area paved is known, the Guidelines say a conversion factor of 100 kilograms of asphalt per square metre of road surface may be used. Hot mix "typically contains about 8 percent asphalt cement (bitumen)... but this may differ between countries (a figure of 5 percent has also been reported)". Use your delivery tickets or mix design where you have them.
So where do the road emissions come from
Our reading: from the diesel and fuel oil or gas for the dryer drum, the paver, roller and haulage, and from the bitumen and aggregate you buy, as our road pages show. The IPCC counts by sector and does not use Scopes.
Bitumen in 10,000 square metres of new road surface
- Asphalt: 10,000 x 100 kilograms = 1,000,000 kilograms, which is 1,000 tonnes
- Bitumen at 8 percent: 1,000 x 0.08 = 80 tonnes
- Bitumen at 5 percent: 1,000 x 0.05 = 50 tonnes
- Direct carbon dioxide from the laying itself: treated as negligible by the Guidelines, so no line is added
The area is an example. The 100 kilograms per square metre is the Guidelines' conversion for when only the area is known; your own mix tickets are better.
What Senseible does here
Senseible reads fuel invoices and electricity bills into dated records, so the plant fuel and the paver and haulage diesel show up once uploaded. It does not read bitumen delivery tickets, so keep the tonnes in your own sheet.
Sources: IPCC 2006 Guidelines, Volume 3 Chapter 5 (Section 5.4, Box 5.1)
Last reviewed 2026-11-05. Statements are from the 2006 Guidelines. The upstream footprint of bitumen is a separate figure from your supplier or a named database.