Greenhouse Gas Inventory: What’s Under The Hood?


posted Dec 27, 2011, 11:56 AM by David J.

Greenhouse gas (GHG) emissions are one of the most widely accepted sustainability performance indicators of our time, making them of high interest to a wide variety of sectors. Many companies are interested in understanding the variation in GHG intensity from site to site. But how does a company collect that data?

We were hired to help a major food processing company investigate the energy-related GHG emissions throughout its supply-chain, to identify major risks opportunities for improvement.

There are multiple, well-established and increasingly-aligned protocols for measuring GHG: GHG Protocol, Climate Registry, Carbon Disclosure Project, ICLEI (for local governments). But the general process is pretty basic. The first step is to draw your boundaries: are we just looking at the owned properties, or also leased and/or substantially financed? And what about suppliers… and customers in their handling and use of the product? Which of these do we include?

Boundaries must be established for any reported metrics. For example, efforts like water footprinting expand the boundaries of water risks and inventorying beyond the traditional organizational borders.
For the food company, we decided to measure from the point-of-shipment of crops from the various countries through processing and transport to distribution centers, as these were the supply-chain stages where the company clearly had control, and where the data was relatively clear to inform their plan of action. We also included employee travel. One could extend the analysis down to the farm level, or out through customer use to landfill (compost) for the full picture. Extension of boundaries could actually lead to different implications when all is said and done.

That’s why selection of boundaries should be very intentional and linked with what you’re trying to achieve, not necessarily simply driven by the boundaries mandated by your particular reporting program (e.g. the protocols listed above). And boundaries, I’d argue, should be biased toward including more of the supply-chain to get a fuller picture (even if in this specific case we did not cover the entire supply-chain).

Next comes collection of data on GHG sources – miles traveled, gallons of fuel, kWh, therms of gas, etc. And, subsequently, application of conversion factors to put these various sources into their GHG equivalent (typically metric tons of CO2-equivalent). This gives you a number that represents your footprint (or inventory), given the assumptions and choices that were made.

We assumed that raw material shipping would be a huge part of the footprint. As it turned out, it was a significant contributor, but employee jet travel was nearly as significant (trips to Ethiopia and Brazil will rack it up!) Natural gas use in the production process was also large.

This type of analysis provides a clear delineation of which areas to focus on to make significant reduction. Analysis enables insight, which enables action.

(Originally posted at