Curious How GHG Protocol Scope 2 Accounting Changes Might Impact Your Reporting? This New Calculator Can Help.

There are times when an obscure or otherwise esoteric change in business policy or operations can result in surprisingly outsized impacts.

In the late 1980s, American Airlines removed a single olive from each salad served to passengers in first class as a cost-cutting measure. The move saved the company $40,000 annually (around $100,000 in today’s dollars). A decade earlier, shipping company UPS instituted a “no left turn” policy that it later codified in 2004 in its routing software. In the process, the company is saving an estimated 10 million gallons of fuel and 20,000 tonnes of carbon emissions annually, while delivering 350,000 more packages.

Now, voluntary corporate clean energy procurement is poised for a similarly big “butterfly effect.” But this time, the likely end result is higher cost, greater carbon emissions, and increased administrative complexity.

Scope 2 at a fork in the road

The would-be driving force is proposed changes to the GHG Protocol’s rules for Scope 2 carbon accounting, used by 92% of Fortune 500 and 97% of disclosing S&P 500 companies. Whether those rule changes go into effect remains to be seen. A public comment period is currently open (through an extended deadline of January 31, 2026), and any Scope 2 revisions wouldn’t go live until 2027.

But make no mistake: change is a-comin’ to Scope 2 carbon accounting. One way or another, business as usual will be out the window. And however things shake out, it will mean important changes to companies’ clean energy purchasing strategies and reported emissions calculations.

Scope 2 reporting under GHGP’s Market-Based Method (MBM) is at a pivotal fork in the road between two very different approaches. The details have been covered pretty widely in trade media (including Heatmap earlier this fall), organization blog posts, and professional social media, so we’ll just summarize the basics here:

1. Hourly matching: GHGP has put this forward as the proposed new requirement. Organizations would only be allowed to count procured clean energy or certificates toward their Scope 2 emissions calculations if they are a) produced in the same hour as their electricity demand and b) located within the same grid region as their load.

2. Impact accounting: GHGP is also soliciting input on a voluntary consequential accounting standard. Such impact accounting separately calculates the induced emissions of an organization’s electricity consumption and the avoided emissions of its clean energy purchases. This encourages procuring clean energy from locations that would avoid the greatest emissions globally.

Both approaches represent changes from today’s status quo, but with very different effects on reported emissions and clean energy procurement strategies.

Making sense of what it means for your organization

If you’re feeling like you’re left scratching your head about how Scope 2 accounting changes would actually impact your company, you’re not alone. It’s a lot to parse. And it’s not immediately apparent how the proverbial rubber would meet the road with proposed changes and their effect on companies’ Scope 2 calculations.

To help bridge that abyss, WattTime and REsurety have launched a free, public Scope 2 accounting calculator. It allows any organization to input its own information and then compare/contrast the outcomes under hourly matching vs. impact accounting approaches. Here’s how it works:

• Load sources: First, add info about your various current and/or future load sources, including their grid region location, annual electricity consumption, standard supply service (SSS), and choose from a set of common building load profiles that most closely match your facilities.
• Generation sources: Next, add info about your current and/or future clean energy purchases, including the grid region, generation type (wind or solar), purchasing instrument (VPPA or EACs), and annual electricity generation.
• Review results: Finally, review the calculated results for your organization. You’ll be able to compare reported emissions, procurement costs, and other outcomes under both hourly matching and impact accounting approaches.

Understanding a common scenario

To get a sense for the calculator tool and the two carbon accounting approaches, the team at REsurety also used the calculator to run the numbers for an illustrative mock company, CleanCo.

Like many organizations that voluntarily report under the GHGP, CleanCo has operations and electricity load across multiple grid regions in the US and Europe. They also procure clean energy from a variety of grid regions, but the overlap with the grid regions of their facilities isn't perfect. However, they do procure enough clean energy to meet 100% of their demand on an annual basis.

For CleanCo, the Scope 2 calculator results were eye-catching.

Only 50% of CleanCo’s current clean power procurement counts in hourly matching. Getting back towards its original 100% clean energy match would either incur significant additional costs to procure additional qualifying clean energy, or CleanCo would need to “fill the gap” with unbundled RECs that would likely have no additional impact — all in grid regions with lower carbon abatement potential. Meanwhile, if CleanCo shifted to a clean energy procurement strategy based on an impact accounting approach, it could avoid 4x more emissions at less than half the cost.

But that’s hypothetical CleanCo. The Scope 2 calculator is designed for real-world corporate sustainability and energy procurement professionals. Run the numbers for yourself and for your company. Then go and tell the GHGP how you feel about the possible outcomes. Because, like an American Airlines olive or a UPS right-turn only, the forthcoming changes to GHGP’s Scope 2 rules are going to have big ripple effects — this time on companies’ reported carbon emissions and clean energy procurement strategies. Make sure your voice is part of that process.