How wrong is your Scope 2 number?
Most Australian commercial Scope 2 reports rely on an annual-average grid factor from DCCEEW. It’s the legally defensible default. It’s also, depending on when you operate, meaningfully wrong.
Below is a full worked example for an illustrative Australian commercial site. The intensity and consumption figures are representative, not a specific historical day, but the arithmetic is the same arithmetic gridIQ performs on actual meter data against actual half-hourly carbon intensity.
The illustrative site
An 8.6 MWh/day facility in New South Wales. Operations start at 06:00 and wind down after 22:00. Overnight load is minimal. 250 operating days per year. Annual consumption: 2,150 MWh.
Method 1: location-based
Use a single annual-average grid intensity factor. For this worked example we use 0.68 tCO₂/MWh, which sits in the range of recent DCCEEW NSW factors (use the factor current at the time of your reporting period in practice).
This is the number that lands in most sustainability reports today. It’s fast to calculate and easy to defend. It’s also blind to when the site actually consumed.
Method 2: time-matched location-based
Break the day into windows, match each window to the grid’s actual carbon intensity while consumption happened, then re-aggregate. A representative day for this site looks like:
| Window | MWh | Intensity (tCO₂/MWh) | Emissions (tCO₂) | Note |
|---|---|---|---|---|
| 00:00–06:00 | 0.5 | 0.72 | 0.36 | Overnight baseload, higher intensity |
| 06:00–10:00 | 1.8 | 0.55 | 0.99 | Morning ramp, solar rising |
| 10:00–14:00 | 2.4 | 0.32 | 0.77 | Solar peak, renewables dominant |
| 14:00–18:00 | 2.0 | 0.48 | 0.96 | Solar fade, gas ramp |
| 18:00–22:00 | 1.3 | 0.71 | 0.92 | Evening peak, coal and gas |
| 22:00–24:00 | 0.6 | 0.70 | 0.42 | Late evening, coal baseload |
| Day total | 8.6 | 0.514 (wtd) | 4.42 |
Weighted daily intensity is 0.514 tCO₂/MWh , lower than the annual average because the site runs heavily during solar hours and barely operates overnight when the grid intensity is higher.
The delta
For this illustrative daytime-weighted load, time-matching cuts reported emissions by roughly 24%. Flip the consumption profile to overnight-heavy and the delta flips too: time-matched emissions can come in higher than the location-based figure when load sits on coal baseload while the sun is down.
Which number is right?
Both figures are legitimate under the GHG Protocol. The location-based figure is the baseline all entities must report, and time-matching it to the grid intensity when you actually consumed shows your true exposure rather than an annual smear. The market-based figure is a separate calculation, substantiated by EAC instruments or a PPA, where a contracted clean-supply claim lives. Under Australia’s emerging ASRS regime, assurance teams will increasingly expect both methods.
The trap is reporting only the annual figure when your operations genuinely run during lower-emission-intensity periods than the annual average. You under-claim your emissions performance. The opposite trap, leaning on a flattering time-matched figure when your load sits on higher-intensity overnight periods, overstates it. Australia’s mandatory climate reporting from 2026 expects both location-based and market-based methods, and a market-based figure must be substantiated by instruments. Report both. Let the audit trail show the work.
Where the data sits in gridIQ
Feed gridIQ your half-hourly meter data. It matches each interval to the grid carbon intensity calculated from the actual generation mix at that moment, stamps the DCCEEW factor version current during your reporting period, and returns both methods side by side with a full audit trail. Re-run the same period next year and you get the same numbers. The factor vintage stays locked to when you reported, not silently re-baselined as DCCEEW publishes updates.
Getting started
Every gridIQ account includes a 21-day Pro trial with full access to the Scope 2 emissions tracker. Upload a NEM12 meter file to get both the annual-average and time-matched location-based Scope 2 Australia calculations side by side, with an audit trail ready for mandatory climate reporting Australia 2026. Create your account to get started.
Illustrative worked example. Intensity values and the location-based factor are representative of Australian NEM conditions but do not reflect a specific historical day or a specific customer. Use the DCCEEW factor current to your reporting period for defensible disclosure.