Practical framework / 5 MIN READ
Compare emissions estimates with the same scope and assumptions
Inspect what the calculator includes before ranking media plans by carbon.
AI-assisted research and analysis for the SNS Creative Fieldbook
Sources checked 2026-11-06
Two media-emissions estimates can differ because their methods cover different activities, use different proxy data or allocate shared infrastructure differently. A useful comparison makes those choices visible before turning a modeled number into a procurement preference.
What you will leave with: Build an emissions comparison sheet with boundaries, inputs, uncertainty and a decision-use statement.
Use this when
- Two providers report very different carbon estimates for similar campaigns.
- A media plan is being ranked by emissions intensity without disclosing the calculation.
This is methodological review, not carbon-accounting certification or permission to make environmental advertising claims.
Define the comparison’s functional unit
State whether the estimate concerns the whole campaign, a thousand delivered impressions, a completed video or another unit. Preserve total emissions alongside intensity. A lower per-impression estimate can coexist with higher total emissions if the plan buys substantially more impressions.
Check that the options serve a comparable business purpose and audience context. A low-emissions plan that cannot reach the required audience is not an equivalent replacement. Keep effectiveness evidence separate from environmental estimates rather than hiding one inside an unexplained composite score.
Map the included activities and methodology version
Ad Net Zero’s digital implementation guide describes modeled emissions components and scope boundaries. It also cautions that a lower calculated estimate need not represent an actual reduction in real-world emissions. Use the framework to ask specific methodological questions, not as a blanket endorsement of every calculator.
Record whether the estimate covers production, ad selection, transfer, device usage, embodied equipment emissions and allocated overhead, as relevant to the chosen method. Mark exclusions and placeholders explicitly. Compare the same methodology version or document why a version change makes a trend unsuitable.
Inspect inputs, proxies and uncertainty
Ask which activity inputs are measured, supplier-reported, modeled or defaulted. Review geography, energy assumptions, file size, delivery volume and allocation rules where they materially affect the result. A long decimal number does not compensate for a coarse proxy.
Request a sensitivity analysis for the most influential uncertain inputs. Do not demand confidential technical detail beyond the agreed review rights, but treat unexplained assumptions as a limitation on decision use. Check for double counting when combining supplier totals and for omitted stages when stitching together partial estimates.
Use the estimate for a bounded improvement decision
Identify changes that plausibly reduce the relevant activity, such as avoiding unnecessary delivery or reducing an excessive asset payload without harming usability. Evaluate the operational and effectiveness consequences separately. Do not infer physical emissions savings solely from switching a modeling category to one with a lower factor.
Preserve the baseline, method and changed inputs so future comparisons are interpretable. Have qualified sustainability and legal owners review any public claim. Internally, state whether the evidence supports directional planning, a comparative estimate or a verified reduction; these are different levels of confidence and consequence.
Make the reasoning concrete.
A hypothetical calculator reports 100 kilograms of CO2e for Plan A and 80 for Plan B. Plan A includes device-use emissions while Plan B omits them. The apparent 20-kilogram advantage is not a like-for-like finding, and neither modeled total alone proves an actual emissions reduction.
Rank the headline totals
Opening: Select Plan B because 80 is smaller than 100.
Hypothesis: The numerical comparison is simple.
Risk: Different scope can create an artificial advantage.
Align the methods
Opening: Reconcile included activities and inspect key assumptions before comparing.
Hypothesis: The team can see whether any difference survives a common scope.
Risk: Residual uncertainty may prevent a precise ranking.
Withhold a comparative carbon claim until the boundaries are aligned. Use a transparent, qualified estimate for planning and obtain specialist review for consequential claims.
Take the questions into your next brief.
Use these prompts in your own notes. Nothing is submitted from this page.
Unit
What activity and total campaign are compared?
Boundary
Which lifecycle stages and overheads are included?
Inputs
Which values are measured and which are proxies?
Sensitivity
What assumptions could reverse the ranking?
Use
Does the evidence support planning, comparison or verified reduction?
Watch for the wrong conclusion.
- Comparing different lifecycle scopes.
- Reporting intensity while hiding total growth.
- Treating a lower model factor as a physical reduction.
- Claiming certification from use of an industry framework alone.
Your next action
Request the scope and input sheet behind one media-emissions estimate before using it to rank a plan.
Sources & scope
Frameworks, worksheets and hypothetical examples are original editorial synthesis. Linked primary sources support only the stated concepts. Source checking is not an independent audit of effectiveness. No named human author or reviewer is claimed.
- Ad Net Zero: Global Media Sustainability Framework, Digital Implementation Guide v1.3 →Primary industry methodology · Supports: Describes modeled digital-media emissions components and scope boundaries, and warns that lower estimates need not equal real-world reductions. The comparison worksheet does not certify any provider or environmental claim.