CSRD Scope 3 & Website Emissions: What Businesses Must Report in 2026
The Corporate Sustainability Reporting Directive (CSRD) has quietly transformed website carbon emissions from a voluntary green credential into a mandatory disclosure item for tens of thousands of European companies. If your business is in scope — and from 2026, the majority of large companies are — your website's carbon footprint is no longer just a badge. It's an audit-ready number you need to defend.
This guide covers what CSRD requires for digital Scope 3 emissions, which companies are affected in 2026, how to measure and document your website's footprint, and what auditors actually check.
What is Scope 3 Category 11 — and why websites are in it
GHG Protocol Scope 3 Category 11 covers emissions from the "use of sold products" — the energy consumed when customers use a product or service after purchase. For software companies, SaaS platforms, e-commerce businesses, and any organisation with significant online service delivery, the energy used to serve web content to users falls here.
For companies where digital is not the primary product, website emissions typically fall under Scope 3 Category 3 (fuel and energy-related activities) or as part of the broader digital infrastructure footprint. Either way, under ESRS E1 (Climate), companies must disclose all material Scope 3 categories — and "material" is assessed against revenue, strategy, and stakeholder expectations, not just size.
The materiality test: when must you report digital emissions?
CSRD uses a double materiality approach: emissions are material if they are financially significant or if they are significant from an impact perspective. For a retail company with 10 million monthly web visits, even at a conservative 0.5g CO2 per page view, that's 60 tonnes CO2e per year — likely material by both tests. For a 20-person accounting firm with 5,000 monthly visits, the footprint (under 1 tonne) is probably immaterial and needs only a brief explanation in the sustainability report.
CSRD scope timeline: which companies report when
| Phase | Company profile | First report | Covers |
|---|---|---|---|
| Phase 1 | Large public-interest entities, 500+ employees (listed companies, banks, insurers) | 2025 (FY2024 data) | Scope 1, 2, material Scope 3 |
| Phase 2 | Large companies: 2 of 3 criteria — 250+ employees, €40M+ turnover, €20M+ balance sheet | 2026 (FY2025 data) | Scope 1, 2, material Scope 3 |
| Phase 3 | Listed SMEs, small credit institutions, captive insurers | 2027 (FY2026 data) | Simplified VSME standard |
| Non-EU | Non-EU companies with €150M+ EU turnover | 2028 (FY2028 data) | Sector-level reporting |
If your company is in Phase 2 — reporting in 2026 — you need FY2025 data. That means your 2025 website emissions should already be measured and documented. If they aren't, the measurement process starts now: tools like Carbon Badge provide timestamped records per URL that serve as audit evidence.
How to measure website Scope 3 emissions for CSRD
Step 1: Choose a methodology
The Sustainable Web Design Model v4 (published by the Green Web Foundation, 2024) is the widely-accepted standard for website carbon accounting. It calculates CO2 per data byte transferred, adjusting for hosting energy source and global grid carbon intensity. For CSRD purposes, SWD Model v4 provides the methodological consistency auditors expect.
Other methodologies exist (GreenFrame.io's energy profiling, OneClick LCA), but SWD Model v4's transparency and widespread tool support make it the practical choice for CSRD compliance.
Step 2: Measure CO2 per page view for key pages
Use Carbon Badge to measure your homepage and your top 5–10 traffic pages. Record for each: URL tested, CO2 per page view (g), hosting energy status (green/grey), measurement date.
| Page type | Why it matters | Typical CO2/page view range |
|---|---|---|
| Homepage | Usually highest traffic, often heaviest page | 0.3g – 3g |
| Product/service pages | High traffic + transaction value | 0.5g – 5g (image-heavy) |
| Blog/content pages | Often high page count but lighter weight | 0.2g – 1g |
| Checkout/form pages | Critical user flows, often JS-heavy | 0.5g – 2g |
Step 3: Calculate annual emissions
Pull annual page views from your analytics (GA4 or equivalent). For each page type measured:
- Annual CO2 (kg) = (CO2 per page view in grams × annual page views) / 1000
- Sum across all measured page types
- For unmeasured pages, apply the weighted average CO2/page view from your measured sample
Example: 2 million annual page views × 0.8g average CO2/page view = 1,600 kg = 1.6 tonnes CO2e per year. Document this calculation with the input data, formula, and assumptions.
Step 4: Adjust for green hosting
If your hosting is verified renewable (check at the Green Web Foundation directory or via Carbon Badge's hosting check), apply the 0.5 multiplier to the data centre component per SWD Model v4. This is not a rounding — it reflects the significantly lower carbon intensity of renewable data centre electricity. Document your host's renewable energy status with a timestamped Green Web Foundation check.
What CSRD auditors check for digital emissions
Based on early CSRD audit practice from Phase 1 companies (FY2024), auditors focus on five areas when reviewing digital Scope 3 disclosures:
- Methodology documentation — which standard was used, why, and whether it was applied consistently year over year
- Data sources — where did the CO2/page view figures come from, and are they dated?
- Traffic data — are page view figures from an auditable analytics source (GA4 export, server logs)?
- Materiality rationale — is the materiality assessment documented and defensible?
- Year-on-year comparability — can the company demonstrate that measurement methodology is consistent across periods?
The most common audit finding in digital emissions disclosures is inconsistency between the narrative ("we're committed to reducing our digital footprint") and the data (no measurements, no baseline, no targets). Having any documented measurement — even imperfect — is vastly better than having none.
Practical CSRD compliance checklist for website emissions
| Action | Tool / resource | CSRD section |
|---|---|---|
| Measure CO2/page view for top 10 pages | Carbon Badge (free) | ESRS E1-6 (Scope 3) |
| Verify hosting renewable energy status | Green Web Foundation + Carbon Badge | ESRS E1-6 |
| Calculate annual CO2e from traffic × emissions | GA4 export + SWD Model v4 formula | ESRS E1-6 |
| Document methodology with version reference | SWD Model v4 citation (2024) | ESRS 1 (methodology) |
| Perform materiality assessment | Double materiality matrix | ESRS 1 (materiality) |
| Archive measurements with dates | Carbon Badge + spreadsheet | Audit evidence |
| Set reduction target (recommended) | Internal — link to optimisation plan | ESRS E1-4 (targets) |
Beyond compliance: using CSRD as a driver for website optimisation
The companies that benefit most from CSRD digital reporting are those that use the compliance process as an audit of their web performance. A page generating 3g CO2/page view is almost always also a slow, expensive, conversion-killing page. The same optimisations that reduce CO2 — image compression, green hosting, JavaScript reduction, CDN caching — reduce load time and improve Core Web Vitals.
For a full optimisation roadmap, see our 2026 website carbon reduction guide and our 8-step carbon checklist. For benchmarking your scores against industry peers, the 2026 benchmarks by industry are a useful reference point.
Free instant measurement using the Sustainable Web Design Model v4. Get timestamped data you can use as CSRD audit evidence.
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Frequently Asked Questions
Does CSRD require reporting website carbon emissions as Scope 3?
Yes. Website carbon emissions are reportable under CSRD/ESRS E1 as Scope 3 emissions — primarily Category 11 for technology companies and digital service providers. From 2026, Phase 2 companies (250+ employees or €40M+ turnover) must disclose all material Scope 3 categories, and digital operations are increasingly considered material for companies with significant web traffic.
How do you measure website carbon emissions for CSRD reporting?
Use the Sustainable Web Design Model v4 as the standard methodology. Measure CO2/page view for your top traffic pages using Carbon Badge, multiply by annual page views from your analytics, and produce an annual tonne CO2e estimate. Document the methodology, measurement dates, URLs tested, and the traffic data source for auditors.
Which companies must report Scope 3 digital emissions under CSRD in 2026?
Phase 2 companies — those meeting 2 of 3 criteria: 250+ employees, €40M+ turnover, or €20M+ balance sheet — must first report for FY2025 in 2026. Phase 1 companies (500+ employees, public-interest entities) began reporting for FY2024 in 2025. Non-EU companies with €150M+ EU turnover follow from 2028.
What evidence do CSRD auditors expect for website Scope 3 emissions?
Auditors expect a defined methodology (SWD Model v4), timestamped measurements for key pages, annualised emission estimates based on real traffic data, a materiality assessment, and year-over-year comparability. Carbon Badge provides timestamped measurements; combine with GA4 exports for the annual calculation.
Can website carbon badges be used as CSRD evidence?
Yes. Carbon Badge measurements use the SWD Model v4 standard and provide timestamped CO2/page view records per URL. For CSRD purposes, archive your Carbon Badge measurements alongside GA4 traffic data to produce and document your annual tonne CO2e estimate. This combination satisfies audit evidence requirements.
Related: How to measure your website sustainability score 2026 · Website carbon benchmarks by industry 2026 · Scope 3 supply chain emissions guide