This translation has not been editorially reviewed yet. The German version is authoritative. Deutsche Fassung

CO₂ & EmpCo

At what amount of data does the measured value contradict the statement “green website”?

If you advertise “green websites”, “sustainable web design” or “climate-friendly web pages”, the check holds this claim against the measured value of the same run. If the page with the claim loads more than 3,000 KB per view, the measured value contradicts the text. The finding costs 5 points in the EmpCo part; whether it misleads in the individual case is checked by a person.

How the check recognises the claim

It searches the visible text of the measured page for the phrases “grüne Website” and “grüne Webseite”, “green website”, “nachhaltige Website”, “nachhaltiges Webdesign” and “klimafreundliche Website”, each also in the plural. As with all environmental claims, the check skips questions, quotations in quotation marks and code and example blocks. The same sentence can also count as a generic environmental claim, with its own deduction of 5 points. If it names a concrete characteristic, such as “green electricity”, it stays with this one finding.

The cross-check against the measured value

In the same run, the check measures how many bytes a view of the page transfers: document, scripts, style sheets, images, fonts and videos, also from third-party servers. If the total is above 3,000 KB, the finding is raised. For comparison: the CO₂ part of the same audit area already reports a page as heavy from 2.5 MB (2,560 KB). The 3,000 KB limit was set by euid.com; it is above the median of the websites measured by the HTTP Archive (Web Almanac 2024: 2,311 KB on phones, 2,652 KB on desktop).

What the directive says

Under Art. 6(1) of the Unfair Commercial Practices Directive, a commercial practice is misleading if it contains false information or can deceive consumers about essential characteristics of a product, and thereby causes or is likely to cause them to take a transactional decision. Directive (EU) 2024/825 explicitly added environmental and social characteristics to this list. If you sell web design and show your own site as an example, you are advertising with this characteristic. The check establishes the contradiction between text and measured value; whether it misleads in the individual case is judged by a person.

Examples

Home page of an agency

Not met

Wir gestalten grüne Websites für den Mittelstand.
(Startseite: 4.600 KB je Aufruf)

Passes

Unsere Startseite lädt 780 KB je Aufruf (gemessen am 12. Oktober 2026).
Sie liegt bei einem Hoster, der bei der Green Web Foundation
mit Ökostrom-Nachweis eingetragen ist.

In the report, audit area CO₂ & EmpCo, read the measured data volume of the page that carries the claim.
Reduce the data volume: images at display size as WebP or AVIF, videos only on a click, remove unnecessary scripts and fonts.
Then order a re-measurement. If the page loads at most 3,000 KB per view, this finding is settled.
Then back the claim with the measured value and the date of the measurement. If the page stays above 3,000 KB, change the claim.

Deutsche Fassung dieser Seite

FAQ

Is 3,000 KB a legal limit?

The 3,000 KB limit was set by euid.com; under the law, every claim is judged individually. Up to 3,000 KB the page stays free of this finding. The sentence can still count as a generic environmental claim; a concrete characteristic in the same sentence, such as “green electricity”, settles this second finding.

Does a host with green electricity help against this finding?

For this finding only the data volume counts. A host with green electricity proof at the Green Web Foundation lowers the estimated CO₂ value per view and brings 8 points in the CO₂ part.

Which data volume counts if the claim is on a particular page?

The data volume of the same page: the check holds the text of a page against its own weight. If the claim is on the home page, the weight of the home page counts.

What is a good data volume?

For page weight, the CO₂ part gives the full score up to 2.5 MB. Using this check’s method, a 1 MB page comes to about 0.35 g CO₂ per view, and about 0.25 g with a host that has green electricity proof. The HTTP Archive shows where a page stands compared with other websites.