The verdict in three sentences
For a 900-employee company in scope of the CSRD, eco-designing the corporate website against a recognised framework such as the W3C Web Sustainability Guidelines or the French RGESN is a measurable project: EUR 3,000 to 8,000 for the audit, EUR 20,000 to 50,000 for a full rebuild, over 3 to 5 months. The concrete gain is twofold: pages 2 to 4 times lighter, therefore faster and better scored by Google, and a figure in g CO2e per page view that the sustainability team can include in its report. The website will never weigh much in the overall carbon footprint, but it is visible, verifiable proof that practice matches messaging.
What the frameworks cover and what the audit measures
The RGESN groups 78 criteria in 9 families: strategy, specifications, architecture, UX and interface, content, frontend, backend, hosting and algorithms. The W3C guidelines cover similar ground. Neither is mandatory for a private company, but both provide an auditable grid, which matters when an auditor or CSRD assurance provider asks how your claims were produced.
| Metric | Typical corporate site 2026 | Target after eco-design | Measurement method |
|---|---|---|---|
| Average page weight | 2.5-4 MB | 0.6-1.2 MB | Dev tools, EcoIndex |
| HTTP requests per page | 80-150 | 25-50 | Network analysis |
| EcoIndex score | E to F | B to C | EcoIndex |
| Footprint per page view | 1.2-2 g CO2e | 0.3-0.6 g CO2e | EcoIndex or Website Carbon model |
| Mobile LCP | 3.5-5 s | under 2 s | Lighthouse, CrUX |
| Third-party scripts | 10-25 | 3-6 | Tag inventory |
| Autoplay videos | Common | None | Content review |
These are 2026 estimates observed on industrial group corporate sites. The audit establishes your actual baseline on a sample of 10 to 20 representative pages.
Cost of an eco-designed project: from diagnosis to rebuild
| Service | 2026 range (EUR, excl. VAT) | Timeline | Deliverable |
|---|---|---|---|
| Sustainability audit on 10-20 pages | 3,000-8,000 | 3-5 weeks | Eco-design statement, prioritised action plan |
| Quick wins on the existing site | 6,000-15,000 | 4-8 weeks | AVIF images, system fonts, script removal |
| Eco-designed rebuild (40-80 pages) | 20,000-50,000 | 3-5 months | Static or hybrid site, lean design |
| Renewable-powered hosting | 30-300 per month | 1 week | Host certificate, EU location |
| Website carbon dashboard | 2,000-5,000 | 2-4 weeks | Monthly g CO2e and weight tracking |
| Editor training | 1,200-3,000 | 1-2 days | Lean publishing rules |
The most underestimated item is content governance: an eco-designed site that later receives 20 MB PDFs and uncompressed videos loses half its gains within a year. Training editors and enforcing a file size limit in the CMS are cheap and decisive investments.
What goes into the sustainability report
Under the CSRD, digital mostly falls within scope 3 emissions and the environmental policy described under ESRS E1. The website is a tiny share of emissions, but you can document: the eco-design statement with the share of criteria met, the estimated annual footprint (page views multiplied by g CO2e per page), the renewable energy share of your host and year-on-year progress. A site with 600,000 page views per year moving from 1.6 to 0.45 g CO2e per page avoids roughly 690 kg CO2e per year: modest, but traceable and consistent.
Mini case study
Aoife, head of sustainability at a 900-employee industrial company in Dublin, commissions an audit at EUR 5,500, then a 60-page eco-designed rebuild at EUR 38,000 and green hosting at EUR 120 per month. Average page weight drops from 3.2 MB to 0.9 MB, mobile LCP from 4.1 s to 1.7 s. With 600,000 page views a year, the estimated footprint falls from 960 kg to 270 kg CO2e. Mobile bounce rate drops from 58 % to 44 %, lifting applications received through the careers page by about 20 %. Total first-year cost: EUR 44,940, comparable to a conventional rebuild, with a sustainability metric on top.
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FAQ
Is eco-design mandatory for a private company?
No, in France the RGESN mainly applies to public services, and Ireland has no equivalent obligation. For a private company it is voluntary, but 78 criteria give an objective basis for a sustainability claim.
Is an eco-designed site less attractive?
No, it is more restrained: careful typography, AVIF images, animations kept to the essentials. Many premium sites already ship under 1 MB per page.
Does eco-design help SEO?
Indirectly yes, since an LCP under 2.5 s and a light page improve Core Web Vitals. Teams often see 10 to 25 % more mobile organic traffic once metrics turn green.
Can we eco-design without rebuilding everything?
Yes, targeted work at EUR 6,000 to 15,000 often cuts page weight by 40 to 60 %. A rebuild is justified when the CMS or theme forces dozens of unnecessary scripts.
How do we make the g CO2e per page figure reliable?
Use a public method such as EcoIndex and keep it consistent year after year. Assurance providers mostly expect a constant, documented methodology.
Let's scope your project. We scope your sustainability audit or eco-designed rebuild with a page scope, an indicative budget and metrics you can use in your sustainability report. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
