european-union.europa.eu/index_en

The numbers

First visit

0.171 g CO₂e

Return visit

<0.001 g CO₂e

Hosting

unknown

LCP

144 ms

CLS

0.022

TTFB

14 ms

At 10,000 views a month this page emits about 15.4 kg CO₂e a year, roughly 63 km in an average petrol car. The estimate assumes 75% new and 25% returning visitors, a measured cache reload ratio of 0%, and world-average grid intensity. How we calculate this

1. Convert and compress imagessave ~0.014 g/visit (122 kB)Medium impact · quick fix

   7 images (271 kB) ship in legacy formats (JPEG/PNG/GIF).

   Serve AVIF (or WebP) with responsive srcset sizes, and re-compress oversized files. AVIF typically halves JPEG weight at the same visual quality.

   • institutions-and-bodies_2.jpg74 kB
   • EU-countries_2_0.jpg70 kB
   • AI-Gigafactories.jpg41 kB
   • History-of-the-EU_2.jpg39 kB
   • AI-transparency-obligations%202.jpg27 kB

   WSG 2.9: Optimize media to reduce resource use
2. Reduce JavaScript payloadsave ~0.013 g/visit (121 kB)Medium impact · moderate effort

   27 scripts total 483 kB on the wire (1.70 MB decoded). Bundles this size usually carry a lot of unused code.

   Split bundles per route, tree-shake dependencies, and audit with a bundle analyzer or coverage profile. A 25% cut is a conservative target for bundles this size.

   • js_z8oUnLU2E9HM0CMrcsGP6jG8A5Now14HbdoG-l_cU8…94 kB
   • js_z8oUnLU2E9HM0CMrcsGP6jG8A5Now14HbdoG-l_cU8…94 kB
   • load.js44 kB
   • load.js44 kB
   • webtools.etrans.js30 kB

   WSG 3.2: Minify and remove unused codeWSG 3.3: Modularize bandwidth-heavy components
3. Verify your hosting energyMedium impact · moderate effort

   This host has not published renewable energy evidence with the Green Web Foundation, so its energy source is unknown.

   Choose a provider listed in the Green Web Directory, or ask your current provider to publish evidence (and a carbon.txt). This cuts the data-center share of every single page view.

   • carbon.txtNo carbon.txt found at the site root; publishing one is the lightest first step.

   WSG 4.1: Use sustainable hosting
4. Upgrade compression beyond gzipsave ~0.011 g/visit (96 kB)Advisory · quick fix

   638 kB of text ships gzip-compressed; Brotli or Zstandard would cut roughly another 15-20%, and browsers without them fall back to gzip automatically.

   Serve precompressed Brotli for static text assets (highest level, compressed at build time) and enable Brotli or zstd for dynamic responses; keep gzip only as the fallback.

   • js_z8oUnLU2E9HM0CMrcsGP6jG8A5Now14HbdoG-l_cU8…94 kB
   • js_z8oUnLU2E9HM0CMrcsGP6jG8A5Now14HbdoG-l_cU8…94 kB
   • css_K3VXKueEMVw366P5ae96pX4jho_IOHcPkSx6oZeP0…53 kB
   • css_K3VXKueEMVw366P5ae96pX4jho_IOHcPkSx6oZeP0…53 kB
   • load.js44 kB

   WSG 4.3: Reduce data transfer with compression
5. Stop downloading the same asset twicesave ~0.0065 g/visit (58 kB)Advisory · quick fix

   7 assets were fetched more than once in a single page load (93 kB of repeated transfer).

   Usually a script injected twice or cache-busting query strings that differ per reference. Load each asset once and let the HTTP cache do its job.

   • duet.esm.js2 downloads · 2.6 kB
   • logo-eu--en.svg2 downloads · 12 kB
   • jquery.min.js2 downloads · 56 kB
   • wr_survey.js2 downloads · 1.5 kB
   • load.js2 downloads · 89 kB

   WSG 3.2: Minify and remove unused code
6. Remove the entry redirectAdvisory · quick fix

   The address that was scanned goes through 1 redirect before the document is served, ending at https://european-union.europa.eu/index_en. Every hop is a full round trip on a connection that has not warmed up yet.

   Point links, sitemaps and canonical tags at the final address, and make the host redirect in one hop rather than chaining http to https to www.

   • https://europa.eu/redirects to https://european-union.europa.eu/index_en

   WSG 4.4: Setup necessary error pages and redirection links
7. Upgrade connections to HTTP/2 or HTTP/3Advisory · quick fix

   1 host serves five or more resources over HTTP/1.1, paying per-request connection and header overhead newer protocols eliminate.

   Enable HTTP/2 (or HTTP/3) on the server or move the assets behind a CDN that speaks it; multiplexing makes many small requests nearly free.

   • ec.europa.eu6 requests over http/1.1

   WSG 3.1: Set goals based on performance and energy impact

Where the bytes are

• JavaScript483 kB · 27 req
• Images405 kB · 12 req
• CSS243 kB · 21 req
• HTML23 kB · 2 req
• Data (XHR)937 B · 2 req
• Other0 B · 3 req