web sustainability guidelines

the W3C Web Sustainability Guidelines (WSG) 1.0 define 93 guidelines across 4 categories for reducing the environmental impact of websites and digital products. this is a reference. and a self-audit.

this page — claimed (build time)

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total weight
0 B
javascript
0g
co2 per visit
8/8
WSG checks

this page — measured (live, this load)

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total transfer
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javascript
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co2 (this load)
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claim vs measured

live readout uses Resource Timing API. cached resources report 0 transferSize and are excluded honestly.

the four pillars

user experience design 28 guidelines
design decisions that reduce unnecessary resource consumption.
  • assess and research visitor needs before designing
  • use the minimum amount of pages and page components
  • select user interface patterns that reduce load on the network
  • provide accessible, usable, inclusive, and universal interfaces
  • create a frictionless, lightweight experience for the user
  • avoid manipulative patterns and dark patterns
  • provide adequate notification and control of system-level settings
  • optimize media assets for sustainability
  • develop a sustainable product or service strategy
web development 36 guidelines
code-level choices that minimize environmental impact.
  • use HTML elements correctly for semantic structure
  • avoid unnecessary or an overabundance of assets
  • choose the lowest-carbon technology for every task
  • use native browser features rather than third-party libraries
  • minimize the number of third-party requests
  • use resource hints and service workers for performance
  • provide for offline and limited-connectivity experiences
  • compress everything that can be compressed
  • use the most efficient image format and loading strategy
  • use efficient CSS selectors and properties
hosting, infrastructure & systems 22 guidelines
server and infrastructure decisions with real carbon cost.
  • choose a green web host powered by renewable energy
  • optimize server utilization with sustainable scaling
  • use the minimum amount of server-side infrastructure
  • use edge computing and CDNs for static content
  • automate carbon monitoring and set reduction targets
  • implement caching headers and content negotiation
  • compress all transferred data at the server level
  • use the most efficient protocols available
business strategy & product management 7 guidelines
organizational commitments that sustain technical improvements.
  • define sustainability goals and assign ownership
  • verify suppliers and partners meet sustainability criteria
  • include sustainability as a key product requirement
  • communicate digital sustainability efforts transparently
  • train teams in sustainable web practices

self-audit

how does this page measure against the WSG development guidelines?

✓  semantic HTML no divs pretending to be sections. real headings, lists, details.
✓  no unnecessary assets zero images. zero web fonts. zero icons.
✓  lowest-carbon technology pure astro. static HTML at build time. no runtime.
✓  native browser features <details> for disclosure. no JS accordion.
✓  zero third-party requests no analytics. no CDN fonts. no tracking.
✓  compression gzip/brotli at the edge. nothing to optimize further.
✓  efficient CSS scoped styles. no framework CSS. no unused selectors.
✓  client JavaScript zero bytes of bundled JS. ~700b inline measurement script paid in transparency.

the specification

W3C Web Sustainability Guidelines (WSG) 1.0
W3C Community Group Report, published 2024.

the WSG provides 93 actionable guidelines organized under 4 pillars: user experience (28), web development (36), hosting and infrastructure (22), and business strategy (7).

the full specification is at w3c.github.io/sustyweb.
the community group: w3.org/community/sustyweb.
a page about sustainability should be the lightest page on the site. if it isn't, the page is the problem it describes. measured from dist/ at build time: no build.
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