SUSTAINABILITY.md

Template for teams that want a practical, measurable sustainability policy for engineering, accessibility, and AI usage.

Status and ownership

• Status: Draft

  Active

  Archived

• Policy owner: [team or role]
• Last updated: [YYYY-MM-DD]
• Review cadence: [monthly/quarterly]

Team commitment

We commit to reducing digital waste and emissions by making sustainability part of normal delivery work. We optimize for measurable improvement over perfection, and we treat sustainability as a quality attribute alongside reliability, security, performance, and accessibility.

Scope

This policy applies to:

• Repositories: [list]
• Products/services: [list]
• Build and deployment workflows: [list]
• Third-party services and scripts: [list]

Out of scope for now:

• [list known exclusions]

Baseline metrics

Metric	Baseline	Target	Owner	Check cadence
Core page weight	[value]	[value]	[owner]	[cadence]
Request count	[value]	[value]	[owner]	[cadence]
CI compute minutes	[value]	[value]	[owner]	[cadence]
Third-party scripts	[value]	[value]	[owner]	[cadence]
Accessibility violations (critical)	[value]	[value]	[owner]	[cadence]
AI calls per PR	[value]	[value]	[owner]	[cadence]

Pull request requirements

All pull requests should include:

• Expected sustainability impact (increase/decrease/no change)
• Accessibility impact summary
• Third-party impact summary
• AI assistance disclosure when used

PR template fields:

• Sustainability impact:
• Accessibility checks run:
• AI tools used (if any):

Accessibility as code (required checks)

Minimum required CI checks for each pull request:

• Linting for accessibility rules in markup/components
• Automated accessibility testing for changed pages/components
• Keyboard and focus-state checks for interactive elements
• Color contrast checks for text and controls
• Regression gating on critical accessibility failures

Suggested workflow policy:

• Block merge when new critical accessibility violations are introduced.
• Allow temporary exceptions only with issue link, owner, and expiry date.

Sustainability as code (required checks)

Minimum required CI checks for each pull request:

• Page-weight budget checks
• Request-count budget checks
• Third-party script inventory and diff checks
• Media optimization checks
• Build footprint checks (for example CI minutes or job count)

Suggested workflow policy:

• Block merge when budgets regress beyond agreed thresholds.
• Require explicit approval for threshold changes.

AI usage policy

Default behavior

• Prefer deterministic tools first.
• Use AI only when it materially reduces rework or delivery risk.
• Keep prompts small and task-scoped.

Allowed uses

• Refactoring analysis
• Drafting and summarization where deterministic automation is unavailable
• Migration planning and triage

Restricted uses

• No always-on AI generation in CI for routine tasks
• No large-context prompts for trivial formatting or deterministic transforms
• No AI calls when local tooling can produce equivalent output

AI controls

• Limit model size and retries where practical
• Cache reusable outputs
• Track approximate AI call volume per issue/PR
• Review monthly and set reduction goals

Time and space shifting

Time shift

• Run deferrable jobs during lower-carbon windows where practical.
• Define maximum delay bounds for each job type.

Space shift

• Prefer lower-carbon regions/providers when architecture allows.
• Use self-hosted runners for region-aware workloads when needed.

Governance and exceptions

• Labels: sustainability, accessibility, performance-budget, ai-usage, third-party-impact
• Decision owners: [team]
• Exception process:
  1. Open issue with rationale
  2. Define owner and expiry date
  3. Add mitigation plan
  4. Revalidate before expiry

References

• Web Sustainability Guidelines: https://www.w3.org/TR/web-sustainability-guidelines/
• Sustainable Web Design: https://sustainablewebdesign.org/
• Green Web Foundation CO2.js: https://github.com/thegreenwebfoundation/co2.js
• Carbon.txt standard: https://www.thegreenwebfoundation.org/tools/carbon-txt/

Disclosure practices

Consider creating a carbon.txt file in your project root to provide machine-readable sustainability data and disclosure information. This follows the carbon.txt standard developed by the Green Web Foundation, making it easier for tools and services to discover and use your sustainability information.

AI agent instruction block

Use in AGENTS.md, .cursorrules, or system prompts:

Check SUSTAINABILITY.md before proposing or writing changes. Prefer low-compute deterministic solutions. Run required accessibility and sustainability checks in CI. If AI is used, keep context minimal, avoid duplicate calls, and disclose usage in the PR.