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https://seattle.gov

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
78
GRADE
C
FIX
1
REVIEW
2
PASS
3
INFO
0
Device:
Mobile Desktop
Checks
6
3 PASS 2 REVIEW 1 FIX
D
Green Hosting
Action
Not green
FIX
Not green
Info::
No confirmed renewable energy commitment detected
Consider providers like Cloudflare, Google Cloud, or Vercel that match 100% of their energy use with renewables.
Info::
AWS: Renewable energy varies by region; committed to 100% by 2025
Info::
AWS CloudFront: Renewable varies by edge location
Info::
Green hosting status based on known provider commitments
Green hosting detection uses a curated database of provider renewable energy commitments. This is not a real-time verification. For authoritative checks, visit thegreenwebfoundation.org.
Green HostingNot Green Hosted
Hosting AWS✗CDN AWS CloudFront✗

AWS: Renewable energy varies by region; committed to 100% by 2025

AWS CloudFront: Renewable varies by edge location

Based on known provider commitments. Verify at thegreenwebfoundation.org

B
Transfer Efficiency
75% efficient
REVIEW
75% efficient
Info::
Transfer efficiency: 75%
An estimated 311 KB (25%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 311 KB of unused JavaScript. This wasted data produces 0.09g of unnecessary CO2 per page view.
75% efficient

Total waste: 311 KB (25% of page weight)

Unused JS 311 KB

0.09g unnecessary CO2 per visit

Actual transfer 1250 KB
Theoretical minimum 939 KB
Potential savings 311 KB (0.09g CO2)

See Deep Analysis sections above for specific optimizations.

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A
CO2 Per Page Load
0.35g CO2 per view
PASS
0.35g CO2 per view
Info::
0.35g CO2 per page view
This page transfers 1.2 MB, producing an estimated 0.35g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.06g, network 0.06g, end-user device 0.22g.
Got: 0.35g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 41.5 kg CO2/year
With 10,000 page views per month, this page would generate approximately 41.5 kg of CO2 annually — equivalent to charging 5188 smartphones.

0.35g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 76% of websites

Sustainable Web Design model v4 · Page size: 1.2 MB

Your site
0.35g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.06g
Network
0.06g
End-user device
0.22g
At 10,000 monthly views: Monthly: 3.5 kg · Annual: 41.5 kg · ≈ 5188 smartphone charges
A+
Repeat Visit Weight
99% cached
PASS
99% cached
Info::
99% reduction on repeat visits
Returning visitors download only 10 KB (vs 1250 KB first visit). 38 of 39 resources are served from browser cache, saving 0.34g CO2 per repeat visit.
Info::
Repeat visit: 0.00g CO2 (first visit: 0.35g)
First visit
1250 KB
Repeat visit
10 KB

99% reduction on repeat visits

Saving 0.34g CO2 per returning visitor

38 resources served from cache · 1 resources re-downloaded

A
Carbon Budget
24th percentile
PASS
24th percentile
Info::
0.35g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 76% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 24th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.35g

24th percentile

Cleaner than 76% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 42% cleaner ✓
vs Target 31% cleaner ✓
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

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