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Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
76
GRADE
C
FIX
2
REVIEW
2
PASS
2
INFO
0
Device:
Mobile Desktop
Checks
6
2 PASS 2 REVIEW 2 FIX
D
CO2 Per Page Load
Action
1.20g CO2 per view
FIX
1.20g CO2 per view
Warning::
1.20g CO2 per page view
This page transfers 5.1 MB, producing an estimated 1.20g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.03g, network 0.25g, end-user device 0.93g.
Got: 1.20g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 144.5 kg CO2/year
With 10,000 page views per month, this page would generate approximately 144.5 kg of CO2 annually — equivalent to charging 18065 smartphones.
Info::
Green hosting reduces data center emissions

1.20g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 33% of websites

Sustainable Web Design model v4 · Page size: 5.1 MB

Your site
1.20g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.03g
Network
0.25g
End-user device
0.93g
At 10,000 monthly views: Monthly: 12.0 kg · Annual: 144.5 kg · ≈ 18065 smartphone charges
D
Carbon Budget
Action
67th percentile
FIX
67th percentile
Warning::
1.20g CO2 — above the median website (0.60g)
Heavier than an estimated 33% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 67th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

1.20g

67th percentile

Cleaner than 33% of websites

✗ Above the median website

vs Median 101% more
vs Target 141% more
B
Green Hosting
Green (hosting)
REVIEW
Green (hosting)
Info::
Fly.io uses renewable energy
Info::
Fly.io: Carbon offsets for all compute
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 Hosting✓ Green Hosted
Hosting Fly.io✓CDN Not identified✗

Fly.io: Carbon offsets for all compute

Based on known provider commitments. Verify at thegreenwebfoundation.org

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

Green Hosting

No green hosting detected

A+
Repeat Visit Weight
99% cached
PASS
99% cached
Info::
99% reduction on repeat visits
Returning visitors download only 43 KB (vs 5210 KB first visit). 45 of 47 resources are served from browser cache, saving 1.19g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 1.20g)
First visit
5210 KB
Repeat visit
43 KB

99% reduction on repeat visits

Saving 1.19g CO2 per returning visitor

45 resources served from cache · 2 resources re-downloaded

A+
Transfer Efficiency
91% efficient
PASS
91% efficient
Info::
Transfer efficiency: 91%
Only 468 KB of potential savings identified. Your page is well-optimized for size.
91% efficient

Total waste: 468 KB (9% of page weight)

Unused JS 468 KB

0.11g unnecessary CO2 per visit

Actual transfer 5210 KB
Theoretical minimum 4741 KB
Potential savings 468 KB (0.11g CO2)

See Deep Analysis sections above for specific optimizations.

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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