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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
87
GRADE
B
FIX
0
REVIEW
2
PASS
4
INFO
0
Device:
Mobile Desktop
Checks
6
4 PASS 2 REVIEW
B
Transfer Efficiency
78% efficient
REVIEW
78% efficient
Info::
Transfer efficiency: 78%
An estimated 237 KB (22%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 237 KB of unused JavaScript. This wasted data produces 0.05g of unnecessary CO2 per page view.
78% efficient

Total waste: 237 KB (22% of page weight)

Unused JS 237 KB

0.05g unnecessary CO2 per visit

Actual transfer 1069 KB
Theoretical minimum 832 KB
Potential savings 237 KB (0.05g 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
0.25g CO2 per view
PASS
0.25g CO2 per view
Info::
0.25g CO2 per page view
This page transfers 1.0 MB, producing an estimated 0.25g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.05g, end-user device 0.19g.
Got: 0.25g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 29.7 kg CO2/year
With 10,000 page views per month, this page would generate approximately 29.7 kg of CO2 annually — equivalent to charging 3708 smartphones.
Info::
Green hosting reduces data center emissions

0.25g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 86% of websites

Sustainable Web Design model v4 · Page size: 1.0 MB

Your site
0.25g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.01g
Network
0.05g
End-user device
0.19g
At 10,000 monthly views: Monthly: 2.5 kg · Annual: 29.7 kg · ≈ 3708 smartphone charges
A
Green Hosting
Green (cdn)
PASS
Green (cdn)
Info::
Fastly CDN uses renewable energy
Since most traffic is served through the CDN, the majority of data transfer energy is renewable.
Info::
Fastly: 100% renewable energy for edge network
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 Not identified✗CDN Fastly✓

Fastly: 100% renewable energy for edge network

Based on known provider commitments. Verify at thegreenwebfoundation.org

A+
Repeat Visit Weight
87% cached
PASS
87% cached
Info::
87% reduction on repeat visits
Returning visitors download only 139 KB (vs 1069 KB first visit). 110 of 112 resources are served from browser cache, saving 0.22g CO2 per repeat visit.
Info::
Repeat visit: 0.03g CO2 (first visit: 0.25g)
First visit
1069 KB
Repeat visit
139 KB

87% reduction on repeat visits

Saving 0.22g CO2 per returning visitor

110 resources served from cache · 2 resources re-downloaded

A
Carbon Budget
14th percentile
PASS
14th percentile
Info::
0.25g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 86% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 14th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.25g

14th percentile

Cleaner than 86% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 59% cleaner ✓
vs Target 51% 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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