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Sustainability

· 7 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
80
GRADE
B
FIX
1
REVIEW
3
PASS
3
INFO
0
Device:
Mobile Desktop
Checks
7
3 PASS 3 REVIEW 1 FIX
D
Green Hosting
Action
Unknown
FIX
Unknown
Info::
Hosting provider could not be identified
Without knowing the provider, we cannot determine their energy sourcing. Check with your hosting provider about their renewable energy commitments.
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 HostingUnable to Determine
Hosting Not identified✗CDN Not identified✗

Based on known provider commitments. Verify at thegreenwebfoundation.org

C
Transfer Efficiency
Action
71% efficient
REVIEW
71% efficient
Warning::
Transfer efficiency: 71%
An estimated 218 KB (29%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 218 KB of unused JavaScript. This wasted data produces 0.06g of unnecessary CO2 per page view.
71% efficient

Total waste: 218 KB (29% of page weight)

Unused JS 218 KB

0.06g unnecessary CO2 per visit

Actual transfer 755 KB
Theoretical minimum 537 KB
Potential savings 218 KB (0.06g CO2)

See Deep Analysis sections above for specific optimizations.

B
Web Font Weight Variants
No detectable Google Fonts weights
REVIEW
No detectable Google Fonts weights
Info::
No detectable Google Fonts weights
The analyzer detects font weights via Google Fonts URL parameters (~70% of font-using sites). Self-hosted fonts and non-Google CDN fonts aren't visible to URL-based detection. If you self-host fonts, manually audit how many @font-face weights you ship -- 2-3 weights per family is typically enough; 5+ is usually unused payload.
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
0.21g CO2 per view
PASS
0.21g CO2 per view
Info::
0.21g CO2 per page view
This page transfers 0.7 MB, producing an estimated 0.21g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.04g, network 0.04g, end-user device 0.13g.
Got: 0.21g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 25.1 kg CO2/year
With 10,000 page views per month, this page would generate approximately 25.1 kg of CO2 annually — equivalent to charging 3133 smartphones.

0.21g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 90% of websites

Sustainable Web Design model v4 · Page size: 0.7 MB

Your site
0.21g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.04g
Network
0.04g
End-user device
0.13g
At 10,000 monthly views: Monthly: 2.1 kg · Annual: 25.1 kg · ≈ 3133 smartphone charges
A+
Repeat Visit Weight
94% cached
PASS
94% cached
Info::
94% reduction on repeat visits
Returning visitors download only 42 KB (vs 755 KB first visit). 51 of 52 resources are served from browser cache, saving 0.20g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.21g)
First visit
755 KB
Repeat visit
42 KB

94% reduction on repeat visits

Saving 0.20g CO2 per returning visitor

51 resources served from cache · 1 resources re-downloaded

A+
Carbon Budget
10th percentile
PASS
10th percentile
Info::
0.21g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 90% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 10th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.21g

10th percentile

Cleaner than 90% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 65% cleaner ✓
vs Target 58% 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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