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Sustainability

· 8 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
70
GRADE
C
FIX
2
REVIEW
2
PASS
3
INFO
1
Device:
Mobile Desktop
Checks
8
3 PASS 2 REVIEW 2 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::
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 Not identified✗CDN Varnish✗

Based on known provider commitments. Verify at thegreenwebfoundation.org

F
Transfer Efficiency
Action
31% efficient
FIX
31% efficient
Critical::
Transfer efficiency: 31%
An estimated 693 KB (69%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 693 KB of unused JavaScript. This wasted data produces 0.19g of unnecessary CO2 per page view.
31% efficient

Total waste: 693 KB (69% of page weight)

Unused JS 693 KB

0.19g unnecessary CO2 per visit

Actual transfer 1007 KB
Theoretical minimum 314 KB
Potential savings 693 KB (0.19g 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
0.28g CO2 per view
PASS
0.28g CO2 per view
Info::
0.28g CO2 per page view
This page transfers 1.0 MB, producing an estimated 0.28g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.05g, network 0.05g, end-user device 0.18g.
Got: 0.28g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 33.4 kg CO2/year
With 10,000 page views per month, this page would generate approximately 33.4 kg of CO2 annually — equivalent to charging 4178 smartphones.

0.28g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 83% of websites

Sustainable Web Design model v4 · Page size: 1.0 MB

Your site
0.28g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.05g
Network
0.05g
End-user device
0.18g
At 10,000 monthly views: Monthly: 2.8 kg · Annual: 33.4 kg · ≈ 4178 smartphone charges
A+
Repeat Visit Weight
81% cached
PASS
81% cached
Info::
81% reduction on repeat visits
Returning visitors download only 193 KB (vs 1007 KB first visit). 17 of 20 resources are served from browser cache, saving 0.22g CO2 per repeat visit.
Info::
Repeat visit: 0.05g CO2 (first visit: 0.28g)
First visit
1007 KB
Repeat visit
193 KB

81% reduction on repeat visits

Saving 0.22g CO2 per returning visitor

17 resources served from cache · 3 resources re-downloaded

A
Carbon Budget
17th percentile
PASS
17th percentile
Info::
0.28g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 83% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 17th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.28g

17th percentile

Cleaner than 83% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 54% cleaner ✓
vs Target 44% cleaner ✓
Image Optimization
1 images, 0 KB total, 0 KB wasted
INFO

Image Optimization Audit

Total Images

1

Total Size

0 KB

Oversized

1

1 missing alt text 1 missing dimensions
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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