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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
80
GRADE
B
FIX
1
REVIEW
3
PASS
3
INFO
1
Device:
Mobile Desktop
Checks
8
3 PASS 3 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::
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 gunicorn✗CDN Not identified✗

Based on known provider commitments. Verify at thegreenwebfoundation.org

B
Transfer Efficiency
85% efficient
REVIEW
85% efficient
Info::
Transfer efficiency: 85%
An estimated 117 KB (15%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 117 KB of unused JavaScript. This wasted data produces 0.03g of unnecessary CO2 per page view.
85% efficient

Total waste: 117 KB (15% of page weight)

Unused JS 117 KB

0.03g unnecessary CO2 per visit

Actual transfer 795 KB
Theoretical minimum 677 KB
Potential savings 117 KB (0.03g 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
0.22g CO2 per view
PASS
0.22g CO2 per view
Info::
0.22g CO2 per page view
This page transfers 0.8 MB, producing an estimated 0.22g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.04g, network 0.04g, end-user device 0.14g.
Got: 0.22g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 26.4 kg CO2/year
With 10,000 page views per month, this page would generate approximately 26.4 kg of CO2 annually — equivalent to charging 3298 smartphones.

0.22g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 89% of websites

Sustainable Web Design model v4 · Page size: 0.8 MB

Your site
0.22g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.04g
Network
0.04g
End-user device
0.14g
At 10,000 monthly views: Monthly: 2.2 kg · Annual: 26.4 kg · ≈ 3298 smartphone charges
A+
Repeat Visit Weight
96% cached
PASS
96% cached
Info::
96% reduction on repeat visits
Returning visitors download only 31 KB (vs 795 KB first visit). 17 of 18 resources are served from browser cache, saving 0.21g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.22g)
First visit
795 KB
Repeat visit
31 KB

96% reduction on repeat visits

Saving 0.21g CO2 per returning visitor

17 resources served from cache · 1 resources re-downloaded

A
Carbon Budget
11th percentile
PASS
11th percentile
Info::
0.22g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 89% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 11th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.22g

11th percentile

Cleaner than 89% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 63% cleaner ✓
vs Target 56% cleaner ✓
Image Optimization
7 images, 62 KB total, 51 KB wasted
INFO

Image Optimization Audit

Total Images

7

Total Size

62 KB

Oversized

1

Wasted

51 KB

7 missing dimensions 4 missing lazy loading
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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