https://www.python.org
Sustainability
· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
93
GRADE
A
FIX
0
REVIEW
2
PASS
4
INFO
0
Checks
64 PASS 2 REVIEW
BTransfer Efficiency76% efficientREVIEW
Transfer Efficiency
76% efficient
76% efficient
Info::
Transfer efficiency: 76%
An estimated 118 KB (24%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 118 KB of unused JavaScript. This wasted data produces 0.03g of unnecessary CO2 per page view.
Total waste: 118 KB (24% of page weight)
Unused JS 118 KB
0.03g unnecessary CO2 per visit
Actual transfer 499 KB
Theoretical minimum 381 KB
Potential savings 118 KB (0.03g CO2)
See Deep Analysis sections above for specific optimizations.
CGreen HostingActionWhether the site is served from green-energy infrastructureREVIEW
Green Hosting
ActionWhether the site is served from green-energy infrastructure
Green Hosting
No green hosting detected
A+CO2 Per Page Load0.12g CO2 per viewPASS
CO2 Per Page Load
0.12g CO2 per view
0.12g CO2 per view
Info::
0.12g CO2 per page view
This page transfers 0.5 MB, producing an estimated 0.12g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.00g, network 0.02g, end-user device 0.09g.
Got: 0.12g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 13.9 kg CO2/year
With 10,000 page views per month, this page would generate approximately 13.9 kg of CO2 annually — equivalent to charging 1732 smartphones.
Info::
Green hosting reduces data center emissions
0.12g
Carbon Footprint per page view
✓ Below sustainability target (0.50g)
Cleaner than 90% of websites
Sustainable Web Design model v4 · Page size: 0.5 MB
Your site
0.12g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.00g
Network
0.02g
End-user device
0.09g
At 10,000 monthly views: Monthly: 1.2 kg · Annual: 13.9 kg · ≈ 1732 smartphone charges
AGreen HostingGreen (cdn)PASS
Green Hosting
Green (cdn)
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 Weight98% cachedPASS
Repeat Visit Weight
98% cached
98% cached
Info::
98% reduction on repeat visits
Returning visitors download only 11 KB (vs 499 KB first visit). 34 of 35 resources are served from browser cache, saving 0.11g CO2 per repeat visit.
Info::
Repeat visit: 0.00g CO2 (first visit: 0.12g)
First visit
499 KB
Repeat visit
11 KB
98% reduction on repeat visits
Saving 0.11g CO2 per returning visitor
34 resources served from cache · 1 resources re-downloaded
A+Carbon Budget10th percentilePASS
Carbon Budget
10th percentile
10th percentile
Info::
0.12g 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
0.12g
10th percentile
Cleaner than 90% of websites
✓ Below the Web Sustainability Guidelines target
vs Median 81% cleaner ✓
vs Target 77% cleaner ✓
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.