https://curbed.com
Sustainability
· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
90
GRADE
A
FIX
0
REVIEW
1
PASS
5
INFO
0
Checks
65 PASS 1 REVIEW
BTransfer Efficiency83% efficientREVIEW
Transfer Efficiency
83% efficient
83% efficient
Info::
Transfer efficiency: 83%
An estimated 291 KB (17%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 291 KB of unused JavaScript. This wasted data produces 0.07g of unnecessary CO2 per page view.
Total waste: 291 KB (17% of page weight)
Unused JS 291 KB
0.07g unnecessary CO2 per visit
Actual transfer 1762 KB
Theoretical minimum 1470 KB
Potential savings 291 KB (0.07g CO2)
See Deep Analysis sections above for specific optimizations.
ACO2 Per Page Load0.41g CO2 per viewPASS
CO2 Per Page Load
0.41g CO2 per view
0.41g CO2 per view
Info::
0.41g CO2 per page view
This page transfers 1.7 MB, producing an estimated 0.41g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.08g, end-user device 0.31g.
Got: 0.41g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 48.9 kg CO2/year
With 10,000 page views per month, this page would generate approximately 48.9 kg of CO2 annually — equivalent to charging 6110 smartphones.
Info::
Green hosting reduces data center emissions
0.41g
Carbon Footprint per page view
✓ Below sustainability target (0.50g)
Cleaner than 70% of websites
Sustainable Web Design model v4 · Page size: 1.7 MB
Your site
0.41g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.01g
Network
0.08g
End-user device
0.31g
At 10,000 monthly views: Monthly: 4.1 kg · Annual: 48.9 kg · ≈ 6110 smartphone charges
A+Green HostingGreen (both)PASS
Green Hosting
Green (both)
Green (both)
Info::
Both hosting and CDN use renewable energy
Got: Hosting: Axis12 Ltd, CDN: Fastly
Info::
Axis12 Ltd: Verified by the Green Web Foundation
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 Axis12 Ltd✓CDN Fastly✓
Axis12 Ltd: Verified by the Green Web Foundation
Fastly: 100% renewable energy for edge network
Based on known provider commitments. Verify at thegreenwebfoundation.org
A+Repeat Visit Weight86% cachedPASS
Repeat Visit Weight
86% cached
86% cached
Info::
86% reduction on repeat visits
Returning visitors download only 241 KB (vs 1762 KB first visit). 112 of 121 resources are served from browser cache, saving 0.35g CO2 per repeat visit.
Info::
Repeat visit: 0.06g CO2 (first visit: 0.41g)
First visit
1762 KB
Repeat visit
241 KB
86% reduction on repeat visits
Saving 0.35g CO2 per returning visitor
112 resources served from cache · 9 resources re-downloaded
ACarbon Budget30th percentilePASS
Carbon Budget
30th percentile
30th percentile
Info::
0.41g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 70% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 30th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
0.41g
30th percentile
Cleaner than 70% of websites
✓ Below the Web Sustainability Guidelines target
vs Median 32% cleaner ✓
vs Target 19% cleaner ✓
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
Whether the site is served from green-energy infrastructure
Green Hosting
This site is hosted on green energy infrastructure
Provider: Axis12 Ltd
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.