Skip to content
https://cwi.nl

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
70
GRADE
C
FIX
3
REVIEW
1
PASS
2
INFO
0
Device:
Mobile Desktop
Checks
6
2 PASS 1 REVIEW 3 FIX
D
CO2 Per Page Load
Action
1.11g CO2 per view
FIX
1.11g CO2 per view
Warning::
1.11g CO2 per page view
This page transfers 3.9 MB, producing an estimated 1.11g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.21g, network 0.19g, end-user device 0.71g.
Got: 1.11g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 133.4 kg CO2/year
With 10,000 page views per month, this page would generate approximately 133.4 kg of CO2 annually — equivalent to charging 16675 smartphones.

1.11g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 36% of websites

Sustainable Web Design model v4 · Page size: 3.9 MB

Your site
1.11g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.21g
Network
0.19g
End-user device
0.71g
At 10,000 monthly views: Monthly: 11.1 kg · Annual: 133.4 kg · ≈ 16675 smartphone charges
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

D
Carbon Budget
Action
64th percentile
FIX
64th percentile
Warning::
1.11g CO2 — above the median website (0.60g)
Heavier than an estimated 36% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 64th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

1.11g

64th percentile

Cleaner than 36% of websites

✗ Above the median website

vs Median 85% more
vs Target 122% more
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Repeat Visit Weight
100% cached
PASS
100% cached
Info::
100% reduction on repeat visits
Returning visitors download only 19 KB (vs 4019 KB first visit). 26 of 27 resources are served from browser cache, saving 1.11g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 1.11g)
First visit
4019 KB
Repeat visit
19 KB

100% reduction on repeat visits

Saving 1.11g CO2 per returning visitor

26 resources served from cache · 1 resources re-downloaded

A+
Transfer Efficiency
97% efficient
PASS
97% efficient
Info::
Transfer efficiency: 97%
Only 112 KB of potential savings identified. Your page is well-optimized for size.
97% efficient

Total waste: 112 KB (3% of page weight)

Unused JS 112 KB

0.03g unnecessary CO2 per visit

Actual transfer 4019 KB
Theoretical minimum 3907 KB
Potential savings 112 KB (0.03g CO2)

See Deep Analysis sections above for specific optimizations.

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

Send Feedback