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https://vu.nl

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
58
GRADE
D
FIX
3
REVIEW
2
PASS
1
INFO
0
Device:
Mobile Desktop
Checks
6
1 PASS 2 REVIEW 3 FIX
D
CO2 Per Page Load
Action
1.42g CO2 per view
FIX
1.42g CO2 per view
Warning::
1.42g CO2 per page view
This page transfers 5.0 MB, producing an estimated 1.42g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.26g, network 0.25g, end-user device 0.91g.
Got: 1.42g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 170.4 kg CO2/year
With 10,000 page views per month, this page would generate approximately 170.4 kg of CO2 annually — equivalent to charging 21304 smartphones.

1.42g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 27% of websites

Sustainable Web Design model v4 · Page size: 5.0 MB

Your site
1.42g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.26g
Network
0.25g
End-user device
0.91g
At 10,000 monthly views: Monthly: 14.2 kg · Annual: 170.4 kg · ≈ 21304 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

F
Carbon Budget
Action
73th percentile
FIX
73th percentile
Warning::
1.42g CO2 — above the median website (0.60g)
Heavier than an estimated 27% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 73th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

1.42g

73rd percentile

Cleaner than 27% of websites

✗ Above the median website

vs Median 137% more
vs Target 184% more
C
Transfer Efficiency
Action
67% efficient
REVIEW
67% efficient
Warning::
Transfer efficiency: 67%
An estimated 1703 KB (33%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 1703 KB of unused JavaScript. This wasted data produces 0.47g of unnecessary CO2 per page view.
67% efficient

Total waste: 1703 KB (33% of page weight)

Unused JS 1703 KB

0.47g unnecessary CO2 per visit

Actual transfer 5135 KB
Theoretical minimum 3432 KB
Potential savings 1703 KB (0.47g CO2)

See Deep Analysis sections above for specific optimizations.

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Repeat Visit Weight
97% cached
PASS
97% cached
Info::
97% reduction on repeat visits
Returning visitors download only 155 KB (vs 5135 KB first visit). 36 of 37 resources are served from browser cache, saving 1.38g CO2 per repeat visit.
Info::
Repeat visit: 0.04g CO2 (first visit: 1.42g)
First visit
5135 KB
Repeat visit
155 KB

97% reduction on repeat visits

Saving 1.38g CO2 per returning visitor

36 resources served from cache · 1 resources re-downloaded

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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