https://stib-mivb.brussels
Sustainability
· 8 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
56
GRADE
D
FIX
4
REVIEW
2
PASS
1
INFO
1
Checks
81 PASS 2 REVIEW 4 FIX
DCO2 Per Page LoadAction1.35g CO2 per viewFIX
CO2 Per Page Load
Action1.35g CO2 per view
1.35g CO2 per view
Warning::
1.35g CO2 per page view
This page transfers 4.8 MB, producing an estimated 1.35g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.25g, network 0.23g, end-user device 0.86g.
Got: 1.35g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 161.7 kg CO2/year
With 10,000 page views per month, this page would generate approximately 161.7 kg of CO2 annually — equivalent to charging 20209 smartphones.
1.35g
Carbon Footprint per page view
✗ Above sustainability target (0.50g)
Cleaner than 29% of websites
Sustainable Web Design model v4 · Page size: 4.8 MB
Your site
1.35g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.25g
Network
0.23g
End-user device
0.86g
At 10,000 monthly views: Monthly: 13.5 kg · Annual: 161.7 kg · ≈ 20209 smartphone charges
DGreen HostingActionUnknownFIX
Green Hosting
ActionUnknown
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
FCarbon BudgetAction71th percentileFIX
Carbon Budget
Action71th percentile
71th percentile
Warning::
1.35g CO2 — above the median website (0.60g)
Heavier than an estimated 29% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 71th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
1.35g
71st percentile
Cleaner than 29% of websites
✗ Above the median website
vs Median 125% more
vs Target 169% more
FTransfer EfficiencyAction38% efficientFIX
Transfer Efficiency
Action38% efficient
38% efficient
Critical::
Transfer efficiency: 38%
An estimated 3008 KB (62%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 3008 KB of unused JavaScript. This wasted data produces 0.83g of unnecessary CO2 per page view.
Total waste: 3008 KB (62% of page weight)
Unused JS 3008 KB
0.83g unnecessary CO2 per visit
Actual transfer 4871 KB
Theoretical minimum 1863 KB
Potential savings 3008 KB (0.83g CO2)
See Deep Analysis sections above for specific optimizations.
BWeb Font Weight VariantsNo detectable Google Fonts weightsREVIEW
Web Font Weight Variants
No detectable Google Fonts weights
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.
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+Repeat Visit Weight100% cachedPASS
Repeat Visit Weight
100% cached
100% cached
Info::
100% reduction on repeat visits
Returning visitors download only 10 KB (vs 4871 KB first visit). 81 of 83 resources are served from browser cache, saving 1.34g CO2 per repeat visit.
Info::
Repeat visit: 0.00g CO2 (first visit: 1.35g)
First visit
4871 KB
Repeat visit
10 KB
100% reduction on repeat visits
Saving 1.34g CO2 per returning visitor
81 resources served from cache · 2 resources re-downloaded
Image Optimization14 images, 149 KB total, 72 KB wastedINFO
Image Optimization
14 images, 149 KB total, 72 KB wasted
Image Optimization Audit
Total Images
14
Total Size
149 KB
Oversized
2
Wasted
72 KB
12 missing alt text 14 missing dimensions 12 missing lazy loading
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.