https://lisse.nl
Sustainability
· 8 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
75
GRADE
C
FIX
2
REVIEW
3
PASS
2
INFO
1
Checks
82 PASS 3 REVIEW 2 FIX
DCO2 Per Page LoadAction1.03g CO2 per viewFIX
CO2 Per Page Load
Action1.03g CO2 per view
1.03g CO2 per view
Warning::
1.03g CO2 per page view
This page transfers 4.4 MB, producing an estimated 1.03g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.03g, network 0.21g, end-user device 0.79g.
Got: 1.03g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 124.2 kg CO2/year
With 10,000 page views per month, this page would generate approximately 124.2 kg of CO2 annually — equivalent to charging 15519 smartphones.
Info::
Green hosting reduces data center emissions
1.03g
Carbon Footprint per page view
✗ Above sustainability target (0.50g)
Cleaner than 38% of websites
Sustainable Web Design model v4 · Page size: 4.4 MB
Your site
1.03g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.03g
Network
0.21g
End-user device
0.79g
At 10,000 monthly views: Monthly: 10.3 kg · Annual: 124.2 kg · ≈ 15519 smartphone charges
DCarbon BudgetAction62th percentileFIX
Carbon Budget
Action62th percentile
62th percentile
Warning::
1.03g CO2 — above the median website (0.60g)
Heavier than an estimated 38% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 62th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
1.03g
62nd percentile
Cleaner than 38% of websites
✗ Above the median website
vs Median 72% more
vs Target 107% more
BGreen HostingGreen (hosting)REVIEW
Green Hosting
Green (hosting)
Green (hosting)
Info::
Previder BV uses renewable energy
Info::
Previder BV: Verified by the Green Web Foundation
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 Previder BV✓CDN Not identified✗
Previder BV: Verified by the Green Web Foundation
Based on known provider commitments. Verify at thegreenwebfoundation.org
BTransfer Efficiency90% efficientREVIEW
Transfer Efficiency
90% efficient
90% efficient
Info::
Transfer efficiency: 90%
An estimated 449 KB (10%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 449 KB of unused JavaScript. This wasted data produces 0.10g of unnecessary CO2 per page view.
Total waste: 449 KB (10% of page weight)
Unused JS 449 KB
0.10g unnecessary CO2 per visit
Actual transfer 4476 KB
Theoretical minimum 4026 KB
Potential savings 449 KB (0.10g 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.
A+Repeat Visit Weight99% cachedPASS
Repeat Visit Weight
99% cached
99% cached
Info::
99% reduction on repeat visits
Returning visitors download only 25 KB (vs 4476 KB first visit). 74 of 75 resources are served from browser cache, saving 1.03g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 1.03g)
First visit
4476 KB
Repeat visit
25 KB
99% reduction on repeat visits
Saving 1.03g CO2 per returning visitor
74 resources served from cache · 1 resources re-downloaded
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: Previder BV
Image Optimization15 images, 2262 KB total, 1481 KB wastedINFO
Image Optimization
15 images, 2262 KB total, 1481 KB wasted
Image Optimization Audit
Total Images
15
Total Size
2262 KB
Oversized
7
Wasted
1481 KB
9 missing lazy loading
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.