https://www.javalf.com
Sustainability
· 8 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
81
GRADE
B
FIX
2
REVIEW
1
PASS
4
INFO
1
Checks
84 PASS 1 REVIEW 2 FIX
DCO2 Per Page LoadAction0.84g CO2 per viewFIX
CO2 Per Page Load
Action0.84g CO2 per view
0.84g CO2 per view
Info::
0.84g CO2 per page view
This page transfers 3.6 MB, producing an estimated 0.84g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.02g, network 0.17g, end-user device 0.65g.
Got: 0.84g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 101.0 kg CO2/year
With 10,000 page views per month, this page would generate approximately 101.0 kg of CO2 annually — equivalent to charging 12622 smartphones.
Info::
Green hosting reduces data center emissions
0.84g
Carbon Footprint per page view
✗ Above sustainability target (0.50g)
Cleaner than 44% of websites
Sustainable Web Design model v4 · Page size: 3.6 MB
Your site
0.84g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.02g
Network
0.17g
End-user device
0.65g
At 10,000 monthly views: Monthly: 8.4 kg · Annual: 101.0 kg · ≈ 12622 smartphone charges
DCarbon BudgetAction56th percentileFIX
Carbon Budget
Action56th percentile
56th percentile
Warning::
0.84g CO2 — above the median website (0.60g)
Heavier than an estimated 44% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 56th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
0.84g
56th percentile
Cleaner than 44% of websites
✗ Above the median website
vs Median 40% more
vs Target 68% more
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+Green HostingGreen (both)PASS
Green Hosting
Green (both)
Green (both)
Info::
Both hosting and CDN use renewable energy
Got: Hosting: Google Cloud, CDN: Fastly
Info::
Google Cloud: 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 Google Cloud✓CDN Fastly✓
Google Cloud: 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 Weight93% cachedPASS
Repeat Visit Weight
93% cached
93% cached
Info::
93% reduction on repeat visits
Returning visitors download only 268 KB (vs 3640 KB first visit). 282 of 284 resources are served from browser cache, saving 0.78g CO2 per repeat visit.
Info::
Repeat visit: 0.06g CO2 (first visit: 0.84g)
First visit
3640 KB
Repeat visit
268 KB
93% reduction on repeat visits
Saving 0.78g CO2 per returning visitor
282 resources served from cache · 2 resources re-downloaded
A+Transfer Efficiency90% efficientPASS
Transfer Efficiency
90% efficient
90% efficient
Info::
Transfer efficiency: 90%
Only 350 KB of potential savings identified. Your page is well-optimized for size.
Total waste: 350 KB (10% of page weight)
Unused JS 350 KB
0.08g unnecessary CO2 per visit
Actual transfer 3640 KB
Theoretical minimum 3290 KB
Potential savings 350 KB (0.08g CO2)
See Deep Analysis sections above for specific optimizations.
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: Google Cloud
Image Optimization42 images, 3162 KB total, 204 KB wastedINFO
Image Optimization
42 images, 3162 KB total, 204 KB wasted
Image Optimization Audit
Total Images
42
Total Size
3162 KB
Oversized
3
Wasted
204 KB
38 missing dimensions 28 missing lazy loading
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.