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https://kyoto-u.ac.jp

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
88
GRADE
B
FIX
0
REVIEW
2
PASS
4
INFO
0
Device:
Mobile Desktop
Checks
6
4 PASS 2 REVIEW
B
Carbon Budget
32th percentile
REVIEW
32th percentile
Info::
0.43g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 68% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 32th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.43g

32nd percentile

Cleaner than 68% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 29% cleaner ✓
vs Target 15% cleaner ✓
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A
CO2 Per Page Load
0.43g CO2 per view
PASS
0.43g CO2 per view
Info::
0.43g CO2 per page view
This page transfers 1.8 MB, producing an estimated 0.43g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.09g, end-user device 0.33g.
Got: 0.43g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 51.1 kg CO2/year
With 10,000 page views per month, this page would generate approximately 51.1 kg of CO2 annually — equivalent to charging 6383 smartphones.
Info::
Green hosting reduces data center emissions

0.43g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 68% of websites

Sustainable Web Design model v4 · Page size: 1.8 MB

Your site
0.43g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.01g
Network
0.09g
End-user device
0.33g
At 10,000 monthly views: Monthly: 4.3 kg · Annual: 51.1 kg · ≈ 6383 smartphone charges
A
Green Hosting
Green (cdn)
PASS
Green (cdn)
Info::
Fastly CDN uses renewable energy
Since most traffic is served through the CDN, the majority of data transfer energy is renewable.
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 Not identified✗CDN Fastly✓

Fastly: 100% renewable energy for edge network

Based on known provider commitments. Verify at thegreenwebfoundation.org

A+
Repeat Visit Weight
99% cached
PASS
99% cached
Info::
99% reduction on repeat visits
Returning visitors download only 23 KB (vs 1841 KB first visit). 95 of 96 resources are served from browser cache, saving 0.42g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.43g)
First visit
1841 KB
Repeat visit
23 KB

99% reduction on repeat visits

Saving 0.42g CO2 per returning visitor

95 resources served from cache · 1 resources re-downloaded

A+
Transfer Efficiency
92% efficient
PASS
92% efficient
Info::
Transfer efficiency: 92%
Only 151 KB of potential savings identified. Your page is well-optimized for size.
92% efficient

Total waste: 151 KB (8% of page weight)

Unused JS 151 KB

0.04g unnecessary CO2 per visit

Actual transfer 1841 KB
Theoretical minimum 1689 KB
Potential savings 151 KB (0.04g 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.

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