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https://duke.edu

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
68
GRADE
D
FIX
3
REVIEW
1
PASS
2
INFO
0
Device:
Mobile Desktop
Checks
6
2 PASS 1 REVIEW 3 FIX
F
CO2 Per Page Load
Action
1.54g CO2 per view
FIX
1.54g CO2 per view
Warning::
1.54g CO2 per page view
This page transfers 5.4 MB, producing an estimated 1.54g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.29g, network 0.27g, end-user device 0.99g.
Got: 1.54g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 185.1 kg CO2/year
With 10,000 page views per month, this page would generate approximately 185.1 kg of CO2 annually — equivalent to charging 23132 smartphones.

1.54g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 24% of websites

Sustainable Web Design model v4 · Page size: 5.4 MB

Your site
1.54g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.29g
Network
0.27g
End-user device
0.99g
At 10,000 monthly views: Monthly: 15.4 kg · Annual: 185.1 kg · ≈ 23132 smartphone charges
D
Green Hosting
Action
Not green
FIX
Not green
Info::
No confirmed renewable energy commitment detected
Consider providers like Cloudflare, Google Cloud, or Vercel that match 100% of their energy use with renewables.
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 HostingNot Green Hosted
Hosting Apache HTTP Server✗CDN Not identified✗

Based on known provider commitments. Verify at thegreenwebfoundation.org

F
Carbon Budget
Action
76th percentile
FIX
76th percentile
Warning::
1.54g CO2 — above the median website (0.60g)
Heavier than an estimated 24% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 76th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

1.54g

76th percentile

Cleaner than 24% of websites

✗ Above the median website

vs Median 157% more
vs Target 208% more
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A+
Repeat Visit Weight
99% cached
PASS
99% cached
Info::
99% reduction on repeat visits
Returning visitors download only 36 KB (vs 5576 KB first visit). 55 of 56 resources are served from browser cache, saving 1.53g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 1.54g)
First visit
5576 KB
Repeat visit
36 KB

99% reduction on repeat visits

Saving 1.53g CO2 per returning visitor

55 resources served from cache · 1 resources re-downloaded

A+
Transfer Efficiency
97% efficient
PASS
97% efficient
Info::
Transfer efficiency: 97%
Only 147 KB of potential savings identified. Your page is well-optimized for size.
97% efficient

Total waste: 147 KB (3% of page weight)

Unused JS 147 KB

0.04g unnecessary CO2 per visit

Actual transfer 5576 KB
Theoretical minimum 5428 KB
Potential savings 147 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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