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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
D
CO2 Per Page Load
Action
1.06g CO2 per view
FIX
1.06g CO2 per view
Warning::
1.06g CO2 per page view
This page transfers 3.7 MB, producing an estimated 1.06g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.20g, network 0.18g, end-user device 0.68g.
Got: 1.06g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 127.2 kg CO2/year
With 10,000 page views per month, this page would generate approximately 127.2 kg of CO2 annually — equivalent to charging 15901 smartphones.

1.06g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 37% of websites

Sustainable Web Design model v4 · Page size: 3.7 MB

Your site
1.06g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.20g
Network
0.18g
End-user device
0.68g
At 10,000 monthly views: Monthly: 10.6 kg · Annual: 127.2 kg · ≈ 15901 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

D
Carbon Budget
Action
63th percentile
FIX
63th percentile
Warning::
1.06g CO2 — above the median website (0.60g)
Heavier than an estimated 37% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 63th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

1.06g

63rd percentile

Cleaner than 37% of websites

✗ Above the median website

vs Median 77% more
vs Target 112% 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 3833 KB first visit). 54 of 55 resources are served from browser cache, saving 1.05g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 1.06g)
First visit
3833 KB
Repeat visit
36 KB

99% reduction on repeat visits

Saving 1.05g CO2 per returning visitor

54 resources served from cache · 1 resources re-downloaded

A+
Transfer Efficiency
96% efficient
PASS
96% efficient
Info::
Transfer efficiency: 96%
Only 147 KB of potential savings identified. Your page is well-optimized for size.
96% efficient

Total waste: 147 KB (4% of page weight)

Unused JS 147 KB

0.04g unnecessary CO2 per visit

Actual transfer 3833 KB
Theoretical minimum 3685 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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