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Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
81
GRADE
B
FIX
1
REVIEW
3
PASS
2
INFO
0
Device:
Mobile Desktop
Checks
6
2 PASS 3 REVIEW 1 FIX
D
Carbon Budget
Action
52th percentile
FIX
52th percentile
Warning::
0.68g CO2 — above the median website (0.60g)
Heavier than an estimated 48% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 52th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.68g

52nd percentile

Cleaner than 48% of websites

✗ Above the median website

vs Median 13% more
vs Target 36% more
B
CO2 Per Page Load
0.68g CO2 per view
REVIEW
0.68g CO2 per view
Info::
0.68g CO2 per page view
This page transfers 2.9 MB, producing an estimated 0.68g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.02g, network 0.14g, end-user device 0.52g.
Got: 0.68g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 81.6 kg CO2/year
With 10,000 page views per month, this page would generate approximately 81.6 kg of CO2 annually — equivalent to charging 10204 smartphones.
Info::
Green hosting reduces data center emissions

0.68g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 48% of websites

Sustainable Web Design model v4 · Page size: 2.9 MB

Your site
0.68g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.02g
Network
0.14g
End-user device
0.52g
At 10,000 monthly views: Monthly: 6.8 kg · Annual: 81.6 kg · ≈ 10204 smartphone charges
B
Transfer Efficiency
86% efficient
REVIEW
86% efficient
Info::
Transfer efficiency: 86%
An estimated 407 KB (14%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 407 KB of unused JavaScript. This wasted data produces 0.09g of unnecessary CO2 per page view.
86% efficient

Total waste: 407 KB (14% of page weight)

Unused JS 407 KB

0.09g unnecessary CO2 per visit

Actual transfer 2943 KB
Theoretical minimum 2535 KB
Potential savings 407 KB (0.09g CO2)

See Deep Analysis sections above for specific optimizations.

C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

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::
Heroku: Runs on AWS; renewable status depends on region
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 Heroku✗CDN Fastly✓

Heroku: Runs on AWS; renewable status depends on region

Fastly: 100% renewable energy for edge network

Based on known provider commitments. Verify at thegreenwebfoundation.org

A+
Repeat Visit Weight
96% cached
PASS
96% cached
Info::
96% reduction on repeat visits
Returning visitors download only 103 KB (vs 2943 KB first visit). 75 of 78 resources are served from browser cache, saving 0.66g CO2 per repeat visit.
Info::
Repeat visit: 0.02g CO2 (first visit: 0.68g)
First visit
2943 KB
Repeat visit
103 KB

96% reduction on repeat visits

Saving 0.66g CO2 per returning visitor

75 resources served from cache · 3 resources re-downloaded

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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