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https://dart.dev

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
87
GRADE
B
FIX
2
REVIEW
1
PASS
3
INFO
0
Device:
Mobile Desktop
Checks
6
3 PASS 1 REVIEW 2 FIX
D
CO2 Per Page Load
Action
0.81g CO2 per view
FIX
0.81g CO2 per view
Info::
0.81g CO2 per page view
This page transfers 3.4 MB, producing an estimated 0.81g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.02g, network 0.17g, end-user device 0.62g.
Got: 0.81g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 97.3 kg CO2/year
With 10,000 page views per month, this page would generate approximately 97.3 kg of CO2 annually — equivalent to charging 12156 smartphones.
Info::
Green hosting reduces data center emissions

0.81g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 44% of websites

Sustainable Web Design model v4 · Page size: 3.4 MB

Your site
0.81g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.02g
Network
0.17g
End-user device
0.62g
At 10,000 monthly views: Monthly: 8.1 kg · Annual: 97.3 kg · ≈ 12156 smartphone charges
D
Carbon Budget
Action
56th percentile
FIX
56th percentile
Warning::
0.81g 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

0.81g

56th percentile

Cleaner than 44% of websites

✗ Above the median website

vs Median 35% more
vs Target 62% more
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::
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
100% cached
PASS
100% cached
Info::
100% reduction on repeat visits
Returning visitors download only 16 KB (vs 3506 KB first visit). 69 of 71 resources are served from browser cache, saving 0.81g CO2 per repeat visit.
Info::
Repeat visit: 0.00g CO2 (first visit: 0.81g)
First visit
3506 KB
Repeat visit
16 KB

100% reduction on repeat visits

Saving 0.81g CO2 per returning visitor

69 resources served from cache · 2 resources re-downloaded

A+
Transfer Efficiency
96% efficient
PASS
96% efficient
Info::
Transfer efficiency: 96%
Only 134 KB of potential savings identified. Your page is well-optimized for size.
96% efficient

Total waste: 134 KB (4% of page weight)

Unused JS 134 KB

0.03g unnecessary CO2 per visit

Actual transfer 3506 KB
Theoretical minimum 3371 KB
Potential savings 134 KB (0.03g 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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