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https://brennancenter.org

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
53th percentile
FIX
53th percentile
Warning::
0.74g CO2 — above the median website (0.60g)
Heavier than an estimated 47% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 53th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.74g

53rd percentile

Cleaner than 47% of websites

✗ Above the median website

vs Median 23% more
vs Target 47% more
B
CO2 Per Page Load
0.74g CO2 per view
REVIEW
0.74g CO2 per view
Info::
0.74g CO2 per page view
This page transfers 3.1 MB, producing an estimated 0.74g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.02g, network 0.15g, end-user device 0.57g.
Got: 0.74g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 88.4 kg CO2/year
With 10,000 page views per month, this page would generate approximately 88.4 kg of CO2 annually — equivalent to charging 11054 smartphones.
Info::
Green hosting reduces data center emissions

0.74g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 47% of websites

Sustainable Web Design model v4 · Page size: 3.1 MB

Your site
0.74g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.02g
Network
0.15g
End-user device
0.57g
At 10,000 monthly views: Monthly: 7.4 kg · Annual: 88.4 kg · ≈ 11054 smartphone charges
B
Transfer Efficiency
83% efficient
REVIEW
83% efficient
Info::
Transfer efficiency: 83%
An estimated 532 KB (17%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 532 KB of unused JavaScript. This wasted data produces 0.12g of unnecessary CO2 per page view.
83% efficient

Total waste: 532 KB (17% of page weight)

Unused JS 532 KB

0.12g unnecessary CO2 per visit

Actual transfer 3188 KB
Theoretical minimum 2656 KB
Potential savings 532 KB (0.12g 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::
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 GoDaddy✗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 31 KB (vs 3188 KB first visit). 119 of 121 resources are served from browser cache, saving 0.73g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.74g)
First visit
3188 KB
Repeat visit
31 KB

99% reduction on repeat visits

Saving 0.73g CO2 per returning visitor

119 resources served from cache · 2 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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