Skip to content
https://nsc.org

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
0
REVIEW
2
PASS
4
INFO
0
Device:
Mobile Desktop
Checks
6
4 PASS 2 REVIEW
B
Carbon Budget
33th percentile
REVIEW
33th percentile
Info::
0.44g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 67% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 33th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.44g

33rd percentile

Cleaner than 67% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 27% cleaner ✓
vs Target 13% cleaner ✓
B
Transfer Efficiency
85% efficient
REVIEW
85% efficient
Info::
Transfer efficiency: 85%
An estimated 283 KB (15%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 283 KB of unused JavaScript. This wasted data produces 0.07g of unnecessary CO2 per page view.
85% efficient

Total waste: 283 KB (15% of page weight)

Unused JS 283 KB

0.07g unnecessary CO2 per visit

Actual transfer 1891 KB
Theoretical minimum 1607 KB
Potential savings 283 KB (0.07g CO2)

See Deep Analysis sections above for specific optimizations.

A
CO2 Per Page Load
0.44g CO2 per view
PASS
0.44g CO2 per view
Info::
0.44g CO2 per page view
This page transfers 1.8 MB, producing an estimated 0.44g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.09g, end-user device 0.34g.
Got: 0.44g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 52.5 kg CO2/year
With 10,000 page views per month, this page would generate approximately 52.5 kg of CO2 annually — equivalent to charging 6556 smartphones.
Info::
Green hosting reduces data center emissions

0.44g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 67% of websites

Sustainable Web Design model v4 · Page size: 1.8 MB

Your site
0.44g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.01g
Network
0.09g
End-user device
0.34g
At 10,000 monthly views: Monthly: 4.4 kg · Annual: 52.5 kg · ≈ 6556 smartphone charges
A+
Green Hosting
Green (both)
PASS
Green (both)
Info::
Both hosting and CDN use renewable energy
Got: Hosting: Cloudflare, CDN: Cloudflare
Info::
Cloudflare: Verified by the Green Web Foundation
Info::
Cloudflare: 100% renewable energy for global network since 2019
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 Cloudflare✓CDN Cloudflare✓

Cloudflare: Verified by the Green Web Foundation

Cloudflare: 100% renewable energy for global network since 2019

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 15 KB (vs 1891 KB first visit). 55 of 56 resources are served from browser cache, saving 0.43g CO2 per repeat visit.
Info::
Repeat visit: 0.00g CO2 (first visit: 0.44g)
First visit
1891 KB
Repeat visit
15 KB

99% reduction on repeat visits

Saving 0.43g CO2 per returning visitor

55 resources served from cache · 1 resources re-downloaded

A+
Green Hosting
Whether the site is served from green-energy infrastructure
PASS

Green Hosting

This site is hosted on green energy infrastructure

Provider: Cloudflare

All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.

Send Feedback