Skip to content
https://www.prefect.io

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
80
GRADE
B
FIX
0
REVIEW
3
PASS
3
INFO
0
Device:
Mobile Desktop
Checks
6
3 PASS 3 REVIEW
B
Carbon Budget
34th percentile
REVIEW
34th percentile
Info::
0.45g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 66% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 34th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.45g

34th percentile

Cleaner than 66% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 25% cleaner ✓
vs Target 10% cleaner ✓
C
Transfer Efficiency
Action
68% efficient
REVIEW
68% efficient
Warning::
Transfer efficiency: 68%
An estimated 631 KB (32%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 631 KB of unused JavaScript. This wasted data produces 0.15g of unnecessary CO2 per page view.
68% efficient

Total waste: 631 KB (32% of page weight)

Unused JS 631 KB

0.15g unnecessary CO2 per visit

Actual transfer 1944 KB
Theoretical minimum 1313 KB
Potential savings 631 KB (0.15g 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
CO2 Per Page Load
0.45g CO2 per view
PASS
0.45g CO2 per view
Info::
0.45g CO2 per page view
This page transfers 1.9 MB, producing an estimated 0.45g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.09g, end-user device 0.35g.
Got: 0.45g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 53.9 kg CO2/year
With 10,000 page views per month, this page would generate approximately 53.9 kg of CO2 annually — equivalent to charging 6742 smartphones.
Info::
Green hosting reduces data center emissions

0.45g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 66% of websites

Sustainable Web Design model v4 · Page size: 1.9 MB

Your site
0.45g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.01g
Network
0.09g
End-user device
0.35g
At 10,000 monthly views: Monthly: 4.5 kg · Annual: 53.9 kg · ≈ 6742 smartphone charges
A
Green Hosting
Green (cdn)
PASS
Green (cdn)
Info::
Vercel CDN uses renewable energy
Since most traffic is served through the CDN, the majority of data transfer energy is renewable.
Info::
Vercel: Hosted on AWS/Google Cloud with renewable energy commitments
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 Next.js✗CDN Vercel✓

Vercel: Hosted on AWS/Google Cloud with renewable energy commitments

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 23 KB (vs 1944 KB first visit). 146 of 148 resources are served from browser cache, saving 0.44g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.45g)
First visit
1944 KB
Repeat visit
23 KB

99% reduction on repeat visits

Saving 0.44g CO2 per returning visitor

146 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.

Send Feedback