Skip to content
https://bufferapp.com

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
86
GRADE
B
FIX
0
REVIEW
1
PASS
5
INFO
0
Device:
Mobile Desktop
Checks
6
5 PASS 1 REVIEW
C
Transfer Efficiency
Action
75% efficient
REVIEW
75% efficient
Warning::
Transfer efficiency: 75%
An estimated 258 KB (25%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 258 KB of unused JavaScript. This wasted data produces 0.06g of unnecessary CO2 per page view.
75% efficient

Total waste: 258 KB (25% of page weight)

Unused JS 258 KB

0.06g unnecessary CO2 per visit

Actual transfer 1021 KB
Theoretical minimum 763 KB
Potential savings 258 KB (0.06g CO2)

See Deep Analysis sections above for specific optimizations.

A
CO2 Per Page Load
0.24g CO2 per view
PASS
0.24g CO2 per view
Info::
0.24g CO2 per page view
This page transfers 1.0 MB, producing an estimated 0.24g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.05g, end-user device 0.18g.
Got: 0.24g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 28.3 kg CO2/year
With 10,000 page views per month, this page would generate approximately 28.3 kg of CO2 annually — equivalent to charging 3543 smartphones.
Info::
Green hosting reduces data center emissions

0.24g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 87% of websites

Sustainable Web Design model v4 · Page size: 1.0 MB

Your site
0.24g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.01g
Network
0.05g
End-user device
0.18g
At 10,000 monthly views: Monthly: 2.4 kg · Annual: 28.3 kg · ≈ 3543 smartphone charges
A+
Green Hosting
Green (both)
PASS
Green (both)
Info::
Both hosting and CDN use renewable energy
Got: Hosting: Next.js, CDN: Cloudflare
Info::
Next.js: 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 Next.js✓CDN Cloudflare✓

Next.js: 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
93% cached
PASS
93% cached
Info::
93% reduction on repeat visits
Returning visitors download only 70 KB (vs 1021 KB first visit). 48 of 49 resources are served from browser cache, saving 0.22g CO2 per repeat visit.
Info::
Repeat visit: 0.02g CO2 (first visit: 0.24g)
First visit
1021 KB
Repeat visit
70 KB

93% reduction on repeat visits

Saving 0.22g CO2 per returning visitor

48 resources served from cache · 1 resources re-downloaded

A
Carbon Budget
13th percentile
PASS
13th percentile
Info::
0.24g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 87% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 13th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.24g

13th percentile

Cleaner than 87% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 61% cleaner ✓
vs Target 53% cleaner ✓
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