Skip to content
https://bl.uk

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
64
GRADE
D
FIX
2
REVIEW
3
PASS
1
INFO
0
Device:
Mobile Desktop
Checks
6
1 PASS 3 REVIEW 2 FIX
D
Green Hosting
Action
Not green
FIX
Not green
Info::
No confirmed renewable energy commitment detected
Consider providers like Cloudflare, Google Cloud, or Vercel that match 100% of their energy use with renewables.
Info::
Azure: Microsoft is carbon-negative; Azure renewable varies by region
Info::
Azure CDN: Inherits Azure regional renewable mix
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 HostingNot Green Hosted
Hosting Azure✗CDN Azure CDN✗

Azure: Microsoft is carbon-negative; Azure renewable varies by region

Azure CDN: Inherits Azure regional renewable mix

Based on known provider commitments. Verify at thegreenwebfoundation.org

D
Carbon Budget
Action
52th percentile
FIX
52th percentile
Warning::
0.68g CO2 — above the median website (0.60g)
Heavier than an estimated 48% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 52th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.68g

52nd percentile

Cleaner than 48% of websites

✗ Above the median website

vs Median 13% more
vs Target 35% more
B
CO2 Per Page Load
0.68g CO2 per view
REVIEW
0.68g CO2 per view
Info::
0.68g CO2 per page view
This page transfers 2.4 MB, producing an estimated 0.68g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.13g, network 0.12g, end-user device 0.43g.
Got: 0.68g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 81.3 kg CO2/year
With 10,000 page views per month, this page would generate approximately 81.3 kg of CO2 annually — equivalent to charging 10159 smartphones.

0.68g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 48% of websites

Sustainable Web Design model v4 · Page size: 2.4 MB

Your site
0.68g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.13g
Network
0.12g
End-user device
0.43g
At 10,000 monthly views: Monthly: 6.8 kg · Annual: 81.3 kg · ≈ 10159 smartphone charges
C
Transfer Efficiency
Action
70% efficient
REVIEW
70% efficient
Warning::
Transfer efficiency: 70%
An estimated 733 KB (30%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 733 KB of unused JavaScript. This wasted data produces 0.20g of unnecessary CO2 per page view.
70% efficient

Total waste: 733 KB (30% of page weight)

Unused JS 733 KB

0.20g unnecessary CO2 per visit

Actual transfer 2449 KB
Theoretical minimum 1715 KB
Potential savings 733 KB (0.20g 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+
Repeat Visit Weight
98% cached
PASS
98% cached
Info::
98% reduction on repeat visits
Returning visitors download only 52 KB (vs 2449 KB first visit). 47 of 48 resources are served from browser cache, saving 0.66g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.68g)
First visit
2449 KB
Repeat visit
52 KB

98% reduction on repeat visits

Saving 0.66g CO2 per returning visitor

47 resources served from cache · 1 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