Skip to content
https://essex.ac.uk

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
53
GRADE
F
FIX
3
REVIEW
2
PASS
1
INFO
0
Device:
Mobile Desktop
Checks
6
1 PASS 2 REVIEW 3 FIX
F
CO2 Per Page Load
Action
2.74g CO2 per view
FIX
2.74g CO2 per view
Critical::
2.74g CO2 per page view
This page transfers 9.7 MB, producing an estimated 2.74g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.51g, network 0.47g, end-user device 1.76g.
Got: 2.74g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 328.3 kg CO2/year
With 10,000 page views per month, this page would generate approximately 328.3 kg of CO2 annually — equivalent to charging 41037 smartphones.

2.74g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 5% of websites

Sustainable Web Design model v4 · Page size: 9.7 MB

Your site
2.74g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.51g
Network
0.47g
End-user device
1.76g
At 10,000 monthly views: Monthly: 27.4 kg · Annual: 328.3 kg · ≈ 41037 smartphone charges
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::
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 Not identified✗

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

Based on known provider commitments. Verify at thegreenwebfoundation.org

F
Carbon Budget
Action
95th percentile
FIX
95th percentile
Warning::
2.74g CO2 — above the median website (0.60g)
Heavier than an estimated 5% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 95th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

2.74g

95th percentile

Cleaner than 5% of websites

✗ Above the median website

vs Median 356% more
vs Target 447% more
B
Transfer Efficiency
89% efficient
REVIEW
89% efficient
Info::
Transfer efficiency: 89%
An estimated 1133 KB (11%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 1133 KB of unused JavaScript. This wasted data produces 0.31g of unnecessary CO2 per page view.
89% efficient

Total waste: 1133 KB (11% of page weight)

Unused JS 1133 KB

0.31g unnecessary CO2 per visit

Actual transfer 9892 KB
Theoretical minimum 8758 KB
Potential savings 1133 KB (0.31g 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 153 KB (vs 9892 KB first visit). 379 of 388 resources are served from browser cache, saving 2.69g CO2 per repeat visit.
Info::
Repeat visit: 0.04g CO2 (first visit: 2.74g)
First visit
9892 KB
Repeat visit
153 KB

98% reduction on repeat visits

Saving 2.69g CO2 per returning visitor

379 resources served from cache · 9 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