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https://sheffield.ac.uk

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
88
GRADE
B
FIX
0
REVIEW
3
PASS
3
INFO
0
Device:
Mobile Desktop
Checks
6
3 PASS 3 REVIEW
B
CO2 Per Page Load
0.58g CO2 per view
REVIEW
0.58g CO2 per view
Info::
0.58g CO2 per page view
This page transfers 2.5 MB, producing an estimated 0.58g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.12g, end-user device 0.45g.
Got: 0.58g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 69.6 kg CO2/year
With 10,000 page views per month, this page would generate approximately 69.6 kg of CO2 annually — equivalent to charging 8698 smartphones.
Info::
Green hosting reduces data center emissions

0.58g

Carbon Footprint per page view

✗ Above sustainability target (0.50g)

Cleaner than 53% of websites

Sustainable Web Design model v4 · Page size: 2.5 MB

Your site
0.58g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.01g
Network
0.12g
End-user device
0.45g
At 10,000 monthly views: Monthly: 5.8 kg · Annual: 69.6 kg · ≈ 8698 smartphone charges
B
Carbon Budget
47th percentile
REVIEW
47th percentile
Info::
0.58g CO2 — below the median website (0.60g)
Better than an estimated 53% of websites, but above the sustainability target of 0.50g. Reducing page weight would help reach the target.
Info::
Estimated 47th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.58g

47th percentile

Cleaner than 53% of websites

✗ Above the median website

vs Median 3% cleaner ✓
vs Target 16% more
C
Green Hosting
Action
Whether the site is served from green-energy infrastructure
REVIEW

Green Hosting

No green hosting detected

A
Green Hosting
Green (cdn)
PASS
Green (cdn)
Info::
Fastly CDN uses renewable energy
Since most traffic is served through the CDN, the majority of data transfer energy is renewable.
Info::
Fastly: 100% renewable energy for edge network
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 Acquia Cloud Platform✗CDN Fastly✓

Fastly: 100% renewable energy for edge network

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 24 KB (vs 2508 KB first visit). 50 of 51 resources are served from browser cache, saving 0.57g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.58g)
First visit
2508 KB
Repeat visit
24 KB

99% reduction on repeat visits

Saving 0.57g CO2 per returning visitor

50 resources served from cache · 1 resources re-downloaded

A+
Transfer Efficiency
94% efficient
PASS
94% efficient
Info::
Transfer efficiency: 94%
Only 141 KB of potential savings identified. Your page is well-optimized for size.
94% efficient

Total waste: 141 KB (6% of page weight)

Unused JS 141 KB

0.03g unnecessary CO2 per visit

Actual transfer 2508 KB
Theoretical minimum 2367 KB
Potential savings 141 KB (0.03g CO2)

See Deep Analysis sections above for specific optimizations.

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

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