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https://surrey.ac.uk

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
89
GRADE
B
FIX
0
REVIEW
3
PASS
3
INFO
0
Device:
Mobile Desktop
Checks
6
3 PASS 3 REVIEW
B
Repeat Visit Weight
79% cached
REVIEW
79% cached
Info::
79% reduction on repeat visits
Returning visitors download only 166 KB (vs 779 KB first visit). 44 of 45 resources are served from browser cache, saving 0.14g CO2 per repeat visit.
Info::
Repeat visit: 0.04g CO2 (first visit: 0.18g)
First visit
779 KB
Repeat visit
166 KB

79% reduction on repeat visits

Saving 0.14g CO2 per returning visitor

44 resources served from cache · 1 resources re-downloaded

B
Transfer Efficiency
86% efficient
REVIEW
86% efficient
Info::
Transfer efficiency: 86%
An estimated 105 KB (14%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 105 KB of unused JavaScript. This wasted data produces 0.02g of unnecessary CO2 per page view.
86% efficient

Total waste: 105 KB (14% of page weight)

Unused JS 105 KB

0.02g unnecessary CO2 per visit

Actual transfer 779 KB
Theoretical minimum 674 KB
Potential savings 105 KB (0.02g 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
0.18g CO2 per view
PASS
0.18g CO2 per view
Info::
0.18g CO2 per page view
This page transfers 0.8 MB, producing an estimated 0.18g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.00g, network 0.04g, end-user device 0.14g.
Got: 0.18g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 21.6 kg CO2/year
With 10,000 page views per month, this page would generate approximately 21.6 kg of CO2 annually — equivalent to charging 2702 smartphones.
Info::
Green hosting reduces data center emissions

0.18g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 90% of websites

Sustainable Web Design model v4 · Page size: 0.8 MB

Your site
0.18g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.00g
Network
0.04g
End-user device
0.14g
At 10,000 monthly views: Monthly: 1.8 kg · Annual: 21.6 kg · ≈ 2702 smartphone charges
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 Platform.sh✗CDN Fastly✓

Fastly: 100% renewable energy for edge network

Based on known provider commitments. Verify at thegreenwebfoundation.org

A+
Carbon Budget
10th percentile
PASS
10th percentile
Info::
0.18g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 90% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 10th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.18g

10th percentile

Cleaner than 90% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 70% cleaner ✓
vs Target 64% cleaner ✓
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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