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https://uwaterloo.ca

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
83
GRADE
B
FIX
0
REVIEW
2
PASS
4
INFO
0
Device:
Mobile Desktop
Checks
6
4 PASS 2 REVIEW
C
Transfer Efficiency
Action
72% efficient
REVIEW
72% efficient
Warning::
Transfer efficiency: 72%
An estimated 487 KB (28%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 487 KB of unused JavaScript. This wasted data produces 0.11g of unnecessary CO2 per page view.
72% efficient

Total waste: 487 KB (28% of page weight)

Unused JS 487 KB

0.11g unnecessary CO2 per visit

Actual transfer 1760 KB
Theoretical minimum 1273 KB
Potential savings 487 KB (0.11g 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
0.41g CO2 per view
PASS
0.41g CO2 per view
Info::
0.41g CO2 per page view
This page transfers 1.7 MB, producing an estimated 0.41g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.01g, network 0.08g, end-user device 0.31g.
Got: 0.41g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 48.8 kg CO2/year
With 10,000 page views per month, this page would generate approximately 48.8 kg of CO2 annually — equivalent to charging 6104 smartphones.
Info::
Green hosting reduces data center emissions

0.41g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 70% of websites

Sustainable Web Design model v4 · Page size: 1.7 MB

Your site
0.41g
Top 10%
0.20g
Target
0.50g
Median website
0.60g

Energy Breakdown

Data center
0.01g
Network
0.08g
End-user device
0.31g
At 10,000 monthly views: Monthly: 4.1 kg · Annual: 48.8 kg · ≈ 6104 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 Amazon Web Services✗CDN Fastly✓

Fastly: 100% renewable energy for edge network

Based on known provider commitments. Verify at thegreenwebfoundation.org

A+
Repeat Visit Weight
98% cached
PASS
98% cached
Info::
98% reduction on repeat visits
Returning visitors download only 42 KB (vs 1760 KB first visit). 78 of 79 resources are served from browser cache, saving 0.40g CO2 per repeat visit.
Info::
Repeat visit: 0.01g CO2 (first visit: 0.41g)
First visit
1760 KB
Repeat visit
42 KB

98% reduction on repeat visits

Saving 0.40g CO2 per returning visitor

78 resources served from cache · 1 resources re-downloaded

A
Carbon Budget
30th percentile
PASS
30th percentile
Info::
0.41g CO2 — below the sustainability target of 0.50g
Cleaner than an estimated 70% of websites analyzed. This page meets the Web Sustainability Guidelines target.
Info::
Estimated 30th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website

0.41g

30th percentile

Cleaner than 70% of websites

✓ Below the Web Sustainability Guidelines target

vs Median 32% cleaner ✓
vs Target 19% 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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