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https://thisoldhouse.com

Sustainability

· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.
SCORE
90
GRADE
A
FIX
1
REVIEW
2
PASS
3
INFO
0
Device:
Mobile Desktop
Checks
6
3 PASS 2 REVIEW 1 FIX
D
Green Hosting
Action
Unknown
FIX
Unknown
Info::
Hosting provider could not be identified
Without knowing the provider, we cannot determine their energy sourcing. Check with your hosting provider about their renewable energy commitments.
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 HostingUnable to Determine
Hosting Not identified✗CDN Not identified✗

Based on known provider commitments. Verify at thegreenwebfoundation.org

B
Transfer Efficiency
90% efficient
REVIEW
90% efficient
Info::
Transfer efficiency: 90%
An estimated 64 KB (10%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 64 KB of unused JavaScript. This wasted data produces 0.02g of unnecessary CO2 per page view.
90% efficient

Total waste: 64 KB (10% of page weight)

Unused JS 64 KB

0.02g unnecessary CO2 per visit

Actual transfer 645 KB
Theoretical minimum 580 KB
Potential savings 64 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 0.6 MB, producing an estimated 0.18g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.03g, network 0.03g, end-user device 0.11g.
Got: 0.18g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 21.4 kg CO2/year
With 10,000 page views per month, this page would generate approximately 21.4 kg of CO2 annually — equivalent to charging 2677 smartphones.

0.18g

Carbon Footprint per page view

✓ Below sustainability target (0.50g)

Cleaner than 90% of websites

Sustainable Web Design model v4 · Page size: 0.6 MB

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

Energy Breakdown

Data center
0.03g
Network
0.03g
End-user device
0.11g
At 10,000 monthly views: Monthly: 1.8 kg · Annual: 21.4 kg · ≈ 2677 smartphone charges
A+
Repeat Visit Weight
88% cached
PASS
88% cached
Info::
88% reduction on repeat visits
Returning visitors download only 75 KB (vs 645 KB first visit). 86 of 87 resources are served from browser cache, saving 0.16g CO2 per repeat visit.
Info::
Repeat visit: 0.02g CO2 (first visit: 0.18g)
First visit
645 KB
Repeat visit
75 KB

88% reduction on repeat visits

Saving 0.16g CO2 per returning visitor

86 resources served from cache · 1 resources re-downloaded

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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