https://rhs.org.uk
Sustainability
· 6 checks — CO2 emissions, green hosting, repeat-visit weight, carbon budget, and transfer efficiency rolled into one auditable list.SCORE
84
GRADE
B
FIX
0
REVIEW
3
PASS
3
INFO
0
Checks
63 PASS 3 REVIEW
BCO2 Per Page Load0.60g CO2 per viewREVIEW
CO2 Per Page Load
0.60g CO2 per view
0.60g CO2 per view
Info::
0.60g CO2 per page view
This page transfers 2.6 MB, producing an estimated 0.60g of CO2 per visit using the Sustainable Web Design model (v4). Breakdown: data center 0.02g, network 0.12g, end-user device 0.46g.
Got: 0.60g CO2 Expected: < 0.50g (sustainability target)
Info::
At 10,000 monthly views: 72.4 kg CO2/year
With 10,000 page views per month, this page would generate approximately 72.4 kg of CO2 annually — equivalent to charging 9055 smartphones.
Info::
Green hosting reduces data center emissions
0.60g
Carbon Footprint per page view
✗ Above sustainability target (0.50g)
Cleaner than 50% of websites
Sustainable Web Design model v4 · Page size: 2.6 MB
Your site
0.60g
Top 10%
0.20g
Target
0.50g
Median website
0.60g
Energy Breakdown
Data center
0.02g
Network
0.12g
End-user device
0.46g
At 10,000 monthly views: Monthly: 6.0 kg · Annual: 72.4 kg · ≈ 9055 smartphone charges
BCarbon Budget50th percentileREVIEW
Carbon Budget
50th percentile
50th percentile
Warning::
0.60g CO2 — above the median website (0.60g)
Heavier than an estimated 50% of websites. Reducing page weight, optimizing images, and removing unused JavaScript would lower the carbon footprint. See the Performance tab.
Info::
Estimated 50th percentile
Compared to: top 10% = 0.20g, target = 0.50g, median = 0.60g per page view.
Top 10%
Target
Median website
0.60g
50th percentile
Cleaner than 50% of websites
✗ Above the median website
vs Median 1% more
vs Target 21% more
BTransfer Efficiency80% efficientREVIEW
Transfer Efficiency
80% efficient
80% efficient
Info::
Transfer efficiency: 80%
An estimated 520 KB (20%) could be eliminated: 0 KB via better compression, 0 KB via modern image formats, 520 KB of unused JavaScript. This wasted data produces 0.12g of unnecessary CO2 per page view.
Total waste: 520 KB (20% of page weight)
Unused JS 520 KB
0.12g unnecessary CO2 per visit
Actual transfer 2611 KB
Theoretical minimum 2090 KB
Potential savings 520 KB (0.12g CO2)
See Deep Analysis sections above for specific optimizations.
A+Green HostingGreen (both)PASS
Green Hosting
Green (both)
Green (both)
Info::
Both hosting and CDN use renewable energy
Got: Hosting: Cloudflare, CDN: Cloudflare
Info::
Cloudflare: Verified by the Green Web Foundation
Info::
Cloudflare: 100% renewable energy for global network since 2019
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 Cloudflare✓CDN Cloudflare✓
Cloudflare: Verified by the Green Web Foundation
Cloudflare: 100% renewable energy for global network since 2019
Based on known provider commitments. Verify at thegreenwebfoundation.org
A+Repeat Visit Weight99% cachedPASS
Repeat Visit Weight
99% cached
99% cached
Info::
99% reduction on repeat visits
Returning visitors download only 21 KB (vs 2611 KB first visit). 101 of 104 resources are served from browser cache, saving 0.60g CO2 per repeat visit.
Info::
Repeat visit: 0.00g CO2 (first visit: 0.60g)
First visit
2611 KB
Repeat visit
21 KB
99% reduction on repeat visits
Saving 0.60g CO2 per returning visitor
101 resources served from cache · 3 resources re-downloaded
A+Green HostingWhether the site is served from green-energy infrastructurePASS
Green Hosting
Whether the site is served from green-energy infrastructure
Green Hosting
This site is hosted on green energy infrastructure
Provider: Cloudflare
All checks on this page are automated. Results are estimates - run targeted manual reviews when the score affects a release decision.