# Website Carbon proxy metrics

Current website CO2 calculations (such as co2.js) are *very* broad brush, and won't always change even if you make improvements. However, there are easily collectable metrics that relate well.

> Rarely, can we directly measure our application's carbon cost, but if we follow a resource chain down and it eventually has a link to carbon emissions, then that is a good proxy for carbon.

Cedd Burge

www.linkedin.com/in/cedd-burge-90507027/

github.com/ceddlyburge

[@cuddlyburger](https://twitter.com/cuddlyburger)

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| Principle | Client | Server |
| ---------------------- | --------- | ---------------------------- |
| Carbon (efficiency) | CPU usage | CPU usage |
| Electricity | CPU usage | CPU usage |
| Carbon intensity | - | Power Usage Efficiency (PUE) |
| Embodied carbon | CPU usage | CPU usage |
| Energy Proportionality | - | *Server utilisation?* |

| Measurement | Client | Server |
| ------------------ | ------------------------ | ------------------ |
| Carbon (emissions) | - | Vendor calculators |
| Energy | CPU Usage | CPU usage |
| Cost | - | Cost |
| Networking | Transfer size / distance | |
| Performance | CPU usage | CPU usage |

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| | Total Transfer Size<br />(121 pages) | Total CPU Client (benchmarked) |
| :---------- | :----------------------------------: | :----------------------------: |
| First Load | 7.27 Mb | 203 |
| Second Load | 0.28 Mb | 185 |
| Mobile | 7.43 Mb | 163 |

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| Reccommendations | |
| ------------------------------------------ | ---------------------------- |
| Limit robots | |
| Delete content which isn’t human reachable | This still gets read by bots |
| Sign the [Sustainable Web Manifesto](https://www.sustainablewebmanifesto.com/) | Obviously :) |
| Optimise images | |
| Set cache-control headers | |
| Reduce page size and javascript | |
| Reduce mobile page size | |
| Simplify css | |

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