Methods

CO2.js exposes two functions that developers can use to return CO2 estimates. This guide will show you how to use the different methods to calculate carbon emissions, and give a brief explanation for each.

perByte()

The perByte() function can be used with both the OneByte and Sustainable Web Design models. We recommend using this function, as it will return a CO2 value (in grams) for raw data transfer using a given model. It can be used for calculating emissions from websites, file uploads, streaming etc.

import { co2 } from '@tgwf/co2'

const oneByte = new co2()

const emissions = oneByte.perByte(1000000);

Here we are using the OneByte model, and using the perByte() function to check the carbon emissions for transferring 1 million bytes.

Accepted parameters

The perByte() function accepts the following parameters:

• bytes
  Required
  Number
  : The value of bytes to estimate emissions for.
• green hosting
  Boolean
  : true if the data being measured is served from a green web host.

perVisit

Sustainable Web Design only

The perVisit() function can only be used with the Sustainable Web Design models. This function includes assumptions the model authors have made about website visitors and caching as part its calculation. For that reason, we recommend only using it if you are comfortable with those assumptions. The perVisit() function is best used for calculating website carbon emissions.

import { co2 } from '@tgwf/co2'

const swd = new co2()

const emissions = swd.perVisit(1000000);

Here we are using the Sustainable Web Design model, and using the perVisit() function to check the carbon emissions for transferring 1 million bytes.

Accepted parameters

The perVisit() function accepts the following parameters:

• bytes
  Required
  Number
  : The value of bytes to estimate emissions for.
• green hosting
  Boolean
  : true if the data being measured is served from a green web host.