Carbon calculations

Every day about 4.6 billion people use the Internet. According to a 2018 study, the use of the Internet in 2025 will consume 20% (!) of all generated electricity and the IT industry will then be responsible for 5.5 % of global CO2 emissions.1

It’s high time to reduce this energy consumption as quickly as possible and to limit the damage to our climate as much as we can. That’s why Zifera tries to visualise the energy consumption of the data traffic from and to your website and we’ll help you 

  • reduce the emissions of carbon gases from the use of your website; 

  • and make a structural contribution to a sustainable future. 

This way, we can reduce the negative impact of your website on the climate.

How do we calculate the impact of your website on the climate? 

The calculations

Step 1

Zifera calculates the CO2 emissions of your website by dividing the total energy consumption of the IT sector by the total data usage of the IT sector. This produces the energy consumption per data unit: the amount of kWh per gigabyte (GB).

The total energy consumption: The figures used in the calculation are based upon research by Andrae and Edler. This study includes a wide spectrum of the energy consumption in the IT industry, such as the network infrastructure and the energy consumption of data centres.2

The total data usage: The total annual data usage of the web is measured in the Nature article: How to stop data centres from gobbling up the world’s electricity.3

The total energy consumption of the IT sector, divided by the total data usage of the IT sector is 1.8 kWh per gigabyte. 

We take into account an average number of times you don’t have to reload information, since files have been pre-downloaded and have been stored in your browser].

Step 2: converting kWh/GB to CO2 emissions

Now that we know the energy consumption per gigabyte, we can calculate the emissions of greenhouse gases. To do so, we use the data from the International Energy Agency (IEA).4

Grey power: 442 grams CO2-equivalents per kWh

Green power: 50 grams CO2-equivalents per kWh

The power consumption of data centres accounts universally for 10 % of the total energy consumption of your website. We consult the database of the Green WebFoundation to see if your website has green hosting. Now we can calculate the energy composition which the traffic from and to your website uses.56

Energy = Bytes of website * 0.81 kWh/GB

CO2 consumption green server = ((Energy * 0.10 %) * 50 grams) + ((energy * 0.90 %) * 442 grams)

CO2 consumption grey server = Energy * 442 grams.

Step 3: measuring the impact of website visits 

Once a month, Zifera scans the composition of all the pages of your website. Zifera keeps track of the number of visitors to your website per page and which device the visitor uses to visit the website. This data is used to calculate the amount of energy the data exchange costs and hence the CO2 emissions it produces.

To give you an idea: viewing a web page costs on average 0.5 grams of CO2

every time. For a website with a monthly average of 10,000 page visits, the energy consumption delivers an annual CO2 emission of 60 kg CO2.

Calculating the climate impact of your website and the privacy of your visitors

The mechanism of the tracking script is simple and meets the European privacy regulations (GDPR). When a visitor gains access to your website after you’ve installed the script, only the URL of the page is forwarded to Zifera. This is completely anonymised and does not contain personal information. This means you won’t need a cookie banner.

Zifera values transparency and greatly appreciates your feedback.

Special thanks to the friendly people of


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