Emissions factors for Microsoft 365 usage
An online service such as Microsoft 365 is very different from an application that runs on a local server or on your computer. Large-scale cloud data storage requires the construction of data centres, which must be cooled and secured. Few studies have examined the specific case of data storage through a cloud-based online service. In 2017, Stanford published the findings of a study on this topic. More recently, in 2021, the German Federal Environment Agency, the equivalent of Ademe in France, published a very detailed analysis of the environmental impact of the life cycle of cloud infrastructure.
The energy consumption of storing one terabyte for one year
The German agency's study details the analysis of four different data centres, examining the environmental impact of each component from the moment of manufacture, taking into account the partial allocation of server resources to data storage and their energy consumption.
On average, storing 1 TB for one year consumes 3,634 MJ, or 1,009 kWh.
The impact of the data centre's location
Applied to the German energy mix (366 gCO₂e/kWh), this leads, for example, to an emission factor of 210 kgCO₂e/TB/year.
The Microsoft 365 service is located (for legal reasons) in Europe, without specifying the exact country. It is preferable to apply an average European energy mix, i.e. 242 gCO₂/kWh in 2023 (source: European Electricity Review).
The impact of data replication
To ensure the OneDrive or SharePoint service, Microsoft announces that it replicates data three times in the same data centre. This can increase to six replications for large companies using replication across multiple zones.
OneDrive is based on Azure Blob Storage, which offers several levels of replication:
- Locally Redundant Storage (LRS): three copies in the same data centre.
- Zone Redundant Storage (ZRS): three copies in separate availability zones within the same region.
- Geo-Redundant Storage (GRS): six copies (three in one main region + three in another region).
Emissions factor for storing one terabyte for one year on OneDrive or SharePoint
In summary, storing one terabyte for one year will consume 3,634 MJ, or 1,009 kWh. On average, one kWh of electricity emits 242 gCO2e. And this useful terabyte on Microsoft 365 is replicated three times. 1,009 kWh x 242 gCO2e/kWh x 3 = 732 kgCO2e
1 TB on OneDrive, SharePoint, Teams, and Exchange emits 732 kgCO2e/year for Microsoft 365 usage in Europe.
Data flow emissions factor
It is also difficult to give a precise value for CO2 emissions from data flows because there are very significant differences depending on the transmission methods used.
Overall, Internet use has a carbon footprint ranging from 28 to 63g of CO2 equivalent per gigabyte (GB).
In France, -86% of the median value of 32 gCO2e/GB, or 5 gCO2e/GB
Sources:
- German Federal Environment Agency (Original in German) : https://www.umweltbundesamt.de/sites/default/files/medien/5750/publikationen/2021-06-17_texte_94-2021_green-cloud-computing.pdf
- Article from Stanford Magazine : https://stanfordmag.org/contents/carbon-and-the-cloud
- Etude “The The overlooked environmental footprint of increasing Internet use“ : https://www.sciencedirect.com/science/article/abs/pii/S0921344920307072?via%3Dihub
- European Electricity Review 2024 : https://ember-energy.org/app/uploads/2024/10/European-Electricity-Review-2024.pdf
- SharePoint and OneDrive data resiliency in Microsoft 365 : https://learn.microsoft.com/en-us/compliance/assurance/assurance-sharepoint-onedrive-data-resiliency
Azure Storage redundancy : https://learn.microsoft.com/en-us/azure/storage/common/storage-redundancy