The spreadsheet includes a number of administrative tabs which are there to support the carbon calculations and you may never need (or want) to edit or view these. These tabs are briefly described below:

• Datasheet - you will find some assumptions documented here as well as some proxy values that are used in the tool. Do feel free to add any additional assumptions you have made.

• Grid factors - this tab contains samples of emissions intensity factors for electricity generation in different countries. These figures are used to carry out calculations within the tool. If you find that your country doesn’t appear on the list, you may add data for your country to the list (with a reference to the source). Alternatively, if no reliable source of data can be found, you can use the ‘Other countries’ option (which uses an averaged figure as an estimate).

• Cloud factors - proxy data is provided in this tab for AWS, Google Cloud Platform and Microsoft Azure. These figures are used to carry out calculations within the tool.

• Read me - this tab includes some further information about the purpose of the tool, disclaimer text and further reading about the DIMPACT methodology on which it was based.

Note that the data in the Grid Factors and Cloud Factors tab will change over time. This will be updated in the spreadsheet template as it becomes available to us.

If you would like to use the tool to track the carbon emissions of the organizational travel that supports your digital preservation work, you can do so using the Travel tab.

There are many tools available online which you can use to generate figures for flights, train or car travel. The list below isn’t exhaustive – they all have their pros and cons. and some are focused on a particular mode of transport or stronger for a particular geographic area.

You might like to try and few out and compare the results – where they differ you may find you can to dive into the methodology that sits behind the tools (you should find this described on the website) to better understand the differing assumptions that the figures are built upon and think about which you trust the most.

Suggested tools to try out include the following, but you may find others that you prefer:

• SCIF’s Travel Carbon Calculator can provide an estimate for different types of travel which you can then enter into the calculation tool.

• ICAO Carbon Emissions Calculator (ICEC) is a helpful tool for calculating the carbon cost of flights.

• BlocCarbon’s Travel Carbon Calculator calculates the cost of flights, train journeys, buses, cars and taxis and uses the UK government's DESNZ 2026 conversion factors. This tool allows you to build up multimodal journeys (involving different forms of transport) but may be better for journeys starting or ending in the UK.

• World Land Trust Transport Calculator covers a wide range of transport, including flights, cars, trains, buses/coaches, and ferries.

• EcoPassenger is a good option for rail travel, particularly in Europe. It calculates the environmental impact of actual station-to-station journeys across Europe rather than relying on a generic distance-based rail figure.

Whichever tool you choose, it is important to note the unit of measurement used. The Carbon Footprint Calculation Tool will take figures in tonnes of carbon dioxide equivalent (tCO2e) or kilograms of carbon dioxide equivalent (kgCO2e) – you only need to enter a value in one of these columns not both. If you enter a figure in tCO2e the spreadsheet will convert this to kgCO2e for you.

This tab calculates allows you to better understand the carbon footprint of end users interacting with your digital content. A surprising amount of carbon can be generated by end users and their devices, so this tab aims to estimate the impact of users discovering and downloading content on your website. You will enter annual statistics about the use of your website here and calculations will be made within the spreadsheet on the carbon footprint of its use, based on the estimates and averages which are noted in the spreadsheet.

This tab is the place to record information about the data transmitted via the network. This should include traffic between service machines and significant uses of the network. The RAM headings from the Service Map are included in this tab for reference but do use these flexibly and edit them if they are not helpful. You may add as many rows as necessary under these headings to capture the different activities you are measuring. Do however check that the cells that sum up the totals are referencing all the necessary columns and that the right totals are being pulled into the summary tab.

Use this tab to enter data about the activities/machines/data centres that are hosted in the cloud. If you have a hybrid service (i.e. part on-site and part in the cloud) tease apart the data as best you can. For each cloud service provider, request a carbon report. Note that these reports are rarely very granular and often will provide you with annual or monthly figures without much explanation or context, so it is unlikely you will be able to break these figures down into specific digital preservation activities. Remember that you will need to indicate a greater level of uncertainty about how these figures have been calculated in the ‘data confidence’ column of the spreadsheet.

• Be careful about the unit of measurement in the report you have been given as this may need to be translated to kgCO2e/year for entry into the tool.

• Cloud providers may bundle embodied carbon into the figure they provide. Embodied carbon describes the emissions from manufacturing, transporting, and disposing of hardware (though important, these are out of scope for this toolkit). If it is possible to separate these out, then do so before entering your data. Do not worry if this is not possible – just make a note in the Notes field.

• Some cloud providers (for example AWS) may ask you to choose between two methods of estimating carbon footprint:

  • LBM (Location Based Method)

  • MBM (Market Based Method)

If you are unsure on which method to select, we recommend LBM as it measures emissions based purely on the average carbon intensity of the physical grid where your energy is consumed.

• The spreadsheet is set up to allow you to enter data for one cloud provider for data centres/servers and one for networking.

  • If you only have one provider, that is not a problem, just enter your data into the relevant row and leave the other blank.

  • If you have more than one provider for either of these areas of activity, you may adapt the spreadsheet to add additional rows. Note that you will also need to adapt the summary tab to ensure it adds up the total from all the providers you have entered.

The summary tab is really the most important tab of the spreadsheet. It brings together and totals up all the calculations that have been made on the other tabs. Once you have entered your data into any of the spreadsheet tabs described below, your carbon footprint calculation will automatically display in the summary.

Benefits of the summary tab include:

• It calculates an overall figure of your carbon footprint, adding up all the totals from the other spreadsheet tabs.

• It provides an easy way for you to compare the figures from specific areas of your digital preservation work.

• It provides a summary view into the data which you can share with colleagues, who may not need to understand all the details of how the figures were calculated.

In most cases you shouldn’t need to edit anything on the summary tab, though reasons why you might include:

• You may need to amend labels or headings in the summary tab if you have adapted any of the spreadsheet sections to record your data in different ways (for example changing or combining the RAM headings).

• If you have asked colleagues or service providers to gather information for you and they have given you a final total rather than the individual figures needed to populate the spreadsheet tabs, you may add these straight into the summary.

Perfection is the enemy of the good here. Not all data are equal, and spending a lot of time and energy gathering really detailed data might contribute more to your carbon footprint than it would ever save.

Prioritize the most significant digital preservation activities or product/service for your organization. Focus on measuring those activities that you think might utilize the most hardware and/or energy. Note that the NDSA Levels of Digital Preservation Environmental Sustainability Guide provides some helpful guidance on which areas of digital preservation activity have the most impact. You can then fine tune your calculations by focusing on less significant activities as time allows.

There is some data you’ll need to gather within your organization, and some data that you’ll need to ask cloud service providers to provide. In larger organizations, there may also be internal virtual clusters or clouds. You may need to consider installing electricity monitors on key devices to gather the data. You may need to ask IT colleagues to do this for you. Any internal advocacy work you have done may help move things forward – review the Getting organizational buy-in section for a refresher.

If you can’t gather the relevant data, you will need to estimate or use a proxy. Remember to record the source of the information and how confident you are in this data. The calculation tool provides space to record this information, and this can be helpful when interpreting and reporting on the calculations. Note that we have also provided some helpful proxy information in the calculation tool.

Entering your data

Now it's time to populate the Carbon Footprint Calculation Tool. Remember you may fill out as much or as little of the spreadsheet as you wish. Do not feel you have to tackle every one of the sections (or spreadsheet tabs) in order to find out something meaningful. Carrying out this work takes time, energy and collaboration so take it one step at a time, starting with a specific task or goal, and building out as confidence and/or capacity grows.

• Try not to be overwhelmed by the size or complexity of the spreadsheet. You do not have to tackle everything at once. Remember you are encouraged to start small and build up. For inspiration, see how members of our Carbon Calculation Support Group tackled the challenge in the Case Studies section.

• As you start using the Calculation Tool you will notice there are some cells you are meant to enter data into and others that contain formulae to generate values for you. As a general guide, you’ll enter data in columns or rows with a light green shading, and the tool will calculate numbers in the columns or rows with a light purple shading. The guidance provided for each of the spreadsheet tabs describes only those fields that you enter data into.

• The spreadsheet tool does lots of the work of generating carbon footprint calculations for you. Once you have gathered your data and entered it into the right columns, the calculations will happen automatically, drawing from data held in the administrative tabs and formulae within the spreadsheet cells. Take care if copying and pasting data into the spreadsheet that you are not overwriting values that are not intended to be edited.

• Keep an eye on units of measurement – these are recorded in the column names. Substantial errors can occur if the figures you enter are using a different unit of measurement.

• The tool has been set up to report annual figures. If you are collecting monthly figures, then multiply these up 12 before entering them into the tool. If you are collecting daily figures, then multiply these by 365 before entering them into the tool.

• Recognise that the figures you get from carrying out a carbon calculation exercise will never be 100% accurate. Accept the fact you may have to rely on assumptions and estimates and try and report the associated uncertainty and data quality in a transparent manner using the fields provided.

  • Distinguish between data gathered from direct measurement (e.g., monitors attached to equipment), and data based on estimations or proxy data.

  • Describe your confidence in the data, estimate, or proxy by choosing an appropriate descriptive term from the drop-down menu (e.g., high, medium, or low).

• We have seen at least at least one instance of a community member not being able to open the spreadsheet on devices managed by their organization. Opening the spreadsheet produced a series of error messages relating to the formulae and references within the tool. Given the spreadsheet opened with no issues on personal devices, this was diagnosed as a local IT configuration issue that could only be resolved by working with IT colleagues to troubleshoot. This is another reason why you may need to have colleagues in IT on side with your carbon calculation work. The Getting organizational buy-in section may be worth revisiting.

• The spreadsheet tool is designed to be a starting point but may not fit with all possible use cases. Do treat it as a flexible tool that can be adapted to meet your needs – for example you may wish to add rows or edit headings. A little bit of expertise in Excel may be needed to ensure the calculations still work as expected and that the right totals are pulled into the Summary, so do double check that things are working as expected.

• Check you have the latest version of the spreadsheet. The version number of the tool should be in the filename when you download it and the date it was last updated appears on the summary tab. Compare this with the current version number as listed on the front page of this toolkit to see if you have the latest version.

• If you find a bug or error in the spreadsheet tool, please do let us know (infoATdpconlineDOTorg) so we can fix it.

Start by creating a map of your organization or the product/service you are focused on for carbon footprint calculation. It is particularly important to understand your organizational boundaries and identify the points where content and hardware enters and leaves your care, as this will define the scope of your carbon footprint calculations.

To get you started, we’ve created a generic model that is aligned with the service capabilities of DPC’s Rapid Assessment Model (RAM):

A high-level functional service map of a generic digital archive (see the text below for a fuller description of each of the elements that make up this map)

The purple boxes in the diagram above represent the preservation services you provide and are aligned to the five service capabilities of DPC RAM. Some archives perform all these functions in-house and some will use cloud-based service providers to manage certain workflows or for storage. The way these functions are performed will impact the way you gather data in the next step. The contents of each box are unpacked further below.

Upstream activities

Content Provider:

• Activities you may carry out within this section that will have a carbon footprint include: content creation, digitization, metadata, delivery via FTP, web serving.

Hardware Manufacturer:

• The manufacture of hardware that is used for digital preservation activities.

Digital preservation activities (aligned with DPC RAM)

Acquisition, Transfer and Ingest:

• In DPC RAM this is described as ’Processes to acquire or transfer content and ingest it into a digital archive’.

• Activities you may carry out within this section that will have a carbon footprint include: donation and depositor management, contracts and billing, pre-ingest appraisal, authentication, downloading, file transfer services, integrity checking, web crawling, unpacking, appraising, file identification, virus checking, ingest, copy backup, normalizing, extraction of metadata, transforming, re-appraisal.

Bitstream Preservation:

• In DPC RAM this is described as ‘Processes to ensure the storage and integrity of digital content to be preserved’.

• Activities you may carry out within this section that will have a carbon footprint include: content storage (in multiple locations), integrity checking, repair of corrupt files.

Content Preservation:

• In DPC RAM this is described as ‘Processes to preserve the meaning, usability and functionality of the digital content over time’.

• Activities you may carry out within this section that will have a carbon footprint include: file format identification, file format validation, creation of preservation metadata, testing and quality checking of preservation actions, logging and monitoring, system analytics, file format migration, emulation, reporting.

Metadata management:

• In DPC RAM this is described as ‘Processes to create and maintain sufficient metadata to support preservation, discovery and use of preserved digital content’.

• Activities you may carry out within this section that will have a carbon footprint include: the extraction, creation, management, storage, updating, and supplying of metadata.

Discovery and Access:

• In DPC RAM this is described as ‘Processes to enable discovery of digital content and provide access for users’.

• Activities you may carry out within this section that will have a carbon footprint include: preparation of access copies, content management system, servers, user interface, search, advanced access and visualization tools, load balancer, public access terminals, helpdesk, user analytics, virtual exhibitions, access statistics and reporting.

Downstream activities

Content delivery network:

• A distributed service that provides rapid and reliable access to content depending on the location of users so that Internet traffic is managed and users have similar access irrespective of distance. They can be used for all manner of content but are particularly associated with on-demand streaming media and social media platforms.

End Users:

• Equipment in use by the users of the digital content (e.g., desktops, laptops, smartphones, tablets), bots and AI, printing, saving to USB for onward use.

Setting scope

Calculating your carbon footprint means gathering data, so it is helpful to start with a manageable or meaningful task or existing data sources. Plan and scope your work carefully. It may be easiest to focus on your use of electricity, for example, or a particular aspect of your digital preservation activities such as integrity checking. Even if your organization is required to report formally on its entire carbon footprint (including other areas of impact such as staff travel), begin from a realistic and manageable starting point rather than trying to map and measure everything at once.

Defining goals

Before you start, it is important to clarify your goals and think about how you plan to use your carbon calculation. Here are some possible options for you to consider:

• Informal, high-level scoping – “we just want a sense of the scale of our carbon footprint, and which aspects of our service or organization generate most carbon”.

• Corporate reporting – “we want to work towards reporting our carbon footprint in a way that is aligned with the Greenhouse Gas Protocol so that we can report on our Scope 1, 2, and 3 emissions”.

  • Scope 1 – direct emissions – emissions your organization is directly responsible for. These are the ones you have most control over.

  • Scope 2 – indirect emissions – e.g., electricity use

  • Scope 3 – everything else in your supply and value chain – These include upstream activities such as purchased goods and services, including cloud storage, fuel and energy purchases (petrol), transportation of goods or hardware, business travel, employee commuting. Also downstream activities such as processing of finished goods, use of your services, end-of-life treatments.

• Product/service reporting – “we want to report to depositors/users/stakeholders on the carbon footprint of our digital preservation services; for example, so that a particular donor or depositor we work with understands the carbon footprint of preserving their content”.

• Target setting – “we’ve established our current carbon footprint, and now want to set reduction goals and then recalculate our carbon footprint periodically to monitor whether we are achieving our goals”.

• Modelling impact of change or decision – “we are exploring potential operational changes and want to assess what effect a particular change would mean in practice for our carbon footprint”.