A digital artwork consumes electricity in the exhibition space, on servers, across the network and on the public's devices. It also carries impacts from manufacturing, transport, cooling, replacement and waste. Adding up the estimate for a web page and calling it the 'footprint of the artwork' leaves out almost everything else.
This guide sets out how to define the boundaries, measure and estimate without false precision. It is not an audit, a certification or a conformity assessment. The figures for two artworks are comparable only if they share scope, method and unit.
What you want to measure
You may measure or estimate, separately:
- power and energy during an exhibition;
- estimated operational emissions;
- consumption per visit, per hour or per execution;
- manufacturing and renewal of equipment;
- data transfer and storage;
- operations on a blockchain, if the artwork uses them;
- production, transport and dismantling.
Do not combine kWh, kg of CO2e, transferred data and waste without explanation. These are distinct magnitudes.
Functional unit and system boundaries
The concepts in this section derive from the life cycle assessment framework of the ISO 14040 and ISO 14044 standards. These are paid standards and have not been read in their entirety for this guide; they are therefore explained here in operational terms without reproducing their definitions.
- Functional unit: the quantified reference against which the result is presented, for example a 30-day exhibition, one hour of operation, one thousand visits or one year of hosting.
- System boundaries: the processes and components you include and those you exclude.
- Embodied emissions: those associated with the production and manufacturing of equipment and infrastructure, delimited according to the method you employ.
Declare what is included and what is left out. Record the location and dates as well, because the carbon intensity of electricity changes with both.
An installation powered on for ten hours for ten visitors and another used by ten thousand do not respond in the same way per visit. Publish the total alongside the functional unit: efficiency per visitor does not justify a high total.
Operation in the exhibition space
Measure actual power with a meter or wattmeter whenever possible. Include computer, screen, projector, audio, sensors, network, dedicated cooling and standby mode. Multiply the power by the actual hours of operation, not the theoretical schedule.
Energy (kWh) = average power (kW) × hours of operation. This is an elementary calculation for this guide, not a methodology specific to any source.
Separate use, standby and power-off. Note the model, configuration and measurement method.
Server and hosting
Request consumption data, region, electricity mix, cooling, scope and embodied emissions from the provider. If they do not provide them, declare that you are using an estimate and specify which one.
CPU, GPU, memory, storage and redundancy change the result. 'It is in the cloud' does not describe an infrastructure.
Network and data transfer
The volume of data transferred serves as an approximation, not as a direct measurement of all energy involved.
The Sustainable Web Design Model (SWDM) is an open methodology that estimates emissions from data centres, networks and user devices, separating operational emissions from embodied emissions at each stage. Version 4 is the one currently described by the Sustainable Web Design project. It takes data transfer as its primary variable and relies on hypotheses declared by its authors: its broad boundaries likely overestimate actual emissions and the source data present discrepancies.
In the comparisons published by The Green Web Foundation, version 4 produced estimates approximately two-thirds lower than version 3. This difference arises from the change in methodology and data. It does not indicate that an artwork emits less.
CO2.js is a library maintained by The Green Web Foundation and distributed under the Apache 2.0 licence. It receives transferred bytes and returns an estimate of the emissions associated with moving them over the internet. It does not measure all energy or the entire footprint of an artwork.
Always indicate the model version, date, bytes, visits, cache usage, region and the factors applied.
Public devices
If the artwork is viewed on each visitor's phone, computer or screen, those devices remain outside your control. Decide whether to include them. If you do include them, declare which hypotheses you use regarding usage time and equipment.
The SWDM accounts for the operational and embodied parts of user devices separately. There is no universal method for attributing the footprint of third-party devices to a specific artwork.
Manufacturing and equipment replacement
For certain devices and service life scenarios, manufacturing may represent a larger portion of the climate impact than direct electricity consumption during use. A life cycle assessment of a smartphone published by Ericsson in 2016 illustrates this for that model, with average usage and a three-year service life, excluding network and data centres: it attributed the majority of the climate impact to production. This is an example limited to that device and that scenario.
Do not generalise this relationship to every computer, screen, projector or installation: it depends on the equipment, the service life and the hours of use.
Do not charge the entire manufacturing of a piece of equipment to one exhibition without an allocation rule. Declare the expected service life, the percentage of use, subsequent reuse and the final destination.
These measures are proposals from this guide, not results from any source:
- reducing purchases and extending the life of equipment;
- repairing, sharing and documenting equivalencies;
- avoiding replacements without justification.
Such measures are usually more robust than replacing equipment for minor gains in operational consumption.
External services
Inventory the third-party services the artwork consumes: application programming interfaces, fonts, video, maps, analytics, storage, or remote processing. Request consumption and regional data from the provider. If unavailable, declare the service as excluded or estimated, rather than zero.
Blockchain
Identify the network, date, layer, operation type and consensus mechanism. Do not use Ethereum figures from prior to the transition to proof-of-stake in September 2022 to describe the current network.
The ethereum.org page on energy consumption (updated, by its own account, on 28 July 2026) provides an estimate of approximately 0.0026 TWh per annum for the entire proof-of-stake Ethereum network, which is 2,601 MWh. It attributes this to a September 2022 study by the Crypto Carbon Ratings Institute (CCRI), which this guide has not read in its entirety. The page itself clarifies that these are estimates based on public data rather than an official statement from the Ethereum Foundation, and that the figure fluctuates according to the number and configuration of nodes.
This is a figure for the entire network under that methodology. It is not equivalent to the consumption attributable to a single token or transaction, and this guide does not offer per-transaction estimates.
For Tezos, no current, accessible, and sufficiently documented primary estimate of the total network energy consumption has been located for this review. Consequently, this guide includes no figures.
Do not compare the annual energy of one network with that of an operation on another without explaining the allocation. The guide How OBJKT works distinguishes between token, platform, file, and chain.
Electricity carbon intensity
Electricity emissions depend on the electrical system, the time and the generation technology. Red Eléctrica provides factors and emissions by time interval, system and technology, expressed in t CO2 eq/MWh, with hourly detail and a methodological note. The specific period depends on the query performed. This is the primary source for artworks exhibited in Spain.
The SWDM applies a global average intensity by default. If the location and date of operation are known, replace this value with a specific one and declare the change.
Record:
- country or electrical system;
- date and time;
- applied factor and unit;
- source and date of consultation;
- whether the data is hourly, annual, or approximate.
Do not present an annual factor as if it were hourly. Furthermore, do not use the national mix as if it described the contract of a specific supplier.
Calculation and confidence level
Classify each data point:
- measured: meter or attributable invoice;
- reported: data provided by the supplier;
- estimated: result of a model with hypotheses;
- not located: insufficient data.
Do not mix figures without marking their origin. Retain calculation files and factor versions. Avoid decimals that exceed the precision of the inputs.
SCI for Web, from the Green Software Foundation, is a draft sectoral extension for web applications based on the ISO/IEC 21031:2024 standard. It is not yet an approved standard. The ISO/IEC 21031:2024 (Software Carbon Intensity, SCI) standard has been published since March 2024; its full text is subject to payment and this guide has not read it in its entirety.
Communicating results
A brief report should declare:
- object and period;
- functional unit and boundaries;
- measured data;
- reported data;
- estimates and tool, with version;
- electricity factors;
- embodied hardware and allocation rule;
- exclusions;
- uncertainty;
- reduction measures.
Do not use 'neutral', 'green', or 'zero' without indicating scope and evidence.
Directive (EU) 2024/825 regulates commercial practices towards consumers. It addresses generic environmental claims, with examples such as "green", and prohibits certain climate assertions based solely on offsets. It may be relevant if an artwork's footprint is used to sell or commercially promote it. It does not, by itself, impose a measurement method on every artwork or technical specification. The full transposition in Spain has not been located as of the revision date.
These reduction measures are proposed by this guide:
- reduce operating hours and standby mode, and switch off equipment outside necessary hours;
- reuse and extend the life of hardware;
- size equipment and servers to the requirements of the artwork;
- compress without altering the essential properties of the artwork;
- use cache and local processing where appropriate;
- choose a region and provider with verifiable data;
- eliminate unnecessary transfers, logs, and copies;
- design for maintenance, repair, and end-of-life;
- review climatic and exhibition conditions when the artwork permits;
- measure again after each change.
If you record this data in the technical sheet, the lender and the organiser will know what was measured and how. When the artwork is loaned, the guide on lending technology-based artworks helps to distribute who supplies and powers each piece of equipment. Sufficient installation instructions can prevent technical travel.
Checklist
- The question, period, boundaries, and functional unit are defined.
- Consumption in the exhibition space was measured or estimated separately.
- Server, network, and audience devices were not conflated.
- Manufacturing and service life have an allocation rule.
- Tool, version, and assumptions are stated.
- The blockchain is identified by network and date, without per-transaction figures.
- A distinction is made between measured, reported, and estimated data.
- The electricity factor indicates system, date, unit, and source.
- Uncertainty and exclusions are published.
- Reduction measures respect the properties of the artwork.
- Incompatible methods or versions are not compared.
Further reading
- How OBJKT works: publishing, buying and preserving digital art on Tezos.
- How to prepare a technical sheet for a digital or interactive artwork.
- How to lend a digital or technology-based artwork for an exhibition.
- How to write installation instructions for a technology-based artwork.
Sources
- Sustainable Web Design, Estimating Digital Emissions (version 4). The page does not display a date.
- The Green Web Foundation, CO2.js: Overview, for the library, and Understanding the latest Sustainable Web Design model update, dated 4 June 2024, for the comparison between versions 3 and 4.
- Green Software Foundation, SCI for Web. Project draft.
- ISO, ISO/IEC 21031:2024. Published in March 2024; full text is subject to payment.
- ethereum.org, Energy consumption and CCRI, The Merge. The figure is provided by ethereum.org; the CCRI report is from September 2022.
- Red Eléctrica, CO2 emissions associated with electricity generation. The period depends on the query.
- Ericsson, Life cycle environmental impacts of a smartphone. September 2016; a specific phone model and scenario.
- BOE (OJEU), Directive (EU) 2024/825. Dated 28 February 2024.
Status: Verified. Revision: 11 October 2026. General information on how to delimit and estimate an environmental footprint; this is not an audit or a certification. If you identify an error, please contact me.