UsesLevel 3 of 6 useUse, level 3 of 6Used to calculate 19 entries, levels 3, 4 and 6Calculated with 5 entries, levels 1 to 3Database structure 
6Territories
5Organisations
4Occupations and activities
2Machine operations
1Calculation factorsCarry out an AI-assisted web search
The assistant runs 2 searches, reads the 5 pages found, then writes a sourced answer. Projet Celsius estimate.
- "Read 1,000 tokens" accounts for 62% of emissions in this scenario.
- 90% of the calculation rests on database assumptions; it does not measure actual use.
- Out of scope: server manufacturing, model training, the network and the user's device.
Sentence to citeRun an AI-assisted web search, Projet Celsius estimate: 1.3 gCO2e per search, for 2.7 Wh of electricity, servers worldwide (458 gCO2e/kWh).
Breakdown of emissions by item
1.3 gCO2e in total: 2.7 Wh of electricity × 458 gCO2e/kWh (servers worldwide).
Inputs of the calculation
PUE of the data centre, Read 1,000 tokens, Write, with reasoning, Web search (benchmark)
How the calculation is built
A classic search is counted with Google's figure of 2009; reading the pages weighs the most.
Comparison with the other uses
↓ The heaviest use in the topic, "Deep research": 45 gCO2e, 36 times more
Emissions of one use, linear scale, 3 of the 5 uses in the topic, those of the same order of magnitude (at most 25 times between the smallest and the largest value). For calculated values, servers worldwide.
Characteristics
| Unit | 1 search |
|---|---|
| Default location | world, 458 gCO2e/kWh (Ember 2025, life cycle); 11 other locations to choose from |
| Counted | the model reading and writing tokens, and data centre cooling |
| Not counted | server manufacturing, model training, the network and the user's device |
| Status | estimated |
All the characteristics
| Identifier | IA-0209, projetcelsius.com/en/ai/database/IA-0209/ |
|---|---|
| Version | 0.1 of 2 November 2026 |
| Category | Uses, a request to AI |
| Choice of the selected value | database calculation from the entries this one is made of, at the quantities of the unit |
| Sources | calculation of the database |
| Licence | CC BY 4.0 |
Usage parameters
Advanced settings
Result for the chosen case
For a carbon footprint
| Item | purchases of services (GHG Protocol scope 3, category 1); regulatory BEGES, category 4 |
|---|---|
| Quantity | 1 search |
| Factor | 1.3 gCO2e per search, IA-0209 version 0.1, based on the grid at the location (location-based), servers worldwide |
| Total | 1.3 gCO2e · not counted: server manufacturing, model training, the network and the user's device |
Breakdown by item
Quantity, unit value, contribution and nature of the data for each item
| Item | Quantity | Unit value | Contribution | Share | Nature of the data |
|---|---|---|---|---|---|
| Read 1,000 tokens | × 5.31 | 0.32 Wh | 1.7 Wh | 62 % | assumption |
| Web search (benchmark) | × 1.82 | 0.3 Wh | 0.55 Wh | 20 % | assumption |
| Write, with reasoning (without reasoning) | × 0.262 | 0.96 Wh | 0.25 Wh | 9 % | convention |
| PUE of the data centre | × 1.10 on the rest | 0.25 Wh | 9 % | convention |
Entries that use it (19)
Literature search, Autonomous agent, 1 month, Automated monitoring, 1 year, ChatGPT, per day, Office worker, 1 year, Accountant, 1 year, Human resources, 1 year, Executive assistant, 1 year, Communications officer, 1 year, Journalist, 1 year, Developer, 1 year, Graphic designer, 1 year, Customer service officer, 1 year, Salesperson, 1 year, Field-based occupation, 1 year, Secondary school pupil, 1 year, Student, 1 year, Perplexity Pro, 1 year, ChatGPT Business, 1 year and
Sources of the calculation
4 publications, for this entry and those used to calculate it, with the chosen parameters.
The result is calculated by Projet Celsius. The sources below support its uses, its factors and its conversion; they do not all measure this total.
Uses and assumptions
These publications shed light on AI tasks and uses. They do not measure the carbon footprint of the case calculated.
Zhang and Nam · June 2026
HANSEL: Extracting Breadcrumbs from Web Agent Trajectories for Interactive Verification ↗ (new tab)
Role and limits : Zhang and Nam
Author. Yujin Zhang and Daye Nam
What the publication covers. 45 web agent trajectories: 13.16 steps and 6.02 pages visited per task on average
What it does not cover. electricity
Reading by the database. A small sample, which gives the order of magnitude of an agent's steps
Web search with an AI → : Read 1,000 tokens →
The 5 pages found, read by the model, and the question: web agents visit 6 pages per task on average
Scope of the figure used. server, excluding the data centre
Limit. The quantity and the share entrusted to AI are database assumptions, not a measured footprint.
Energy and factors
The references of the selected values and of the entries used in this calculation.
Google · January 2009
Role and limits : Google
What the publication covers. a search, data centre
Reading by the database. Never remeasured
Reference of the selected value
Scope of the figure used. A search, data centre included
Limit. Never publicly remeasured; Google's AI answers are not published
Watershed · Aug. 2026
Estimating GHG Emissions from AI Use: Framework for Corporate-Level Measurement ↗ (new tab)
Role and limits : Watershed
Author. Bistline, Ulissi, Davis, Glidden, Joyce, Li, Mohsenin and Suh (Watershed)
What the publication covers. factors per 1,000 tokens read and written at the server before PUE (host and standby machines included), PUE separate (1.10 for a large operator, 1.56 for an unknown operator)
What it does not cover. clean measurements, the model and the hardware
Reading by the database. Default factors proposed for review (public data as of June 2026); for a large operator, taken from Google's measurement published in 2025 (Elsworth et al.), which already contains the data centre overhead; constant per token, they underestimate long contexts and agents according to the authors
Reference for the variant "Medium model, Watershed default factor"
Scope of the figure used. Default factor for 1,000 tokens read, medium model, large operator, at the server before PUE (Watershed table 2, public data as of June 2026)
Limit. A default value that Watershed derives from Google's measurement (0.24 Wh for the median text query of the Gemini app), with about 500 tokens per query and a written token costing 3 times a read token; Watershed does not give the split between read and written tokens. The 0.24 Wh already include the overhead of Google's data centre (0.02 Wh, 8%): with 375 tokens read and 125 written, the simplest reading, the factor contains it, and the PUE of 1.10 applied afterwards counts it a second time (about 9%). Values proposed for review, final at the next version of the framework
Reference for the variant "Medium model, Watershed default factor"
Scope of the figure used. Default factor for 1,000 tokens written, medium model, large operator, at the server before PUE (Watershed table 2, public data as of June 2026)
Limit. 3 times the reading factor, based on the ratio between writing and reading selected by Watershed (Patel et al., Splitwise, 2024). Same derivation and same caveat as for reading: Google's 0.24 Wh already include about 8% of data centre. Values proposed for review, final at the next version of the framework
Web search with an AI → : Data centre PUE →
The data centre, convention C3
Scope of the figure used. building cooling and losses
Limit. This figure covers part of the calculation; it does not measure the whole entry.
Reference of the selected value
Scope of the figure used. Default factor for a large operator, from the server to the data centre; 1.56 for an unknown operator
Limit. A default value, not a measurement
Conversion into carbon
The source of the electricity factor of the selected location.
Worldwide: 458 gCO2e/kWh, life cycle.
Role and limits : Ember
Author. Ember, Our World in Data
What the publication covers. electricity generation over the life cycle, by country
What it does not cover. guarantees of origin
Reading by the database. The same source for all countries
Conversion of electricity into carbon: worldwide
Scope of the figure used. the production of electricity over the life cycle, including power plant construction and fuels
Limit. An average for the chosen country, not the electricity contract or the data centre of a specific service.
Nature of the data
Published readings, conventions, assumptions
- database conventions 10 %
- Projet Celsius assumptions 90 %
Calculation assumptions
Quantities, nature and source of each assumption
Web search (benchmark) : × 1.82
The 2 searches launched by the assistant, counted as conventional searches; divided by 1.10, as the conventional search already counts its data centre
Read 1,000 tokens : × 5.31
The 5 pages found, read by the model, and the question: web agents visit 6 pages per task on average
Write, with reasoning : × 0.262
The sourced answer (convention C1)
Methodology conventions
With their alternatives
| The standard query | A query counts 100 tokens read and 400 written |
|---|---|
| The data centre | Server electricity is multiplied by 1.10 for the data centre |
| The default location | Without other information, the servers are in the world, at the world average electricity |
| Electricity, location-based, on a life cycle basis | The kilowatt-hour is that of the servers' country, on a life cycle basis, from a single source for all countries |
| Two significant figures | A calculated value is rounded to two significant figures, a published value is reproduced with the precision of its source; the calculation keeps full precision |
| The formula | the sum of what makes up the entry, then CO2e: electricity (Wh) multiplied by the carbon intensity of the server location (gCO2e/kWh), divided by 1,000 |
| Calculate a case without an entry | The formula, the default values and a step-by-step example |
History
Entry in version 0.1 of 2 November 2026, in the database in version 0.4
- 2 November 2026Version 0.1 of the entry, as of the date of its current value.
- 31 October 2026Creation of the database, in its first version (0.1).
