UsesLevel 4 of 6 occupation or activityOccupation or activity, level 4 of 6Calculated with 7 entries, levels 1 and 3Database structure 
6Territories
5Organisations
3Uses
2Machine operations
1Calculation factorsApplication built with a coding agent
A small web app built with a coding agent. Projet Celsius estimate.
- "Coding agent hour" accounts for 100% of emissions in this scenario.
- 100% of the calculation rests on database assumptions; it does not measure actual use.
- Out of scope: hosting of the app once online, server manufacturing and model training.
Sentence to citeApp built with a coding agent, Projet Celsius estimate: 12 kgCO2e per project, for 27 kWh of electricity, servers worldwide (458 gCO2e/kWh).
Breakdown of emissions by item
12 kgCO2e in total: 27 kWh of electricity × 458 gCO2e/kWh (servers worldwide).
How the calculation is built
About 40 agent hours, scoping questions, reviews, a few images. The volumes are assumptions.
Comparison with other occupations and activities
Characteristics
| Unit | 1 project : 40 agent hours a day |
|---|---|
| Default location | world, 458 gCO2e/kWh (Ember 2025, life cycle); 11 other locations to choose from |
| Counted | the agent hours, the questions and reviews around them, and the cooling of the data centre |
| Not counted | hosting of the app once online, server manufacturing and model training |
| Status | estimated |
All the characteristics
| Identifier | IA-0330, projetcelsius.com/en/ai/database/IA-0330/ |
|---|---|
| Version | 0.1 of 2 November 2026 |
| Category | Occupations and activities, one person, one year |
| 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
40 agent hours a day, servers worldwide: 12 kgCO2e, 27 kWh.
For a carbon footprint
| Item | purchases of services (GHG Protocol scope 3, category 1); regulatory BEGES, category 4 |
|---|---|
| Quantity | 1 project |
| Factor | 12 kgCO2e per project, IA-0330 version 0.1, using the local grid mix (location-based), servers worldwide |
| Total | 12 kgCO2e · not counted: hosting of the app once online, server manufacturing and model training |
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 |
|---|---|---|---|---|---|
| Coding agent hour | × 40 | 670 Wh | 27 kWh | 100 % | assumption |
| Conversation of 10 exchanges | × 10 | 3.5 Wh | 35 Wh | 0 % | assumption |
| Create an image | × 10 | 3.2 Wh | 32 Wh | 0 % | assumption |
| Have code reviewed | × 20 | 1.3 Wh | 26 Wh | 0 % | assumption |
| Quick question | × 60 | 0.3 Wh | 18 Wh | 0 % | assumption |
| Write a page | × 5 | 0.45 Wh | 2.3 Wh | 0 % | assumption |
Entries that use it
No other entry in the database is calculated from this one.
Sources of the calculation
9 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.
Epoch AI · February 2025
Role and limits : Epoch AI
What the publication covers. the calculation from the hardware and the assumed size of the model
What it does not cover. actual measurements
Reading by the database. A public, transparent calculation
Reference of the selected value
Scope of the figure used. GPT-4o, 500 tokens written, full scope
Limit. A public calculation, from the hardware and the assumed size of the model
Conversation of 10 exchanges → : Re-read from cache →
The context re-read from cache at each turn: the previous exchanges, and the document already in the conversation if there is one
Scope of the figure used. server, convention C4
Limit. The quantity and the share entrusted to AI are database assumptions, not a measured footprint.
Hausfather · Aug. 2026
Role and limits : Hausfather
Author. Zeke Hausfather, The Climate Brink
What the publication covers. intensive personal use of Claude Code, tokens recorded and converted into electricity
Reading by the database. A researcher's personal measurements, not a study
Published observation on uses
Scope of the figure used. Instructions typed by a researcher into Claude Code over 8 weeks of intensive use
Limit. Support for the agent volume of an app project
App built with an agent → : Coding agent hour →
About 40 agent hours for a small web application, i.e. 2 weeks of supervised work; a researcher gave 1,138 instructions to an agent over 8 weeks
Scope of the figure used. agent steps, context re-read from cache, data centre
Limit. This figure covers part of the calculation; it does not measure the whole entry.
Coding agent hour → : Re-read from cache →
The context re-read from cache at each of the 120 steps of the hour: 96,000 tokens, 96% of a call in the median published session
Scope of the figure used. server, convention C4
Limit. This figure covers part of the calculation; it does not measure the whole entry.
Coding agent hour → : Read 1,000 tokens →
The new tokens of each step (files read, command results): 3,600, 3.6% of a call
Scope of the figure used. server, excluding the data centre
Limit. This figure covers part of the calculation; it does not measure the whole entry.
Coding agent hour → : Write 1,000 tokens →
The tokens written at each step, draft included: 900 on average in the published logs
Scope of the figure used. server, excluding the data centre
Limit. This figure covers part of the calculation; it does not measure the whole entry.
Projet Celsius · November 2026
Tokens per word, per line of code and per cell, measured with 7 public tokenisers
Role and limits : Projet Celsius
What the publication covers. 479,888 words from 196 blog articles and their English translation, code from the site and the Python library, a table of measurements; tokenisers of GPT-4o, GPT-4, Llama 3, Gemini (via Gemma 3), Mistral, DeepSeek and Qwen
What it does not cover. the Claude tokeniser, not public
Reading by the database. A measurement on technical texts, figures included; to be repeated if publishers change their tokeniser
Projet Celsius measurement, repeated on request with the public tokenisers
Conversation of 10 exchanges → : Re-read from cache →
Length convention: one page
Scope of the figure used. A report page, headings and paragraphs included: between the 1,500-character sheet (250 words) and a full A4 page in single spacing (about 550 words, at 6.1 characters per word measured on our articles)
Limit. This publication supports the quantity of text or content processed, not its carbon footprint.
Get code reviewed → : Write, with reasoning →
Length convention: one page
Scope of the figure used. A report page, headings and paragraphs included: between the 1,500-character sheet (250 words) and a full A4 page in single spacing (about 550 words, at 6.1 characters per word measured on our articles)
Limit. This publication supports the quantity of text or content processed, not its carbon footprint.
Write a page → : Write, with reasoning →
Length convention: one page
Scope of the figure used. A report page, headings and paragraphs included: between the 1,500-character sheet (250 words) and a full A4 page in single spacing (about 550 words, at 6.1 characters per word measured on our articles)
Limit. This publication supports the quantity of text or content processed, not its carbon footprint.
Energy and factors
The references of the selected values and of the entries used in this calculation.
Role and limits : Google
What the publication covers. chips, host, standby machines, data centre, on-site water
What it does not cover. manufacturing, training
Reading by the database. The only production measurement published by a provider
Reference of the selected value
Scope of the figure used. Median of a text prompt; chips, host, standby machines, data centre
Limit. The only production measurement published by a provider, not audited by a third party
Luccioni et al. · October 2024
Role and limits : Luccioni et al.
Author. Luccioni, Jernite and Strubell
What the publication covers. GPU, processor, memory
What it does not cover. data centre
Reading by the database. Open models only
Create an image → : Generate an image →
One image, of the chosen size: standard by default
Scope of the figure used. GPU, processor, memory; excluding the data centre
Limit. This figure covers part of the calculation; it does not measure the whole entry.
Reference for the variant "Standard image, from 512 to 1,024 pixels per side"
Scope of the figure used. Average of the open models tested, 1,000 images; median 1.35 Wh, maximum 11.49 Wh
Limit. Open models only; closed generators publish nothing
Microsoft Research · 2026
Estimation de l'énergie des requêtes en production (Joule) ↗ (new tab)
Role and limits : Microsoft Research
Author. Microsoft Research, Oviedo et al.
What the publication covers. H100 nodes, production
Reading by the database. Calibrated on production
Reference of the selected value
Scope of the figure used. Median, 500 tokens read and 300 written, H100 nodes
Limit. Not a measurement, but calibrated on production; judges public estimates to be 4 to 20 times too high
OpenAI · June 2025
Role and limits : OpenAI
Author. Sam Altman, OpenAI
What the publication covers. an average query
What it does not cover. method, scope
Reading by the database. One sentence, no method
Reference of the selected value
Scope of the figure used. "An average query", with no published method
Limit. No published scope; consistent with Google
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
Coding agent hour → : 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
Quick question → : 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.
Conversation of 10 exchanges → : 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.
Get code reviewed → : 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.
Create an image → : 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.
Write a page → : 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.
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
- Projet Celsius assumptions 100 %
Calculation assumptions
Quantities, nature and source of each assumption
Coding agent hour : × 40
About 40 agent hours for a small web application, i.e. 2 weeks of supervised work; a researcher gave 1,138 instructions to an agent over 8 weeks
Quick question : counted 60 times
About 60 questions on scoping and technical choices
Conversation of 10 exchanges : counted 10 times
About 10 design sessions
Have code reviewed : counted 20 times
About 20 code reviews
Create an image : counted 10 times
About 10 images for the interface
Write a page : counted 5 times
About 5 pages of documentation
Published figures in support
Zeke Hausfather (2026): 1,140 instructions in 8 weeks
Instructions typed by a researcher into Claude Code over 8 weeks of intensive use
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 cache | A token re-read from the cache costs 10% of a token read |
| 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.
- 12 November 2026Calculated value, servers worldwide : 8.1 kgCO2e becomes 12 kgCO2e.Consequence of the new value for the coding agent hour (from 440 to 670 Wh), decided on 12 November 2026; the entry's own data do not change, and its citation carries version 0.4 of the database.
- 31 October 2026Creation of the database, in its first version (0.1).
