Sustainable Web Design emissions calculator as a spreadsheet

	A	B	C	D	E	F	G	H	I	J	K	L	M	N	O	P	Q	R	S	T	U	V
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2		Implementation of the Sustainable Web Design model with tweaks – in Google Sheets!
3		This implementation of the SWD v4 model is focused on readability.
4		It’s for people who want to cross-check their understanding of the SWD calculation with real numbers.
5		It’s also set up to encourage basing the "Data Cache Ratio" on real measurements, and the "New" and "Return" visitors ratios based on readily-available Google Analytics 4 figures.
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7		Model reference:
8		https://sustainablewebdesign.org/estimating-digital-emissions/
9		Author: Thibaud Colas, Torchbox
10		Date: 2026-04-22 (see CHANGELOG)
11		License: public domain dedication
12		Sustainable Web Design emissions calculator as a spreadsheet by Thibaud Colas is marked with CC0 1.0
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14		Data centers	Networks	User devices		World
15	Allocated energy	22%	24%	54%		458.29	Ember "World" 2025 grid carbon intensity as of 2026-04-22
16	Operational	82%	82%	49%			Source: https://ember-energy.org/data/yearly-electricity-data/
17	Embodied	18%	18%	51%
18	OP Energy intensity	0.055	0.059	0.080
19	EM Energy intensity	0.012	0.013	0.081
20	OP Carbon intensity	256.54	458.29	458.29
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22		Average Emissions per Page View (gCO2e) = ([(OPDC × (1 - Green Hosting Factor) + EMDC) + (OPN + EMN) + (OPUD + EMUD)] × New Visitor Ratio) + ([(OPDC × (1 - Green Hosting Factor) + EMDC) + (OPN + EMN) + (OPUD + EMUD)] × Return Visitor Ratio × (1 - Data Cache Ratio))
23		Energy intensity (kWh/GB) = Energy consumption (kWh) / Data transfer (GB)
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26	Readability-optimized formulas with named ranges. With calculation of data cache ratio and new vs. return visitor ratio based on live site measurements and analytics
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28	tCO2e/year	Data transfer (kB)	Data transfer (GB)	Return data transfer (kB)	Return data transfer (GB)	Views	Active users	New users	gCO2e/pageview	New Visitor Ratio	Return Visitor Ratio	Data Cache Ratio	Green Hosting Factor	OPDC	OPN	OPUD	OP (gCO2e)	EMDC	EMN	EMUD	EM (gCO2e)	OP + EM (gCO2e/pageview)
29	0.0001246319655	300	0.0003	3	0.000003	10000	7000	4000	0.01246319655	36.36%	63.64%	99.00%	100.00%	0.00423291	0.008111733	0.01099896	0.023343603	0.001649844	0.001787331	0.011136447	0.014573622	0.037917225
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31	This formula is the most readable as it uses named ranges, however it doesn’t copy-paste well.
32	Use the formulas below to copy-paste multiple rows in the same sheet.
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37	Copy-paste-friendly formulas (to try different scenarios)
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39	tCO2e/year	Data transfer (kB)	Data transfer (GB)	Return data transfer (kB)	Return data transfer (GB)	Views	Active users	New users	gCO2e/pageview	New Visitor Ratio	Return Visitor Ratio	Data Cache Ratio	Green Hosting Factor	OPDC	OPN	OPUD	OP (gCO2e)	EMDC	EMN	EMUD	EM (gCO2e)	OP + EM (gCO2e/pageview)
40	0.037917225	300	0.0003	300	0.0003	1000000	7000	4000	0.037917225	36.36%	63.64%	0.00%	0.00%	0.00423291	0.008111733	0.01099896	0.023343603	0.001649844	0.001787331	0.011136447	0.014573622	0.037917225
41	184.2861888	389.4623532	0.0003894623532	389.4623532	0.0003894623532	3,743,794,604	0	1	0.04922443892	100.00%	0.00%	0.00%	0.00%	0.005495196965	0.01053071541	0.01427893615	0.03030484852	0.002141840422	0.002320327124	0.01445742285	0.0189195904	0.049224
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43	Scenario: worst case (no green hosting, no data cache)
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45	tCO2e/year	Data transfer (kB)	Data transfer (GB)	Return data transfer (kB)	Return data transfer (GB)	Views	Active users	New users	gCO2e/pageview	New Visitor Ratio	Return Visitor Ratio	Data Cache Ratio	Green Hosting Factor	OPDC	OPN	OPUD	OP (gCO2e)	EMDC	EMN	EMUD	EM (gCO2e)	OP + EM (gCO2e/pageview)
46	0.037917225	300	0.0003	300	0.0003	1000000	7000	4000	0.037917225	36.36%	63.64%	0.00%	0.00%	0.00423291	0.008111733	0.01099896	0.023343603	0.001649844	0.001787331	0.011136447	0.014573622	0.037917225
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