Microsoft Outlook vs Slack

This comparison uses the current IdleForest model for Microsoft Outlook and Slack: their category, modeled CO2 per use unit, methodology notes, key drivers, and assumptions.

Supporting comparison page

Microsoft Outlook

Work

10g

CO2 / HOUR

Slack

Work

30g

CO2 / HOUR

Higher emissions

Data-backed comparison

Summary

When comparing Microsoft Outlook and Slack, Slack generates significantly more CO2 emissions per hour (30g) than Microsoft Outlook (10g). Both applications rely on devices, networks, and server infrastructure, which all contribute to their environmental impact.

Why the gap happens

Slack is modeled at 30g CO2 per unit, while Microsoft Outlook is modeled at 10g, so the visible gap is 20g in the current dataset.
Both products sit in the Work category, so the difference comes from the per-product estimate and page-level methodology fields rather than a category change.
The estimate treats Slack as an active work tool with a lower hourly footprint than video meetings, but higher overhead than a static page because it stays synced across devices and workspaces.
Video, screen sharing, and participant count all change the intensity of online work tools.

What to act on first

Because Slack is higher in the current model, start there: Turn video off when it is not necessary for the meeting outcome.

Slack is currently modeled at 20g CO2 more per unit of use than Microsoft Outlook.

Deep dive into their footprints

Read the full Microsoft Outlook report Read the full Slack report

Comparison takeaways

Slack is modeled at 30g CO2 per unit, while Microsoft Outlook is modeled at 10g, so the visible gap is 20g in the current dataset.

Both products sit in the Work category, so the difference comes from the per-product estimate and page-level methodology fields rather than a category change.

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