Add Ws as unit of energy

[juame]

Breaking change

Proposed change

This PR adds Ws (watt-second) as a unit of energy.

Architecture Decision: home-assistant/architecture#1307

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
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Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request: Add watt-second as unit of energy home-assistant.io#41745
• Link to developer documentation pull request: Add watt-second as unit of energy developers.home-assistant#2861
• Link to frontend pull request:

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[jamesmyatt]

Isn't a "Ws" usually referred to as a Joule ("J")? Are there specific use cases where "Ws" is more common?

[jamesmyatt]

Personally, I'd make this match the "JOULE" conversion implementation. i.e. _WH_TO_J * 1e3.

[juame]

Thanks for your review! 👍
I added _WH_TO_WS since I thought using the same _WH_TO_J might be confusing.
But please let me know if you’d prefer that I use the same constant instead!

[jamesmyatt]

I'm not a maintainer, but I don't see the need to duplicate the constants.

[juame]

Isn't a "Ws" usually referred to as a Joule ("J")? Are there specific use cases where "Ws" is more common?

It's the same, but probably depends a bit on the context. 😇. From ChatGPT:

⚙️ When to use joules (J):
Use J when you’re talking about energy in general, in physics, chemistry, or engineering.
It’s the standard SI unit for energy.

⚡ When to use watt-seconds (W·s):
Use W·s mainly when you want to emphasize the relationship between power and time, especially in electrical or power system contexts.

I guess that in the context of Wh and kWh, people would be more likely to think of Ws rather than J. Therefore, I believe it makes sense to add Ws as an additional unit of energy.

[jamesmyatt]

Can you find some examples in smart homes where "Ws" is a commonly used unit? Don't believe everything that ChatGPT tells you.

[jpbede]

This changes our core entity models and thus requires a approved architecture discussion.

Please open a discussion at https://github.com/home-assistant/architecture/discussions. Provide some context and which core integrations would benefit from this unit of energy.

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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[juame]

Can you find some examples in smart homes where "Ws" is a commonly used unit?

Just one example, the MyStrom API returns Ws. #155132 (comment)

My understanding is that the conversion from Ws to a human-readable format should be handled by the unit_conversion, not directly in the integration code. Let me know if I'm wrong.

This changes our core entity models and thus requires a approved architecture discussion.

Thanks @jpbede , will do!

[jamesmyatt]

I'm just a community member, but I don't think that 1 rare example is enough to add something that's just a duplicate of "J", which already exists. But it's not up to me. But let's transfer this to the architecture discussion.

[Petro31]

I'm in agreement here, I don't see the benefit when we have Joules. A 2 second google of watt second returns joules and that should satisfy anyones needs. The graph would be identical to Ws. It would just show J over time instead of Ws over time.