Correct, and computers continue running. I'm referring to the carbon emissions of the development project itself. The faster the development is done, the sooner you can get on with developing other things.

I do not believe that was ever in question.

It's a valid objection to the statement they replied to. Saving developer time does not equate to lower emissions, so it is incorrect to call it a "net win".

Sure and trains burn fuel even when you aren’t using them. But if we look at you carbon footprint it doesn’t seem wise to factor in every single train on the planet in your specific account har because they don’t all air still when you aren’t using them.

When talking about the footprint of a company or a project, then you need to restrict the calculations to the resources they actually use. So if a project uses tools to get a product out quicker that means they’ve spend less human-hours, which have a co2 cost associated with them. Then you can weigh the cost of that tool versus the Human Resources both in a financial sense but also with respect to emissions.