> Software and IT are full of these [small wastes, easily avoidable or without real benefit], and the total amount of energy wasted is enormous. But every single developer thinks that in comparison, it's practically nothing.

I mean, are they wrong? Think of it this way: A phone running 24/7 at 100% CPU will draw, what, maybe 20W at most? That's 1/5 of an old light bulb, of which many still remain.

But the phone isn't running at 100% CPU all the time. It takes literally less than a second to render the CSS, and 20x less power than a desktop PC would've used just a couple decades ago. In exchange, that's creative work for someone, a (hopefully... not always) better design for the user, and some value for the business behind it all.

On a output/watt basis, that's probably MORE energy efficient than most creative human endeavors. How much energy does it take to make a single ceramic cup? A piece of steel art? A watercolor that takes raw materials from around the world made in different factories, several hours/days/weeks to paint under artificial lighting and climate controls, etc.?

If software is a wasteful form of human energy use, well, probably most things are, and at orders of magnitude worse.

I don't know what's easily avoidable or wasteful about CSS: it's literally the most basic way of formatting a webpage. Is Markdown or a Word doc similarly wasteful? I bet either is less optimized than plain HTML + CSS. What's the alternative here? Plaintext web pages? Gopher? They're not going to save meaningfully more energy. Phones idling and waiting for the next cell tower message are going to use more power than processing some CSS. Literally powering the LED screen takes more power.

At the micro scale, generational improvements in energy efficiency gained from improved semiconductor processes more than offset any incremental loss from a slightly more complex CSS selector -- by this I mean you can compare the power usage of a old desktop rendering a HTML 1.0 webpage with any budget cell phone today rendering a modern webpage. The latter is going to use much much much much less power, despite all the CSS and frameworks and cloud services and whatever.

There are some things that are worth optimizing, like maybe data center power and cooling draws. But at the level of the CSS on an individual webpage? It's not worth wasting brainpower on. You probably waste more calories (and thus fuel input for human metabolism) just thinking about the problem than anything you'd save from solving it...

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edit: I'm reminded of https://solar.lowtechmagazine.com/power/, a site that's always annoyed me because it's so much virtue signaling with so little actual virtue. The amount of energy infrastructure it takes to individually power a website like that out of someone's backyard, the time it takes to dither the images, the battery maintenance... it's so pointless, all just to serve a few HTML pages at 2W. 2W for a site that small? It would use LESS power in a proper data center, statically cached at a CDN alongside a billion other files.

I don't know why there is this movement towards pretend-optimizing irrelevant things, but IMO they are a total distraction (or at best an artistic inquiry), not real power optimizations or climatic solutions. I think it annoys me because there are so many REAL problems (and real solutions!) that need our collective attention. That annoyance isn't directed at you, just general angst about the state of the world lol