Measure the electricity consumed by a browser to r

Is there a way to calculate the electricity consumed to load and render a webpage (frontend)? I was thinking of a 'test' made with phantomjs for example:

load a web page
scroll to the bottom

And measure how much electricity was needed. I can perhaps extrapolate from CPU cycle. But phantomjs is headless, rendering in real browser is certainly different. Perhaps it's impossible to do real measurements.. but with an index it may be possible to compare websites.

Do you have other suggestions?

It's pretty much impossible to measure this internally in modern processors (anything more recent than 286). By internally, I mean by counting cycles. This is because different parts of the processor consume different levels of energy per cycle depending upon the instruction.

That said, you can make your measurements. Stick a power meter between the wall and the processor. Here's a procedure:

Measure the baseline energy usage, i.e. nothing running except the OS and the browser, and the browser completely static (i.e. not doing anything). You need to make sure that everything is stead state (SS) meaning start your measurements only after several minutes of idle.
Measure the usage doing the operation you want. Again, you want to avoid any start up and stopping work, so make sure you start measuring at least 15 seconds after you start the operation. Stopping isn't an issue since the browser will execute any termination code after you finish your measurement.

Sounds simple, right? Unfortunately, because of the nature of your measurements, there are some gotchas.

Do you recall your physics classes (or EE classes) that talked about signal to noise ratios? Well, a scroll down uses very little energy, so the signal (scrolling) is well in the noise (normal background processes). This means you have to take a LOT of samples to get anything useful.

Your browser startup energy usage, or anything else that uses a decent amount of processing, is much easier to measure (better signal to noise ratio).

Also, make sure you understand the underlying electronics. For example, power is VA (voltage*amperage) where both V and A are in phase. I don't think this will be an issue since I'm pretty sure they are in phase for computers. Also, any decent power meter understands the difference.

I'm guessing you intend to do this for mobile devices. Your measurements will only be roughly the same from processor to processor. This is due to architectural differences from generation to generation, and from manufacturer to manufacturer.

Good luck.