Ask HN: How much electrical power does a virtual machine use?

I recently received an email from my employer indicating that for 'environmental reasons' they will be shutting down Windows virtual desktop machines if they're idle for more than eight hours. I was wondering, assuming that the organisation had capacity for 1000 virtual machines, what would be the power saving (Watts) by shutting down a single idle virtual machine? How would this compare, as a percentage per physical machine, to simply encouraging staff to turn off their physical laptop overnight instead?