According to Neowin Storage Sense will be available on Windows 9 too, just like it is on Windows Phone. With storage sense you’re able to see what apps and files take up your internal and external storage space. It would be a very nice addition because there’s no such feature on previous versions of Windows. In Windows 8 it was already possible to view how much space your apps take, but with storage sense you’ll be able to see a more detailed overview of your storage.