Would it be possible to use a UV protection film on your windows to keep the mats looking spiffy if you do decide to replace them?
Don't think it was natural sunlight UV that did that in the old lab - the old lab had no windows!
I DO have a window in the spare room I use as an office and workshop, AND it is positioned such that all the light comes in from one side (apart from the artificial light directly overhead, which in my case is all LEDs). My mat is just approaching 3 years old now, so far all I really see are the dust lines if I remove something that's been sitting int he same place for some time, that all just wipes clean. However, who knows what it will look like after it's been 7+ years.