This is a little trick Tamira found out about and told me. Really useful. To make windows appear lighted at night and not during the days, you just go into the Emissions tab in the Reference Window and set the emission to FXLightRegionInvertLightsWhiterun. You can do this on bigger objects, like entire houses as well. I’ve done it here on each and every one of the single windows, because they’re individual meshes. And poof! Here’s a fancy screenshot of how it works too.
Frontier 
And to get the same effect for the interior windows, set the Emittance to “FXLightRegionSunlight” and you have unlit windows during night and lit windows during daytime – with a slow accomodation during morning and evening time.
It’s a really cool effect. 🙂