[Mod suggestion] Glass roof

[Warm Rain]

What about a glass roof? You could build a greenhouse...

It is a nice incentive to not build underground, since you won't need a sun lamp for your crops (at least at daytime). On the other hand, some heat is lost due to the bad insulation of glass.

A ventilation system that allows for carbon enrichment (to speed up growth) would be a nice addition.

Cheers!