Water fountains, maybe they can work from just pouring water into it with a bucket and then be able to turn it on and off. I suppose we don't need to over think realism so much.
Maybe a piping system to move water here and there.
Air conditioners for houses built in the hell regions which would make a sealed off construction be comparably cooler. If a door is open or a window is not sealed with glass then it would not work. Perhaps construction could be using: 50 Aluminum sheets, 10 iron sheets, 5 tungston wire, 1 circuit board.
Ability to plant flowers and other bushes.
Ability to add spin functionality to constructions, requires circuit board. Can set axis, spin speed and direction. Perhaps have a limit of spinnable constructions per area.
Flags that slowly flap in the wind. A long triangle type of flag that you can put a color too, and a rectangle flag that you can put an image onto.
Spot lights with an adjustable cone falloff.
Sell blueprints in game.