Some include floor heating in tiles.
Colder on floor or window.
Because your problem is created by a lack of room for warm heated air to circulate between the floor joists we have to find a way to allow that to happen while maintaining a proper level of insulation.
Hardwood tile and linoleum floors are colder than carpeted ones because the carpeting provides extra insulation on the floors.
Combined with thermal bridging through the floor joists which are almost directly exposed to the cold outside temperatures it will make the floor surface feel cooler than the surrounding floor.
Some floor materials are naturally colder than others.
How to reconfigure a window air conditioner to get colder than 61 deg.
Tile will be colder than wood or carpet every time.
How to keep a second floor warmer.
More radical folks change the flooring.
A quick and inexpensive way to make a window refrigerated air conditioner make a room colder.