Some floor materials are naturally colder than others.
Colder on floor or window.
If the second floor of your home stays cold in the winter even when the first floor is toasty it may indicate that your home is improperly insulated or ventilated.
Typical solutions include putting rugs on the floor.
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.
More radical folks change the flooring.
Hardwood tile and linoleum floors are colder than carpeted ones because the carpeting provides extra insulation on the floors.
Concrete clay or other masonry does a great job of holding heat even if it s colder than we d like.
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.
How to keep a second floor warmer.
How to reconfigure a window air conditioner to get colder than 61 deg.