Our 10ft.X 11 ft. dining area is an addition, built over a crawl space, with two exterior walls (facing SE and SW) that are mostly window. This room is always cold in winter, and I feel like it is more from cold air than from a cold floor.
The crawl space has some heat supply, and the exterior walls of the crawl space are insulated on the outside with styrofoam.
The ceiling of this dining area and the 6 inch exterior walls (that are not window) are packed with batt insulation. However the windows are 5 feet tall and almost 21 feet linear width (double-paned sealed, 24 years old if that matters). There are 4 heat registers (2 for each ext. wall) and the area is wide open to the rest of the house.
We have had several furnace people out to look at why the space is so cold in winter... they have all agreed that the 4 heat registers should be sufficient, and that the furnace (5 years old) is powerful enough etc. So I believe the problem is either from the expanse of windows or having a crawl space rather than full basement underneath.
We are now planning to replace the flooring material and would like to fix the heating problem first. We would greatly appreciate advice on where to put our money:
1. should we put in radiant electric floor mats (still keeping the 4 heat registers) or would that mean only the floor would be warmer and the temperature while sitting around the table will still be unpleasant?
2. should we instead replace the windows with triple glazing or whatever is the newest window technology?
3. or should we replace the furnace with a high efficiency one that might blow hotter air into the room? (ps it seems that by the time the air gets to the heat registers in this area, it has already cooled off quite a bit even when we close off the heat in rooms closer to the furnace)(and the basement gets almost unbearably hot from heat radiating through the ductwork nearest the furnace, but ducts are practically cold as they get to the farthest rooms...but furnace people say there is no problem with the design)
I suppose all 3 would be the best but we cannot afford to do more than one... and since the floor is being changed, now is the time if radiant heat is the best solution.
Thank you to all for your suggestions.