The answer here is the obvious one: You need to insulate and install storm windows. Do that before you consider any equipment - otherwise it will all be sized incorrectly. There are ways to insulate the house. Cellulose can be blown in from the inside or the outside. Closed Cell Foam can also be injected the same way. Cellulose can be blown into the attic and the crawl space walls/rim joists can be sprayed with foam also.

Sorry for the late reply, been away. The room is built above the garage. There is a small attic with blown cellulose insulation. I'm sure the walls are insulated. The small knee wall attic through which the ducts are routed (three supply registers) could probably use some batt insulation on the floor, although I believe this attic might be above a room downstairs. The ducts are not blocked, there just isn't as much air flow in to the room. I'm going to call an insulation company who did the ceiling attic of this room years ago.

So I have 2 Infinity units on 1st and 2nd floor with dual fuel on 1st floor. I am finishing the basement and going to add zoning to the 1st floor unit for the basement. The upstairs is already a zoning system with 2 zones. With the colder weather, it would be nice to have gas heat upstairs. Could I have the upstairs as a zone on the 1st floor unit when it calls for aux heat? Ie can the relay that asks for aux to come on, just call for a zone? Ideally it would be for first stage of aux and then if needed, the strips could come on as second stage. The ducting is not difficult because of a garage. I can always just make the upstairs a zone for the winter and see how I like it, programmed to call for heat 1st with a higher set temp than the upstairs unit. Not as elegant. Extra stat on the wall to program. Don't know if there would be pressure issues if both units were running. The furnace is a 60k unit and I used to setback the downstairs at night so that it barely runs. I have since upped it at night to help heat the upstairs which is not ideal. I think in the morning, as it gets to temp, it might have a hard time keeping the upstairs warm also. But really, it runs for 15 minutes on high stage to warm the downstairs 3 degrees so I doubt it would be a problem. In NC, tight house. 60k on the furnace is on the high side for the downstairs.

I have a walk-up attic (900 sqft) that I finished off a few years ago. Half the space is for the TV, the other half a game room for the kids...ping pong, fosball, etc. I'm in CT, it was a typical attic space, open framing with FG batt insulation...hot in the summer (110-120 degrees), cold in the winter (50-55 degrees). When I finished it off, I used sheets of 2" thick polyisocyanurate foil-faced foam insulation on the ceiling rafters, and 1" polyiso board on the gable end walls. I installed furring strips 16" on center over the foam insulation, then drywall was screwed to the furring strips. I have radiant floor heat in the rest of the house and was going to add two loops to the system to warm the attic. The two additional loops were planned for in the oiriginal plans when I designed the house. Ended up not having to install the loops. Winter temps the attic gets to a low of about 66-68 degrees. As soon as anyone goes up there or turns on the lights, the room warms up a few degrees. During kid parties or sleepovers, they open the windows to cool the attic down, even in winter. The polyiso is a great radiant barrier, stopping heat gain in the summer. High summer temp up there is about 77 degrees. Since the air handler for the second floor of the house is behind the attic kneewall, I did add a few supply and return outlets to move air and to keep the attic from getting stuffy in the summertime. At R-7 per inch, polyiso is quite effective. Better than that, it stops air infiltration and eliminates drafts, resulting in an even more effective R-value than when compaed to fiberglass. It also is an effective radiant barrier. Cellulose would be my second choice for insulating an attic. Best, Mongo