Well I get this question so often. I think if you want a four season room then just build an addition and get it over with. I live in the Northeast and I love my porch, but I really can't use it in the winter. But thru the Spring, Summer and Fall its' just great. Thats where I read my Sunday paper! Where I fall asleep or hang around with my kids. In late fall, when it really starts getting cold, we close it up for the winter. The three seasons we get out of it each year is something we look forwar to opening is the Spring. Can't you give up that one season! In my opinion a four season room is just another room added to the home. But the screen porch, oh - the breeze. Here is a link that might be useful: My Album

Lower the ceiling to eight feet and get 6 foot windows.

Post a picture Have some fun in your room.

We already have a zone heating system with 3 zones - the one that heats this room also heats the kitchen, mudroom and small laundry room. Honestly that zone doesn't turn on much as Zone 2 controls our living room, sitting room which is open to the kitchen/dining area. So turning that Zone up tends to heat the entire upstairs (minus this 'porch' as we keep the vents closed in there since heating wasn't helping much). We did have 2 HVAC companies come look at it. We were told it has correct insulation in the floors. In the walls we were told that there would have had to have been a minimum insulation required when the house was built in 2000 in order for this to be listed as a '4 season room' so were told adding more insulation would likely not help our issue. We had the whole house remodeled last year (minus this one room) so we know there is insulation above in the 'attic' area). The last HVAC person suggested enclosing the lower area and adding in floor heating as he said he's seen many of these types of rooms before and they are just too hard to heat with the house HVAC system as you said.