Can you post a photo of the foundation/framing/underside of this? what handymac said is likely the case. You've got lots of ways for air to flow in through cracks and get inside the room, because it wasn't initially built as an indoor space.

Plywood as the floor right now under the carpet scraps

Underneath the porch.

Ideas? Can a new floor be put down somehow?

More important than insulation in the floor, is insulation in the ceiling. Are you planning on doing that?

And are the windows/doors in there double-pane? Because if it was just meant as a wind break, then the previous owners probably would have just put some cheap glass in there instead of something insulating.

greg_2015, It is currently not insulated in the ceiling. We plan on insulating and making it a vaulted. As far as the windows go, I am pretty sure they will be replaced. We plan on moving the patio door to the north side(back yard), and closing that section in to put in a fireplace which should help as well. LOTS of work to be done, but want to make sure we are doing it correctly the first go around. ;)

Ahhh ... so you are planning on doing an extensive gutting and renovation. I thought you were just going to slap some insulation down and hope for the best. :)

If you can't physically get under the porch to insulate, I wonder if you could pull up the plywood flooring and add insulation from that direction before putting the flooring back down.

Just a thought, I'm no expert.

greg_2015... Yea, it definitely needs some improvements which nothing too difficult but obviously has to be done with some thought. ;) The room is in the NW corner of the house... so it gets a lot of the wind/cold from through the winter months. Lifting the plywood would actually be a great option I think... unless we teach the kids how to insulate... they might fit. ;)

Here's a video that shows how you could add the insulation from the top if you ripped up the plywood.

Even if it's insulated to the max and has the very best windows, it still need a source of heat. That much glass area is always going to mean a high heat loss value in the calc.

Here is an online room heat loss calculator, which will tell you how many BTUs the room would need. http://www.dimplex.com/en/customer_support/heat_loss_calculator

Casey

Has this project ever been completed by now? We are in the process of building a 4-season porch from the original open porch that came with our 1917 home in NE Ohio.

Sometime in the 1940s, the previous owners had crudely enclosed this second floor porch with nine simple casement windows that open inward, but there is no insulation, nor any HVAC in the enclosed porch. The porch faces NW where most of the bad weather comes from.

The porch is on the second floor, over the back hall and the pantry area of the kitchen.

We had the original porch demolished, down to the floor joists, including its original almost flat roof and knee walls. So far, we have new 2x6 stud walls up, new subfloor, and five new Marvin Ultimate Casement windows installed, along with a new 4:12 hip roof. Once the rough electrical goes in (Monday or Tuesday) the room will be insulated in the walls and wherever we can stuff it into nooks and crannies, and in the ceiling, leaving space in the roof for air to go from the soffit vents up to the ridge vent in the roof.

We're not sure whether to install sheathing on the ceiling joists before adding the porch ceiling strips or just nail the ceiling strips right to the joists after the insulation is installed. Which is best/proper/correct? We're trying to eliminate air infiltration. Sheathing will be going onto the walls after they are insulated, and then, vertically oriented V-groove boards are being put on top of that.

Heating will be provided by a 6' Runtal electric baseboard heater (the room will be about 8 1/2' x 9 1/2' with an almost 8' ceiling). No AC, other than the residual from the adjacent bedroom when the inside porch door is open.