It would be wonderful if questions such as this could be answered with information you have furnished. Ask your utility company for an analysis or pay a professional for advise.

Thank you, but I'm confused. Is there something about the question that is inappropriate or it's too complicated or ???

Creekgirl,

The room is a sunroom... which is essentially an outdoor room that is unconditioned.

In the day these were popular people would only use them when the weather was mild, or a wee bit chilly... hence the term sunroom?

Sit out there of a morning as the sun come up drinking coffee or at night as the sun goes down drinking hot cocoa. (sun rooms also imply hot when the sun is out in force.)

In some cases the sun room merely only has screens to keep the bugs at bay. But even in this instance they were still called sun rooms.

If your plans entail only periodic use of the room you could fit a window unit within the frame of one of the windows. Because you haven't shown pictures this may be more complicated than what I am imagining in my head.

Without being insulated the window unit will probably run and run, and may not be no where near what you consider comfortable as the temp goes up or down outside. (There are window units that make heat as well as cool, those are the ones to select for this application. If you're looking for the cheaper fix nothing is cheaper than window unit application. When they break you go out and buy another one. Controls are often not as good as traditional AC / Heat especially in a room (sun room) that was not originally "designed" for the use of what you want.

If your thought is to simply run duct work from your existing AC / Furnace this will probably throw your whole HVAC system into a tail spin. Doing these kinds of things aren't really a good idea. (unless you live in a mild place that rarely see's a day over 90F in the summer and not less than about maybe 45-50F during the winter.)

Longer term solution: rehab this room, insulate it top to bottom, remove the 3 inch windows all the way around incorporate traditional sized windows then replace your HVAC system to the home and include the sun room within the calculation to size the unit appropriately and then remove sun room from the vocabulary description of this house. (call it a bonus room)

If the sun room is over some sort of crawl space there is work to be done there too. If this room is on a concrete slab not so much.

Thank you. I've added a photo!

The sunroom has electricity, but it is not connected to the home HVAC. I'm getting the feeling that given a glass roof, AC/heat units and/or heat pumps would not be adequate to deal with the temperature extremes. I'd have to cover the glass roof somehow as well. But I'm having trouble finding good solutions online. Films get cloudy or loose over time, tints wouldn't insulate, a mechanized roll out shade system would be overly expensive, etc. I wish there was some way to re-roof it in wood, or add a covering to the glass roof!

Riffing here, since you need an inexpensive option — garden centers sell shade screening that you might be able to put over the roof during the warmer months. A wood burning stove might help keep it warm in the colder months, if there’s a place to install a flu. Good luck, I hope you find a way to make nice use of the space.

There's no reason a properly-sized heat pump can't condition your Sunroom. To control radiant heat gain, I suggest you consider roller shades https://www.thermaldesignsinc.com/

Putting a silver saddle on a jackass is a brilliant idea compared to what you purpose. That is a wonderful room plant lovers would die for but it might be no more than wasted space for your lifestyle. It would be a toss up between building a new room and making this one into something other than which it is designed for.

I'm getting the feeling that given a glass roof, AC/heat units and/or heat pumps would not be adequate to deal with the temperature extremes. I'd have to cover the glass roof somehow as well.

Yeah now that I better see it, I think it would be difficult to cool this area properly as it really is not designed to be used like how you want to use it.

Not saying you couldn't do it, but is it really worth it to try? I don't think so given the heat gain from the glass roof and because of this it probably sits in the sun all day long.

I see design related problems all the time and sure you could throw money at those problems and the solution isn't like redesigning, it's just feeble attempts of throwing money at it and usually only making it worse. (because it doesn't work & you spent money + time trying.)

That looks like a vintage Four Seasons sunroom and they do make shades specifically for that style of sunroom.

https://www.thermaldesignsinc.com/four-seasons-sunroom-shades/

Add shades and a mini-split as suggested in previous posts, and you should end up with a much more accessible space.

Note the shades in Four Seasons HQ.

Sunrooms are fairly common, and while heating and cooling them can be a challenge, it's done all the time. You have the option to adapt the unconditioned Sunroom to make it more useable or you can tear it down and start over. Let's "ballpark" the cost of the latter option. It looks like the structure is around 12' x 20' so it's around 240 SF of living space. If we assume $250/SF to ballpark the estimated cost of the addition, you're looking at a $60K bill plus the cost of demolition and disposal. I think you'll find the cost to retrofit the space with roller shades and a mini-split heat pump will be a fraction of that.