Any solutions for a really hot room year-round?
Spock (rhp)
start by adding heat reflective film to the inside of the glass. This should be in stock at your home improvement store and is an easy DIY couple of hours project -- just use plenty of the liquid before you squeegee the film into place. you want the highest heat resistance you can find. The point of this film is to reduce the amount of heat that makes it through the glass. *** After that, your strategy should be to prevent the sunlight from even getting to the window. The costly way to do this is an awning. The cheaper way is to cover the window with translucent fabric on the outside for the summer season -- sure, storms will destroy it eventually and if you get a year's use out of it -- that's probably money well spent. What I'm doing at my house is adding a trellis up above the window height. It's mounted on steel poles [two inch water pipe] and is six inches from the wall [so termites can't use it as a highway to the house]. The trellis is two feet wide [projecting outward horizontally from the house] and made of weather resistant 1x3 mounted on edge [i made an upside down "rake" for each end to hold the 1x3]. This is oriented due south -- most of the day, the sun strikes it at an angle and thus can't get directly to the window. {1x3 is made of 1x6 treated fence pickets that I ripped with a power saw.} Think I'm going to grow grapes at the ends to go up and onto the trellis -- cute little flowers, fruit, and plenty of leaves for added shade. [Note: trellis poles should be outboard of the window edges and the whole horizontal part above the window height -- this to preserve ability of the window to serve as emergency fire exit. Ten foot water pipe and two feet in ground works fine for me.]
yimi
a air conditioner split system reverse cycle
lili
Get an a/c?
Mr. P
Reflective window tint foil on the inside, and even fit a black flyscreen to the outside which will give some shading. See about installing a fan in the vent, or if you can - go through the roof to add another vent. You can vent into an attic space with a large fan but is better to duct it out at the eaves. This should be passive so will vent naturally without a fan, or you could install an inline fan in the ducting. Also fit metal blinds as they will block the rest of the light through the window, but your best bet is another vent at roof level.
fucky
You could turn your house into a massive snow globe
Aussie Devil
a air conditioner split system reverse cycle
Richard D
Get an a/c?
Steven S
Slap a window a/c unit into that “giant” window.
Ethelred
White panels, whatever you think will stand up over time, on the outside of the windows. The glass is letting light through and you need to stop it. Trees can help but that won't help till they grow. Drapes or black out curtains are on the wrong side of the glass, though if they are white on the sunward side that would help a bit but nowhere near as much as white panels outside the glass.
Anonymous
Get an HVAC technician to look at the vent to check if there is air coming out of it. The ducting to the vent might be broken. Ducting is good, put a window AC unit and some heavy curtains.
Lyar
The most obvious answer is an air conditioner. Beyond that, you might try reflective window tinting in addition to the blackout curtain.
STEVEN F
Grampa gave the only answer so far that is even remotely accurate. His suggestions are good.