WinterSnowfall: With classic single-pane windows, you'd freeze to death over winter in these parts.
Jinxtah: This building is from like the eh.. I'm guessing 60s or there abouts. I'm not sure how many panes of glass the windows have, but it's old, and I can feel the cold just seeping right through, which is always a problem when it's cold. Thank god for radiators though, but still, my apartment takes ages to heat up, and it costs way more because it doesn't retain the heat, and a lot just escapes those same windows, since they're RIGHT under them, you know?
It may seem odd, but placing the heat source under windows is by design in general construction for a few reasons. As the heat rises, it mixes with cooler/colder air creating a more uniform temperature in the living area. It also helps to create a "heat curtain" to keep cooler air out while operating. If you think about it....and the heat source were located on an opposite interior wall from the window; as the heat came on, and started to rise, it would actually pull in more cold air, as it followed the the flow down, and along the floor to replace the rising air at the radiator. This would also help to create drafts, and very uneven/worse temperature gradients in the living area.
I was made aware of this by by one of the plumbing/heating contractors many years ago on one of my jobs. That said, one of the best upgrades to a living space suffering energy loses is a window and door upgrade, which unfortunately probably won't apply in your case? Heavy curtains, or plastic taped over the opening is probably about the only other temporary solution for now :/