Doors and Windows - Standard Storm Windows

I have a huge sunroom with 11 standard storm windows. they are over six feet tall and the only type of window in the sunroom. My problem is, the window glass are very heavy and to open them you have to push in tiny little slide bars and hold them in while you are trying to lift up at the same time. The windows are very heavy and I can not push and lift at the same time. Therefore my windows are always closed and it is so hot in the room that you can't stand it in the summer. Is there any kind of a handle that can be put on these windows that I could grip well enough while I'm trying to lift? Please, if you have any ideas; let me know.
Thank you