I'd be careful not to cook your beardie. You would get the 'greenhouse effect'.
Is it a glass viv?
Not too long ago I came across a video on You-Tube that showed a kid really upset about his beardie. Apparantly, he left his space heater in his room (fairly close to the viv) and came back to a very unfortunate scene.
The temperatures exceeded what they should be and the poor thing cooked to death.
If you get direct sunlight coming through the window, I wouldn't advise it. If it is northern light, then it shouldn't harm it, but I would monitor the viv for a while to confirm that the temps aren't exceeding 105-110 F.