Well-built and properly installed windows will not have debris, stains or condensation between the two panes. When you see this it indicates that the seal of the window is broken. If this is the case you will not only have dirty windows, but will be losing money on the heating or cooling bill. A DIY solution for cleaning the windows is not difficult but will not solve the energy loss problems with your thermal windows.
Attach a 1/8 inch metal bit to drill two tiny holes in the window frame very close to the inside pane. Keep a cup of cool water at hand and dip the bit whenever it heats up. Drill the two holes on the inside of the window frame opposite each other, one at the bottom of the frame and one at the top.
Cut two lengths of plastic tubing small enough to fit through the holes you drilled. Insert one of the tubes through the hole in the top of the frame. Place the other in the hole at the bottom. Use enough tubing to extend to the middle of both panes in the area beneath the two panes.
Insert a small funnel into the top tube. Pour window cleaner into the tube while holding the tube and aiming the flow at the dirty windows. Continue this process until the windows are clean. As the water flow has only gravity as the force behind it, it may take a lot of solution to dissolve the dirt.
Extend the tube on the bottom of the frame into a plastic gallon milk jug that is placed below the window frame. Siphon the dirty liquid out of the space between the two window panes in to the jug. Discard. Remove the tubing. Let the window dry. Cover the holes with clear packing tape.