Double-paned insulated glass consists of two layers of glass that are sealed together around the edges with an inert gas injected in the insulating gap between them. Over time, the differences in expansion and contraction — from the effects of heat, sun, and cold — between the two panes can cause the seal to fail. This allows the gas to slowly leak out and be replaced by moisture-laden outside air, which can give the window a hazy appearance between the panes. Check the warranty that came with your windows to see if the glass is still covered. If it isn’t, you will either need to replace the glass or window unit. Home Services Direct would be happy to replace your bad seal. We would remove the sash and board up the window to prevent animals and weather from coming in. We would use the existing sash and install a new double pane, argon gas filled window. It’s approx. one day labor to take the sash out, board up, and reinstall the sash. Lead time on the glass is about three days