So is Double Glazing a skill to which you might turn your hand? A double glazed window is nothing more than two layers of glass separated by space. The air between the two layers offers the insulation and a certain amount of sound filtering. A thin layer of metal oxide is spread on the outside face of the interior section of glass. This lets the sun pass through it, but stops the heat from getting out.
Sometimes the air between the glass is replaced with gasses such as Argon or krypton which are denser than air and help preserve heat. These are supplied by Double Glazing experts at a higher cost to the normal air-filled ones. Air-filled windows have the advantage that an enthusiastic DIY-er can replace the glass and any “desiccant” or “drying agent” without the aid of specialist tools. (Don’t use putty because it dries the seal and makes it crack.) Finally, windows must also be fitted with a good hinge to give an effective final seal, when closed.
It’s worth a try if you really enjoy your DIY. You can use white oak or even pine. The frame should be formed to accommodate 1/8″ glass and 3/8″ trim. The glass sheets are readily available from a home-supply store and the seals can be easily replaced should moisture eventually seep in. You’ll certainly know you’ve not done your best work if the windows begin misting up, between layers. It’ll be back to the Drawing board!