Double Glazing is expensive and retrofitting even more so. Using basic principles of keeping a layer of air in between 2 layers of glass, I decided to use perspex as the indoor layer and keep that on our windows with magnetic strips. Perpex has good low E properties, is relatively inexpensive, shatterproof and does not break as easily as glass.

Step 1: Materials and Measurements Required

1. Measure your window - glass only. Get the sheets from a glass/ acrylic dealer or wholesaler. Usually they will cut to measure without extra cost.
2. If your window is "fixed", ie does not open, then the extra insulating layer can be bigger than the glass by a margin of about 1cm all round, giving better "seal" and less window frame surface exposed to leak heat and attract condensation
3. If your window has latches - the extra insulating layer has to be exactly the same size as the glass - which means you will lose 1 cm of see through window round the perimeter once the magnetic strips go on.
3. Materials required:
- perspex (acrylic) 2-3mm thick, optical / window quality - do not remove paper backing till ready to mount on window
- self adhesive magnetic strips 1cm wide - measure / calculate the perimeter of the windows to get an estimate of how much to buy
- craft scissors

Step 2: Attaching Magnetic Strips

1. Peel off the backing of the magnetic strip and attach it carefully aligning the edges so that all 4 edges have a full length strip
2. cut off a similar length of strip and place it on the strip that is already attached to the acrylic. This is to ensure that the 2 strips are aligned with respect to their magnetic fields so that they are attracted to each other rather than being repelled.
3. do not remove the backing of adhesive strip until ready to mount onto window / window frame

Step 3: Mounting Acrylic to Window Frame

1. you will need another pair of hands for this
2. trail fit the acrylic onto the window frame, noting where the edges will be. Mark if necessary with pen.
3. Hold in position whilst assitant slowly peels off backing for the second adhesive strip (this is the one that "belongs" to the strip that will stick onto the window frame, but is now nicely positioned on the strip that is stuck to the acrylic
4. as the paper backing is peeled off, press the acrylic plus magnetic strips (x2) onto window frame
5. repeat so that all 4 sides are stuck down.
6. picture shows acrylic mounted onto frame, with paper backing still on

Step 4: Voila! DIY Acrylic Double Glazing

1. peel off the paper and you will have a nice piece of acrylic stuck to your window frame. The air trapped inside will help insulate the room
2. Views through are not affected if you use good quality acrylic
3. If the piece of acrylic is not large enough to cover all of the frame, you will still have some condensation on the exposed bits of aluminium or wood frame.
4. If your magnetic strips have gaps in between them, it will reduce the insulating qualities of this design.
5. close up shows magnetic strips