Aluminium is an extremely poor insulating material. One-third of the heat transferred through an aluminium-framed window is conducted through the frame itself (unless the frame is a specialized composite insulated frame).
We recommend a simple solution for the home handyperson.
Attach a movable supplementary frame
For each window opening, you can fabricate a pair of identical frames (similar to empty picture frames) that will perch side-by-side against your existing aluminium window system. You can then attach the tape and membrane to these fabricated frames and you will achieve a sealed air gap between your ClearComfort-faced ‘picture frames’ and the existing window. To open the window, simply remove the first ‘picture frame’ and stack it in front of the second ‘picture frame’, allowing access to the sliding aluminium manufactured window, until you want to close and seal up your window again.
Frames made of timber will provide the insulation lacking in your aluminium window and will provide the same insulation benefit as a standard double-glazed timber or composite-framed window.
Choose a size of timber appropriate to the size of your largest windows. We suggest a minimum size of 40 x 20 mm for “average” windows, larger for full-height or floor-to-ceiling windows.
Each frame is lightweight and easily made from off-the-shelf components available at hardware stores. The frame above was made using plain 40x20mm softwood, which can be painted or left natural.
Aluminium flyscreen framing can also be used for smaller windows. If using such framing, sit the new frames forward of your built-in aluminium window frames so that the two aluminium frames are not in contact, and your insulation benefits are maximized.
There are added benefits to using these frames:
· you will block drafts that blow through ill fitting windows, and
· will be insulating the highly heat conductive aluminium frame around the glass.