I have been told (including in comments by awesome user Unslander Monica) that a foil sheet placed on the interior side of an air-sealed window can help prevent radiative heat loss through that window. I have a few questions about this:
- Does it matter what kind of foil I use? Is anything better than the "normal" foil used for food storage?
- Does it matter whether the cavity between the foil and the window is not completely sealed? (I already have plastic film that should be blocking outside air from getting in through the window)
- Does foil work significantly better than any white opaque surface?
- Are there common conditions that I might not think of where this would not work?
- Can foil also prevent radiative heat loss if I use it to cover a wall/ceiling? If so, is is partially effective if the wall/ceiling is only partially covered?
- If the answer to #5 is "yes," then I am guessing that I will need to make sure that any pipes running through the covered walls do not require heat from my living space to prevent freezing. Right?
- If the answer to #5 is "yes," are there any special precautions I should take in a room heated by baseboard heat?
- Can I also use foil on my walls/ceiling to increase solar heat gain when condition are appropriate? If so, is there something better I could use?
- Catch-all question: Is this a giant waste of time? I don't intend to work on this until I have upgraded/insulated windows/doors/attic, sealed small cracks, and improved my personal habits. But I am renting so I have limited ability/desire to tear open walls or buy major appliances.