I recently moved into a home and it already has the painted radiant barrier. Would it be good to add the foil radiant barrier as well since the AC unit seems to run excessively? Or should I do something else?
As a general rule, adding another radiant barrier will not add a significant performance value. However, since I cannot see the application in your house, I cannot be sure this rule applies to your situation. It would seem that there may be some deficiency in the application as a properly installed radiant barrier should allow the air conditioner to cycle at least in the evening and nighttime. Perhaps with a little more information:
- Where is the radiant barrier installed, on the roof rafters or on the floor?
- Are there any gaps or places where there is no radiant barrier covering?
- Are there walls in the attic that are exposed to the afternoon sun that are not covered with a radiant barrier?
- Is there adequate ventilation in the attic?
- Is there mass insulation on the attic floor?
Are there air conditioning ducts in the attic and are they insulated?