Thermal images of the doors

It is easy to get a little carried away when shooting with an infrared camera, and I did that shooting over 300 images in a couple of hours.  To try to make sense of them, I'll focus on a few areas at a time, each in their own posts.  The first area will be the doors as seen from the inside of the house.

There are three doors to my house, front, back, and side door to the garage.  To get consistency in the images, the IR camera scale was locked to a range of 60 to 71°F.
  The two pictures below are for the back door.  It is a raised panel wood door with single pane glass with a storm door just outside of it. It is immediately clear that the door is a much worse insulator than wall surrounding it.  Also, the raised panels (which are thinner than the rest of the door) are almost as bad as the glass when it comes to insulation.

The front door, show below, has the same problem.  The raised panels are very poor insulators, but even the heavier door sections are not as good as the walls nearby.  To make matters worse, both the front and back doors seem to be leaking air from the bottom seals.  The front door also has a glass screen door outside of it.

Heat loss depends on both the insulating value and the area (size) as well.  So a small spot on a wall (for example) that is poorly insulated is not as important as a larger area, like these doors.  So replacing the doors really should be a priority.

   But doors are very expensive.  A new front door would costs many thousands of dollars to buy and install.  A new rear door would be slightly less expensive, but still likely to cost thousands of dollars.  So replacing the two doors could exceed $6,000.  In contrast, the complete house was air-sealed and had blown-in cellulose insulation installed for $5,000 a few years ago.

   The additional problem with replacing the doors is that while they will likely be improved, they might still only be an R3 or R4 equivalent in insulation which is still far less than the R13 that is typical for 2×4 walls.  So a lot of money would be spent and the IR images might still look bad.

   One alternative is to get a new storm door with double pane insulated glass.  That would probably cost $400 and be relatively easy to install.

    An additional, and ambitious plan would be to build my own highly insulated door of my own design.  I'd love to use more than the standard 2" of thickness typically allocated to a door and expand it to the 4" space that is available, but getting a door knob that wouldn't hit the storm door would be a challenge.

   A last alternative is some sort of highly insulating inside panel to improve the door. Insulating Art anyone.?

The door to the garage, above, looks better than the other doors, but that is only because it is right now opening into a semi-heated (50°F) space.  The door is no better than the other doors, it just isn't being challenged.

  One quick test was done on the three doors using a single point IR thermometer (Radioshack 22-325).  The measurements were made on the middle of the raised panels for the front and back doors and on the glass for the side door.

63°F Front door

62°F Back door

65°F Side door

By way of contrast, the front door has a sidelite that I insulated with 2" of rigid foam (see separate post).  The raised panel on the sidelite measured 70°F or basically room temperature.  This was a huge improvement.