Wanted to get the opinion of an expert.
Attached is a photo of a customer's window.... as you can see there is a large cold spot above the window... Here's my opinion..am I right?
The large horizontal cold spot is thermal bridging from the double 2x6 or 8 top plate.
John, Thanks for the review in Home Energy 101. Sometimes, as auditors, we get so enamored with the technology, we forget the basics. Comments like this, keep my feet firmly on the ground, and improved my audit results.
This is not thermal bridging and it has nothing to do with the blower door. This is the ceiling plane meeting the wall plane, and this is thin insulation at this area combined with possibley a slight breeze blowing or convection causing cold air to ride up under the first couple of inches of attic insulation. The very dark spot every 2 feet corresponds to the roof trusses/rafters and the week insulation adjacent to them. In the mid-Atlantic we are required to install hurricane clips - metal clips that hold the trusses/rafter down to the top plates. We see the conducted cold from the metal as a dark spot every 2 feet even if it is not connected between with a dark area. The blower door would have caused the cold air to come down the wall/ceiling joint into the wall - but this is not the case, and thermal bridging would have made all the studs show as much as the top plates.
Slight Breeze? He said the bower door was running.
As I said:
"The blower door would have caused the cold air to come down the wall/ceiling joint into the wall - but this is not the case, and thermal bridging would have made all the studs show as much as the top plates."
There is no connection of this area to the blower door through the attic. The only possible connection is from the bottom of the wall at the baseboard or through receptacles, etc in the wall, then up through the wall to the open wall/ceiling joint where the cold areas are. If this were happening, the cold would extend down as "icy fingers" into the wall below, but it is not.