Monthly Archives: December 2011

A Cold and Frosty Morning: What might an Energy Auditor Do?

Energy Auditing uses observation and science to determine what is happening in a home related to Energy Usage.  Necessary tools are a good flashlight, a blower door, and some way to record the observations for later analysis.

Optional tools, well – Energy Auditors can be come “Tool Junkies”.  Digital Dual Channel Thermometers, Spot Radiometers, Infrared Cameras, Computers, Software, Digital Cameras, Smart Phones, iPads, you name it, an Energy Auditor could probably find a use for it.  Then along comes a Cold and Frosty Morning and you are driving to your next audit. How do you make the most of your drive?

You could look at the roof of various homes as you drive.  On a couple of recent morning drives, I was doing just that. I stopped and shot a few pictures of different homes.  All of these homes were built between 1960 and 2000.  So here they are with comments. I have cropped the images to show just the roof, in most cases this will allow the home to remain one of many.

I have not audited any of these houses, and have only been inside two of them.


This frosty roof shows no frost along the roof line, directly above the exterior wall.  Note how it turns the corner on the hip of the roof.  I have outlined interesting points.   The vertical bar marks the point of the electric service, note the service line.  The lack of frost directly above this area is telling.


The issue here is that heat is being lost into the wall, and then through the top plate into the attic and then out the roof.  If you look at the area where the electrical service enters from inside the attic, you will find some type of holes in the top plate.  Perhaps a larger hole then necessary to allow the electric wiring.  A little caulk could go along way here.



Again the top plate of the exterior wall shows leakage.  Also in this image, an interior wall shows leakage in the upper roof area.

Heat loss occurs in interior and exterior walls.  Just caulking the outside of your home is not the best bang for you effort in sealing air leakage

This is interesting.  Without knowing the inside plan of the upper floor I am uncertain about the cause.  I would look for an attic access hatch, a furnace located in the attic, or perhaps some type of missing insulation along with a unique floor plan.

This picture shows the heavier frost over the eves of the home and less frost over the entire attic.

I would expect to find little insulation in this home, and what is there would be deteriorated in terms of effectiveness.  I would expect to find insulation moved or non-existent in several places.  I would also not be surprised to record a high leakage result from the blower door test.

Another picture of the top plate in an exterior wall.


This is an infrared image of the home with Frost pattern above.  I took this image at a different time then the exterior picture.  Both images are as is, no Blower Door going to exaggerate the air movement. It was also taken in the summer, so the heat coming in from the top plate leakage matches the heat escaping in the Frost Image.

Preliminary Conclusions:

Are these pictures definitive?  No, like most items on an Energy Audit, you need to look at several things to make a firm determination. Picture two is an interior wall, my knowledge of the homes interior, assists with this determination, even though I haven’t audited the home.

These are not necessarily a single look.  At least three of the homes, I have different pictures of different frost patterns.  What might make the difference?

  • Outside temperature and dew point differences.
  • Inside temperature differences.
  • Weather conditions; calm with little wind VS a steady wind of 20 mph or more during the 6 hours before and during the frost buildup.
  • Exposure:  These images have a western, or northern exposure. There may be differences.

What if I look at my house and do not see a pattern?  Look on another day, preferably several days.  The different conditions, may present different patterns.

Does a pattern like this cost me a lot of money?  Perhaps yes!  Perhaps no!  It depends.  To get more details get your Home Energy Audit. Each home is as unique as each person is.

Images like these only paint a picture.  We cannot determine how good or bad the heat loss is from the picture.  It provides a place to look, or not look.

If you take a picture of your Frost Pattern, upload it and put the link in a comment.  Let’s see what readers come up with.

Here are a few more with minimal comments.


Neat image with the Geese flying over.

This is a  most interesting pattern.  I have no idea what is causing this pattern. I would look for high air leakage, patterns on the ceiling with the IR during the Blower Door testing, and it would be interesting to look around the attic in this house.