Log homes and energy efficiency

On a recent road trip around the State of Washington, we stayed at a motel constructed of older style Pan Abode buildings built sometime in the late 50’s. 

The structures seemed in remarkably good condition for their age, but the stresses on these structures are perhaps not what they would be in a wetter area of the state–like west of the mountains–in the Seattle area.  The structures seemed well suited to their hot and dry climate.

What I found interesting was the insulating ability of the 4″ thick walls–or their lack of ability would perhaps be more accurate.

This first picture is of the exterior wall.  The red rectangle corresponds to an area at the interior that will be discussed below.

Pan-abode type building

This next picture is what the wall structure looks like.  You can see the double tongue and group shape with the wall being approximately 4″ thick.

Pan-abode type wall structure

On the interior, with thermal camera, the wall and pillow temperatures show in the next two pictures.

Thermal image Thermal image

In this next picture we see the wall with the pillows moved away from the wall to reveal how the wall was “insulated” by the pillows.  The wall, heated up by the direct sun shining on it at the exterior, could not give up its heat to the interior as readily as the other areas of the wall. Thermal imageThermal image

My understanding is that modern Pan Abode structures are a double-wall type of construction that allows for the installation of insulation inside the walls.  This would certainly be required by modern energy codes for both heating and cooling. 

Regardless, these pictures demonstrate very well how poor 4″ of wood is as insulation (about R-4).  By themselves, it would take exceptionally large logs to meet modern energy efficiency standards.

By Charles Buell, Real Estate Inspections in Seattle

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What is a little missing insulation between friends?

Sometimes it is the little things that get you.

However, these little things can end up costing you a lot of money over time.

At a recent inspection I had a house where the insulation details were not well thought out.  Without going into a discussion about the “type” of insulation, lets just discuss in the simplest of terms how the system was working—or not working as the case might be. 

The following sketch shows how the walls are insulated up to the ceiling and then the roof plane itself is insulated.  What got missed was the wall between the roof and the ceiling.  This space above the ceiling is essentially “conditioned” space and the short wall between has to be insulated to have continuous insulation around the conditioned space.

This next picture shows what that un-insulated area looks like with thermal imaging from the exterior.  However this is a space between the second floor and the main floor ceiling.

Going back to the original drawing, here is an exterior view of that un-insulated space—as seen by thermal imaging.  The un-insulated areas appear warmer (the white-yellow areas)

The same areas of the above picture as seen from the inside of the attic space with the un-insulated areas appearing “cooler” (the black areas).

These areas will need to be well-insulated to prevent wasting of energy that increases both heating and cooling loads of the home. 

The fiberglass insulation should be encapsulated, and for more information about that:  All Fiberglass Insulation Must be Encapsulated.

 By Charles Buell, Real Estate Inspections in Seattle

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Dancing blind!

There are three means of heat transfer that we talk about in the context of heating our homes. While all three are likely to be involved in all heating scenarios, there is usually one that predominates.

1. Heating by radiation

2. Heating by conduction

3. Heating by convection

Everyone is familiar with that feeling one experiences standing in front of a fire or out in the sun on a cold but sunny winter day. The warmth felt on one side of your body is radiational heating.

When that radiant energy strikes a warm surface, that heat is “conducted” to other parts of the material warming the material up internally by conduction—it does the same with your body if you stand in the sun long enough. Of course if it is really cold outside it is helpful to turn around and let radiant heating do its job on the other side–while the other side cools off.

So that leaves Convective Heating–perhaps the “coolest” of all.

What does convective heating look like? Well typically it does not “look” like anything but its effects can be quite visible. It can create winds strong enough to generate electricity or be witnessed as hurricanes. It is the result of heat movement in a fluid and it can either be “forced” (as in a convection oven) or “natural” due to changes in buoyancy–as in warm air rising and cool air sinking.

At an inspection a while back I saw a good example of convection made visible. I call it the “Dance of Convection.”

The dancing blinds are the result of heat rising off the hydronic heating radiator beneath them.

convectioncurtains

Convection plays a huge part in all of our lives from the way we heat our homes, to the way we ventilate our homes and even the weather around our homes.

By Charles Buell, Real Estate Inspections in Seattle

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