I’ve often found myself speaking to a Homeowner or Builder about the term “Thermal Barrier” . This week I ran into the perfect example to explain. It quite simple in one respect and not so in another. It’s that the insulation is the thermal barrier. But when its not aligned it’s a big issue. So imagine this, you are lying in bed and getting too hot. The blanket is your thermal barrier. But if you stick out a foot or leg as we do to cool off, that is a thermal bypass. That works to help us thermoregulate, but in houses? It would be like opening the window to cool the house while leaving the furnace run full bore. Doesn’t make much sense does it? So how does this relate to the insulation in the walls and attic?
Picture this now, in an average house you have insulation in the attic and walls and in new home insulation in the basement as well. And it’s the basement that I’m looking at here in this example. You can either put insulation on your walls, all the walls or in the ceiling. This makes the continuous thermal barrier, which is key here. But what if for one instance we have insulation on some of the walls and some of the ceiling? This is not continuous and is a thermal bypass. The cool air radiates in through the uninsulated walls into the partially insulated basement and makes the uninsulated space/floor cold.
Here is the picture that I’m thinking of. This builder did just that. Parts of each component are insulated but not all of either. That is the issue. Remember the example of the leg sticking out of the bed, the uninsulated wall is an issue unless you were to insulate all of the ceiling. You want to be sure that you have continuous thermal barrier alignment for this to work!
So remember the thermal barrier in a house is a thick warm blanket that wraps the house. Something left open is a bypass and lets out the heat. By the way this is just as true in cooling seasons too.