A thermal break is a building element that limits the flow of heat between materials. Think about your morning cup of coffee. If the paper cup is too hot, you put a sleeve on it so you don’t burn your hand. That sleeve is a thermal break. However, the base of the cup and the open top are still allowing heat to escape.
Of course, if you’re being sustainable, you use an insulated travel mug that has a thermal break all around it. When the lid is off, heat flows out, but when you put the lid on, you have just maximized the thermal breaks on your coffee cup.
You have to do the same thing when building a green home – maximize the thermal breaks. This means ensuring that there are thermal breaks around the entire exterior, including under the slab so heat can’t escape into the ground.
There are many types of thermal breaks employed throughout a green home. Every single wood stud or rafter that makes contact with the inside drywall and the outside sheathing of the home is a potential location for transfer of cold air and needs an additional continuous blanket of insulation outside of it (or in between members) to ensure substantial heat loss doesn’t occur. Triple-pane windows use the inert gas between the panes as a thermal break. Energy efficient windows and doors are constructed from less conductive materials on the inside and outside to ensure that heat does not flow through the frames. Areas without thermal breaks are weak spots that counteract all of the other measures you have taken to minimize heat transfer.
It might not be the most glamorous part of the project, but it is critical to consider this important concept when building a new green home.