Thermal Break Explained

There are many types of windows to consider for your home; double, triple insulated glass, thermal low-E, E+, argon gas, and tinting all have their own unique benefits.  Today, we’ll be talking about thermal barrier or thermal break windows.

With thermal barrier windows, the sash and window frame are insulated against conduction of cold and heat.  This is accomplished by using polyurethane (which is a very poor heat conductor) to attach and also to separate the outside metal parts from the inside.  Home owners in San Antonio know just how important it can be to keep your house cool during the hot months without breaking the bank and thermal barrier windows can help to keep that precious cool air from escaping into the sizzling outdoors.


Because of the close-tolerance aluminum extrusions that are used in the manufacture of thermal barrier windows, this means that they have a significantly higher resistance to heat transfer as well as lower air leakage than do single-paned windows.  When compared to vinyl or wood windows, thermal barrier window performance is equal to or better.  The testing of thermal barrier aluminum windows is very strict with exact industry specifications.  In a 25 MPH wind, for every foot of weather stripped window perimeter, air leakage may not exceed 0.375 cubic feet per minute.  Older non-thermal barrier windows may have leakage of over ten times this rate.  Additionally, thermal break windows are beneficial in that they can reduce the transmission of outside sound by vibration dampening.

Condensation Prevention

Thermal barrier windows cannot prevent condensation; while there is not a condensation-proof window on the market, it is worth noting that a window cannot cause condensation.  A thermal barrier window MAY cut down on condensation by providing a barrier between the heat and cold.  Condensation is caused indoors by your breath, showers, cooking, laundry, and any activity that uses water.  Each one of these activities can raise the humidity in your home.  Condensation is from the humidity in the air responding to different indoor and outdoor temperatures, the easiest way to think about this is to imagine an icy glass of water placed outside in the Texas heat.  Condensation can and does occur on other surfaces, such as walls and ceilings, but it is most noticeable on your window surfaces.  It’s recommended to keep your interior humidity level at about 15-40%.