Elevation

The use of breather tubes is not normally needed in high altitude applications.  In order to avoid utilizing breather tubes you have two options.  First, tempering the glass on a window will generally protect it from altitude related failure up to and sometimes in excess of 10,000 feet.  

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The second option  is to consult Cardinal Glass' elevation guidelines to determine how high you can go before utilizing tempered glass (maintain energy efficiency) or breather tubes (significantly lower energy efficiency).

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With some research, one can maintain the energy efficiency required to meet today's stringent codes and Energy Star criteria.