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Technical specifications

Testing and Performance

There are many factors to consider when choosing a replacement window, including visual appeal, style of operation, affordability, and last but not least is performance. What do I mean by performance? Let me tell you.

Window "Performance" basically speaks to two characteristics:

1. Structural Integrity and 2. Thermal Characteristics.

Let's start with Structural Integrity shall we. Man has always needed shelter, it's one of the 3 basic human needs (depending on who you're talking to I guess). Once we started to realize that our shelter was drab and needed more sunlight, or that we wanted to see the wild animals frolicking outside, windows were invented. There was one problem though...The window didn't protect us from the elements nearly as good as a solid wall did. This is probably because the first "windows" were nothing more than holes cut in the canvas, wood, stone, adobe...well you get the idea. Then, about the first century A.D., the Romans invented the first clear window panes with glass. Even then, with this miraculous new discovery, a strong wind or rain would soak our poor Romans.

Ever since, fenestrators (those who choose to dabble in the science of windows and doors) have been obsessed with creating windows that allowed a transparent, yet sturdy separation between indoors and out. This search has manifested itself in a rating system for windows. The most widely recognized purveyor of this rating system is AAMA, the American Architectural Manufacturers Association.

AAMA writes and oversees testing criteria related to a windows air infiltration, water infiltration, and ability to withstand strong winds and air pressure.

Vista tests all of its windows and patio doors to the standards written by AAMA. The results of these tests provide a basis of comparison with other windows on the market. See our Structural Data page for more info.

Now on to Thermal Performance. Long ago, before there were massive bureaucratic organizations for absolutely everything on earth, windows were made with no true way to compare one versus the other. The only things separating them were price and aesthetics.

Then one day at the dawn of civilization, the mid-60's (thatís a joke baby boomers!), our world became conscious of the energy required to fuel our cars, power our cities, and yes...heat and cool our homes. A window, for all its glory, is still the place in the walls of your home that allows heat to escape during the winter, and heat to penetrate during the summer. A window has never been as good an insulator as a solid wall, whether that wall be made of wood and insulation, or concrete and brick. Well THINGS ARE-A CHANGIN'.

First came the concept of multiple pieces of glass, then came "insulated units", where more than one piece of glass is sealed together with an airtight center (often referred to as thermalpane). Then came invisible coating on the glass surface that stopped even more heat from escaping, then special gases that filled the insulated units that act as an invisible blanket protecting your energy. We are now to the point where windows insulate your home nearly as good as a solid wall!...and we're getting closer every day. So now to the "performance".

This insulating ability that I keep talking about has to be measured some way, somehow. Well some pretty smart folks in deep, dark engineering labs invented a reeaaally long mathematical formula that took temperature data at spots all over a window, and converted it into a rating on the windows ability to resist the flow of energy (in this case HEAT) through the window. This ability to resist heat transfer is now measured as an R-Factor. Higher R Factors mean greater resistance. Greater resistance to letting your heat escape in the winter, greater resistance to letting the hot air in your home during summer, etc... The most widely recognized standard to achieve with regard to Thermal Performance is through the NFRC (National Fenestration Rating Council). NFRC also works with the US Dept. of Energy on behalf of the window industry in the EnergyStar Program.

Vista tests all of its windows and patio doors to the standards written by NFRC. The results of these tests provide a basis of comparison with other windows on the market. See our Thermal Data page for more info.

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