How to Determine The Best Window for Arizona’s Climate?

Understanding window terminology and ratings can help you in your search for replacement windows for your Arizona home!

By having energy efficient windows correctly installed into your home, you can greatly impact your energy costs. This is due to the fact that an average Arizona home loses up to 30% of it’s cooling cost through air leakage and unwanted solar heat gain through inefficient, aluminum, single pane or even dual pane windows.


This makes upgrading your old aluminum windows to new vinyl thermal pane windows, a great investment! While shopping for new windows, it is important to understand window terminology which explains the overall performance of a window or door, such as u-factor, solar heat gain coefficient and air infiltration.

The energy star rating system is a good place to begin, however, it is painted with such a broad brush that it is not specific enough for Arizona and our unique climate. Energy star recommends a u-factor of .4 or lower for the Phoenix and Tucson valleys, The u-factor measures how well a window insulates. In other words, it is the rate of heat LOSS through the window.

This is not a relevant measure for the Phoenix area, however the u-factor should still be looked at as an overall gauge to the build quality of the window and not for energy savings. Affordable windows recommends a window with a u-factor to be below .3, the lower the number the better or more solid the window will be built. This will ensure that your new windows will last a lifetime.


On the other hand, the solar heat gain coefficient (SHGC) is the most relevant window rating for Phoenix area homeowners in regards to energy savings. What is Solar Heat Gain Coefficient? The SHGC is the fraction of heat GAIN through a window both directly transmitted and also absorbed through the window. The SHGC is a measurement from 0 to 1.

The simplest way of reading this measurement is the lower the number, the less heat enters through a window. Think about it this way, a solid block wall has a rating close to 0 while an open hole in your home has a rating of close to 1. For any window to be considered an Energy Star window, in the Phoenix and Tucson areas, it needs to have a SHGC of .25 or lower.

Here at Affordable windows, we have windows with a SHGC of .11 which is greater than 40% more energy efficient than the recommendations of Energy Star. The last measurement to examine when you’re window shopping is the overall air infiltration number. Air infiltration is the air leakage through your windows.

Most manufacturers of vinyl windows, as well as aluminum, fiberglass and wood windows, don’t publish these ratings on the NFRC sticker. They simply state whether it’s above or below .3 cfm/ft2. To be considered an Energy Star window, the air infiltration needs to be below .3 cfm/ft2.

Due to our monsoon weather patterns, we believe you should only consider windows for the Phoenix and Tucson areas with ratings below .1 cfm/ft2, the lower the number the more airtite the window. All offerings by us are .07 and lower depending on the window configuration.

Ready for more information on windows for Arizona?
Call Affordable Windows Plus Exteriors and we will be happy to provide you with a free window consultation where our experts can answer all your window and door questions! By Jeff Caruso Affordable Windows

By Jeff Caruso
Affordable Windows

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