Casement Windows, Double Hung, R-Value, & U-Factor

As we mentioned in last week’s post about single, double, and triple pane windows, we’re going to spend the next few weeks focusing on explaining the jargon around windows.  By knowing how to talk about windows, you’ll better understand not only how to communicate with your Texas custom home builder, but also what you want for your dream home.  Your window choice does not just affect the ascetics of your home, but also the functionality.

Casement Windows

A casement window is a window that has one or more hinges which attach the window to the window frame.  These can be a single pane or a pair of panes within a single frame.  There are a few particular names that can be used depending on where the hinges are located: hopper windows are windows that are hinged at the bottom, while awning windows are ones that are hinged at the top.

Single & Double Hung Windows

The major difference between double and single hung windows is that for single hung windows, the top sash is fixed and will not move, while both of the sashes on double hung windows will move up and down and may also tilt in.  Because of this, many people choose single hung windows for the lower story and double hung windows for upper levels as they are easier to clean from the inside.

UV ratings or the U-Factor

UV ratings or U-factor is the measurement of how well something performs when preventing heat from escaping a structure.  The higher the U-factor, the worse a product is performing, the lower it is, the better it is performing.  The typical window U-factor will fall between 0.15 and 1.20.


When talking about insulation, the R-Value is often the most discussed.  The R-Value simply measures the resistance to heat flow, therefore, a higher R-Value means a greater reduction in energy consumption.

Difference between R-value and U-factor

The difference between R-value and U-factor is that while the R-value is to measure heat loss resistance, the U-factor is used to measure the heat transference rate (heat loss).