What is a U-Value?


The U-value is an assigned number that states a object’s (or window’s) ability to keep inside a building warm or cool. The U-value states the amount of thermal energy transported through a window. For homeowners residing in a place with a warmer climate like Florida, the U-value is an indicator of how long a home can be kept cold.

Good U-values are an effective way to maintain the amount of energy used to keep a home at an ideal temperature. The larger the U-value, the greater amount of heat will flow through an object such as a window. An efficient window has a low U-value.

Technically, this value is reached through the use of the formula W/( m²K). In this formula, W refers to thermal energy in Watts, and m²K refers to window with the size of 1 square meter [m²] at a temperature difference of 1 Kelvin [K] (=1ºC). Without remaining too technical, a beneficial U-value, to put it simply, should be less than 1.0 W/(m²K). Of course, this number can be obtained through glass and other window energy efficiency options.

For more information regarding FAS Windows & Doors’ products, contact FAS Windows Doors at 1-888-422-1960. If you have any questions you’d like to submit online, you can always ask our FAS expert ! Call us today to schedule your FREE in-home estimate!

Katie Pettit 9/30/2010