U-Values, what are they all about?

Here at Vermont Modular we have repeatedly talked about R-Values that measure the amount of Resistance insulation provides for the movement of heat.  The greater the Resistance (R-Value) that translates into less Heat Loss.  R-Values talk about the movement of heat.  What are U-Values?

A U-Value is a unit of measure that is almost always applied to windows whereas R-Values are thought of when talking about Insulation.  Yes, they can be used interchangeably but that seldom happens.  R-Values are for Resistance of Insulation and U-Values talk about windows and how windows conduct heat.

A U-Value measurers the performance of windows and how well they transmit heat.  So, the lower a U-Value the poorer that window transmits heat.  All this is sort of the opposite of R-Values. 

When talking about an R-Value a high score such as an exterior wall of R-30 performs well because it Resists Heat transfer; and therefore is good insulation.

When talking about a U-Value a low score for a window is good because the various windows conducts heat poorly.  The U-Value indicates how much heat is lost.  If you have a window with a U-Value of 0.30 you will have met the Vermont Energy Code requirement for a good window.  However, that does not mean you have a particularly good window.

A good window, one that transfers heat poorly, will have a U-Value of 0.21 or lower.  Remember when talking about windows it is like golf; low score wins.  When talking about insulation a high score wins.

Today’s photograph shows you what you typically can’t see – the three panes of glass in your new triple pane window.

To achieve a low U-Value score of 0.21 or even better it is necessary to use a Triple Pane window.  Using three panes of glass creates two sealed chambers where Krypton Gas is used rather than Argon Gas.  Argon gas is used in spaces of ½” whereas Krypton is used in spaces of 3/8”.  Dense Krypton Gas transmits less heat than does Argon.  Hence a Triple Pane window performs much better.

Whether you live in Mendon, Vermont or Morgan, Vermont it is a great idea to build your new home with high performing windows.  Vermont Modular uses Triple Pane windows all the time!

So, don’t confuse R-Values and U-Values!  Be sure your home is highly efficient!

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