Of course Energy Savings and Comfort are two very important criteria as you determine the best replacement window and patio door type and brand for your project.  But how do you compare the ability of the different types, styles and prices of windows to deliver on that important objective?  Vinyl clad wood windows, Metal windows, and Vinyl windows vary greatly in how they provide energy savings and comfort. In fact windows made of the same frame materials, like the vinyl windows we design and manufacture here at Jantek Windows can vary greatly in energy and comfort performance from those of other manufacturers. So how do you compare your options with regard to this important criteria?  In this article I will give you a simple way to compare the insulation value of any window or patio door your are considering. All you need is one number and a calculator. Let’s get started.