There are four types of windows these days to select from.

1. Aluminum Clad Wood
2. Aluminum
3. Vinyl
4. Fiberglass

Each has pros and cons and here has been our experience.

1. Aluminum Clad Wood are generally the most expensive. Traditionally, they come in specific sizes and if any customization was required, they cost about 50% more at a minimum. They require paint or varnish on the wood surfaces (inside) but are often the best to look at from the inside as a result. Their durability is very good but as they are a natural product subject to decay where the others are not. Wood is also and excellent insulator so this frame type in combination with a good window can have excellent thermal properties. These windows however cannot be used in situations where there is constant wind such as mid-rise buildings as they will eventually warp. Aluminum is a paintable and any color window is possible.

2. Aluminum windows are less expensive than the others except for vinyl. They are strong, have very low maintenance, and require no painting. Their disadvantage is that they have poor thermal properties. Aluminum is conducts heat and cool and as a result, energy bills are higher and there may be condensation on the inside aluminum surface. Some of this problem can be alleviated by installing the window in such a way to minimize the contact between cold surfaces such as brick and the window but one cannot completely insure against it. Some manufactures are better than others and creating a thermal break in the window but it's hard to know from looking at a window whether the thermal break will be effective. Aluminum is a paintable and any color window is possible.

3.Vinyl windows are the least expensive windows of the four types. They have come a long way and today many are well made. They hold up well and function smoothly. Their thermal properties are excellent. They cannot be used where high strength is required (mid-rises) but their major short coming is aesthetic. Vinyl just doesn't scream quality and in addition they don't come in dark colors. Some manufactures make them in dark colors but I don't trust them yet. Vinyl expands when hit by the sun and dark vinyl expands more. I'm not sure that over time these darker windows won't fail. In Canada, they have created vinyl windows that can be painted any color -- usually vinyl doesn't paint well. But again, that's Canada where there's less sunlight. No one can say for sure those windows will hold up in Chicago. Overall though, I like vinyl windows and use them where ever aesthetic considerations allow.

4. Fiberglass windows. These marry some of the best properties of vinyl and aluminum. They are strong, very durable, come in dark colors and almost have the thermal properties of vinyl. They are less expensive than wood clad when custom sizing is required. We tried a Pella version of these and other than the fact that their hardware was funky they have performed well.
Other things to consider when buying windows are the thermal qualities of the panes. These are now rated and some double pane glass is far superior to other. Much has to do with the element that separates the glass panes. Metal separators have more thermal conduction.
Argon-filled double pane glass is a feature available in better windows. I'm not sure how much of the argon get in between the panes. I went to a factory to watch the procedure and wasn't sure it was really working. Theoretically, they have better insulation properties.
Low-E is another selling point. Some sources say this protects your furniture from UV light damage. Others have said it allows less energy transmission and so have better thermal properties. The cost is relatively small and we generally use low-e glass though I'm not certain of the overall effect. Certainly a low-e glass in an aluminum window will have more heat conduction than a non-low e in a vinyl window.

Feel free to e-mail comments or questions to info@Stratagemconstruction.com