Oct 6

Windows & Glass Performance, Part 2

Tuesday, October 6th, 2009 | posted by: Chip

Window and glass type decisions should be made based on the application.   You may live in a climate where your main concern is keeping the cold out and the heat in your home.   Others, like me, are mainly concerned with keeping the heat out and the cool in.   Cold weather climates and hot weather climates each create a   unique demand on windows.   The orientation of your home, the number of windows in a room, the amount of time the window receives direct sunlight, and the size of the window will all affect window performance.   On top of that, windows alone are not always the answer for improving indoor air quality.   Your mechanical system (A/C & Heat) have a significant role in that.

For most of us it is best to start by answering a few questions.   Do you need windows for new construction such as a new home or addition? Do you want to replace your existing windows with new windows?   Do you just need a little caulking and weathering on your existing windows?   Are your   window frames good but you want better energy performing glass in them? Your answer is your starting point.   A word of caution, this is the point where the limits on window performance are in play.   New windows installed in new construction are part of the entire construction shell.   Indoor air comfort is a combination of the entire shell and your mechanical system.   If you caulk and install weatherstripping to existing windows you   may not significantly improve indoor air comfort because the glass is the same and   existing construction shell and mechanical system have remained the same.   Assuming the caulking and the weather stripping are good, replacing existing glass with energy efficient glass will improve the glass performance but overall performance is reliant on the existing construction shell and mechanical system.   The existing conditions may be fine and therefore caulking, weathering and glass replacement may be all you need.   In almost all circumstances replacing and upgrading the existing glass in your windows is significantly less costly than replacing the entire window system.     Again, there are limitations and a new window system is not a panacea in itself.

In my next post we will discuss how to start making the decisions that are right for you.

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