From the Aborus Efficiency Journal, a new post on the importance of window frames to window performance:
So how do we get the most out of our windows? Specify larger windows, and use simulated divided-lites to maintain the appearance of smaller windows where desired. Specify better thermal breaks, and swap out the aluminum edge spacer with steel or with insulating foamed rubber. Your building will use less energy, feel more comfortable, and your windows will be less likely to suffer from condensation.