I'm surprised they are only an option there. They are required by code in Dallas.

They do work and with UV blockers they also protect your furniture and hardwoods from the bleaching effects of the sun.

See link at bottom for a good, basic explanation.

Here is a link that might be useful: Low E windoes

Thanks for the response. Is it only required in Dallas from an energy saving perspective? Since I'm in the Chicago area, it looks like, according to the article you posted, that I should get the moderate gain windows. I'd be afraid I would be trapping warm air IN the townhome which would thereby actually raise my AC costs in the summer...

Mike

You will block more solar gain in the summer with low-E windows. I live in Columbus,ohio and switched out older double pane windows for new double pane with the low-E coating and have seen a BIG difference in summer air conditioning and winter heating costs. You don't trap warm air inside the house with low-e windows. You block the heat gain from the sun beating on the windows. Unless your house is in total shade constantly,you will benefit from low-e windows

Low-E windows make a difference, in both heating and cooling climates. One of the first upgrades we recommend to builders when we run an analysis on their homes.

A lot of misunderstanding about this but it does work year round. Simply put Low-e reflects heat so in the winter it will reflect the heat back into your home and in the summer it will reflect it out. Northern climates where heating is a primary you want a high solar heat gain to use the suns free energy. In southern or mostly cooling climates you want lower solar heat gains.