Ventilation is important, winter and summer. In Texas, your summers will be very important. Chickens normally handle cold much better than hot. But you still need good ventilation in the winter to get rid of excess moisture and ammonia build-up.
The way I get good ventilation is to have the permanent openings at the top of the coop, well above the roosts. It depends on how your coop is built, but I suggest having overhangs where you can to keep the rain out and have openings under those. Cover them with hardware cloth to keep predators from climbing in. Roof vents and such can also work, unless they get covered in snow. A breeze blowing above the chickens while they are roosting does not bother me. It's just a breeze hitting them that can cause a problem.
During the hot weather, have a window or two or some other vent you can close in winter, also covered with hardware cloth to keep predators out. Even a couple where they get a cross breeze won't hurt in the summer. Wind chill is only a factor when the weather is cold.
I don't know where you are in Texas. There is a difference in Corpus and Amarillo. Many people along the Gulf Coast use those three sided coops 7L is talking about year round and some of those places will see below freezing. Just put the roost in where it is pretty well protected from direct breezes.
Growing up, we had some chickens that slept in trees in pretty cold weather. These were pretty dense trees in a protected valley, so maybe the breeze was not hitting them as much as you might think, but yes, chickens can handle cold better than heat.
