My short commute is only 1.75miles but through experimentation I've found pleasant alternatives; ironically I had took one of my shorter routes when Wednesdays events happened as soon as I get my bike fixed I'll be revising some of those routes. I wear my work shirt and trousers for my shorter commutes and wear a cycling shirt in addition to the work trousers for a longer one unless its really cold and I can get away with the work shirt. IIRC my Iongest commute (33miles) was in a short sleeved work shirt on one of the snow days (been that many its hard to put a date on it) in the pancake fens on a still day and there was no resistance to build up a sweat.