First determine the ideal temperature and climate conditions. Then, if the ideal is cooler than the current temp, wear the same clothes twice as long between washings; if the ideal is warmer than the current temp, wear them half as many times. But I cannot overstate the importance of Step 1 before taking a potentially irreversible action. Coup de Grace: Apply the same calculus to your every energy-consuming/heat-generating activity, and lather/rinse/repeat (metaphorically).