Every human being,no matter what he is doing,gives off body heat.The usual problem is how to get rid of it.But the designers of the Johnstown campus of the University of Pittsburgh set themselves the opposite problem-how to collect body heat.They have designed a collection system which uses not only body heat,but the heat given off by such objects as light bulbs and refrigerators as welt.The system works so well that no fuel is needed to make the campus' six buildings comfortable.     Some parts of most modern buildings--theaters and offices as well as classrooms-are more than sufficiently heated by people and lights and sometimes must be air conditioned even in winter.The technique of saving heat and redistributing it is called "heat recovery".A few modem buildings recover heat,but the University's system is the first to recover heat from buildings and reuse it in others.    Along the way, Pitt has learned a great deal about some of its producers.The harder a student studies the more heat his body gives off.Male students send out more heat than female students and the larger a student,the more heat he produces.It is tempting to conclude that  _ for the Johnstown campus would be a hard-working overweight male genius . The technique of heat recovery is used  _  .
to produce a special form of air-conditioning to provide heat for the hot water system to find out the source of heat to collect and reuse heat