It’s not the heat, it’s the humidity. The cool temps in libraries are a side-effect of the primary reason for the A/C: to keep books from getting moist. Mold & mildew thrive in moist environments, and when they thrive, they destroy paper. Too keep the books dry, libraries run the A/C a little more than humans like. Keeping paper dry, in fact, was the reason behind the invention of the first A/C by Willis Carrier – read about it here: bit.ly/Atlantic-AC. Ever notice how the stereotypical librarian image involves a cardigan? Brrr! Librarians agree!