Although air-conditioning has played a positive role for economic development in warm climates, its image is glob-
ally mixed. Field studies demonstrate that there are substantial numbers of dissatis甧d people in many buildings,
among them those su€ering from Sick Building Syndrome (SBS) symptoms, even though existing standards and
guidelines are met. A paradigm shift from rather mediocre to excellent indoor environments is foreseen in the 21st
century. Based on existing information and on new research results, 畍e principles are suggested as elements behind a
new philosophy of excellence: better indoor air quality increases productivity and decreases SBS symptoms; unneces-
sary indoor pollution sources should be avoided; the air should be served cool and dry to the occupants; ``personalized
air'', i.e. a small amount of clean air, should be served gently, close to the breathing zone of each individual; individual
control of the thermal environment should be provided. These principles of excellence are compatible with energy
e乧iency and sustainability. # 2001 Elsevier Science Ltd and IIR. All rights reserved.