Even in the well-accepted indoor temperature range of 20-24°C (68-75°F), people can experience thermal discomfort. Complaints about the indoor thermal environment are one of the major complaints building and facility managers have to deal with, and they spend a large amount of their time and money to solve them. People spend more than 80% of their time in buildings. Therefore a good thermal comfort and quality of the indoor environment are essential for their wellbeing, health and productivity.