Abstract
The learning efficiency of university students has been unsatisfactory due to the poor environmental control in the classroom during early and late of the semesters. Since it is well-known that large amount of cost and energy is required to maintain comfortable Indoor Environmental Quality (IEQ) in university classroom for the operation of HVAC system, university authorities require basic guideline to be provided for their decision making on maintenance of optimum IEQ. This research is performed to provide the basic information that can be used for establishing IEQ standards. Learning efficiency of students depending on changes in physical variables is investigated by surveying 45 students during two semesters (from fall 2011 to spring 2012). The physical variables in university classroom was 1) temperature variation of 14.7 to $26.7^{\circ}C$, 2) relative humidity of 25.3~70.1%, 3) air motion of 0~0.3m/s, 4) $CO_2$ concentration of 739~2003ppm, 5) illumination intensity of 376~630lux, and 6) noise level of 54.9 ~64.8dB. The average day temperature of outdoor during two semesters varied from 2.0 to $24.4^{\circ}C$. According to the results from this surveying, the variable that affects mostly on learning efficiency of the students was thermal comport followed by $CO_2$concentration, illumination, and noise level. About 75% of students showed higher learning efficiency in room temperature range of $18{\sim}23^{\circ}C$. The result was quite different from known thermally comfortable temperature range of $22{\sim}26^{\circ}C$ in the office. Further research is necessary on modifying the environmental standards for university classroom for higher learning efficiency.
