Improvement of energy saving and indoor air quality by using a spot mixing ventilation (SMV) system in a classroom

Thermal comfort, energy saving, and room air quality are widely affected by the flow behavior in the occupied zone. In this paper, the concept of a spot mixing ventilation (SMV) system, which aims to supply cold fresh air directly to the occupant seating is developed and examined numerically for use in a typical classroom. Consequently, a proposed SMV system for the classroom was installed over each seated occupant at ceiling level. Occupant’s thermal comfort and energy enhancement were used as the main evaluation index which was employed to assess the performance of the proposed SMV system. The validated computational fluid dynamic (CFD) model was employed in this examination. Four different values of supply temperature, 19 °C, 20 °C, 21 °C, and 22 °C, were examined numerically to evaluate the occupant’s thermal comfort and energy enhancement in the investigated classroom with and without using the SMV system. The results show that the SMV system can reduce the energy demanded by the cooling coil from 4.522 kW as in cases 1, and 2–1.206 kW, 0.9045 kW, and 0.603 kW as in cases 3, 4, and 5 respectively. Furthermore, the SMV system was able to improve the quality of the indoor air by supplying fresh air directly to the seated occupants. It can be concluded that using the SMV concept can provide a significant enhancement in indoor thermal comfort and save more energy.