Development of Indoor Comfort Zone Control System

Abstract

This research introduces the feasibility study of developing the indoor comfort zone control system of a building which controls temperature, relative humidity and the speed of the wind affecting a body to create a comfort condition in the room according to the ASHRAE 55 standard. This control system applies a microcontroller to control the operation of a ventilation fan, an exhaust fan, an air circulating fan and a dehumidifier. The criteria to specify a comfort zone must have operative temperature of 24 - 27 °C , relative humidity of 50 - 70 %RH and air speed of 0.2 - 1.0 m/s. There are temperature, humidity and smoke sensors installed both inside and outside of the room by which the control data are measured. The key working conditions of the system is to maneuver ventilation and exhaust fans to exchange air between inside and outside the room so that the temperature inside the room is less or equal to the temperature outside the room at all times. The dehumidifier performs until the air in the room meets the relative humidity requirements. If smoke occurs in the room, the exhaust fan must immediately blow the smoke out from the room. The experiment results show that the comfort zone control system can be control the relative humidity less than 75%RH. This control system can achieve the comfort zone in the test room according to ASHRAE Standard 55 only when the outdoor temperature was less than or equal to 27 degrees Celsius. Therefore, the comfort control system will only work well in winter or partly in rainy season. In the summer season, Although the control system is not suitable for the summer weather, it can reduce the cooling load of the air conditioning when the indoor temperature higher than the outside temperature.