Energy saving and efficiency are some of the main topics used in the modern world to promote the increase of sustainability and reduce pollution produced by the generation of fossil fueled powered electricity. The main goal of this study is to assess indoor air quality and determine energy efficiency, in a study room, using plants. The plant used for the research was the Spathiphyllum, best known as peace lily. Air conditioning systems have a purpose of ventilation or air refreshment, and temperature control. The function of ventilation is to reduce CO2 concentrations in enclosed spaces. CO2 is a known indoor pollutant affecting performance in the workplace, at school, and offices around the world. Extreme levels of CO2 may be harmful to health and safety of individuals. Levels of CO2 in the range of 800 ppm and 2,500 ppm in the office and classroom have been found to decrease concentration and performance, and rates of absenteeism. Indoor plants play an important role in lowering indoor CO2 levels, hence reducing the energy requirements of the buildings. For this research, plants were added to the room EDI 146 at the engineering building with the aim of lowering the CO2 levels produced by students’ breaths and low ventilation. One plant was added for every hundred square feet with a total of seven plants. CO2 levels were measured in the room throughout seven months, other factors were considered such as number of people in the room, air temperature, wet bulb temperature, temperature and relative humidity.