Carbon monoxide (CO) gas can bind to hemoglobin in blood cells. Even if humans inhale CO gas at high levels, reaching 25 parts in a million (PPM) (PER.13 / MEN / X / 2011), the risk is death. Besides CO, there are other odorless and colorless gases, namely carbon dioxide (CO2). Exposure to high levels of CO2 concentrations reaching 1000 PPM or more can be bad (American ASHRAE 62-1989). Many individuals or groups in large buildings do not know the weather conditions outside because the building is too large and there are no windows to view the weather outside the building. This happens a lot in malls or large shopping centers. By utilizing the concept of internet of things (IoT) technology and Android applications, real-time remote monitoring can be realized.