When people using the interior space to breath the fresh air and have high efficiency for working, they are actually inside the Plant Cyborg's stomach. Inside the stomach, there is an water bladder that punch water into several organs, the organs have plants living on its surfaces that will absorb the water and nutrition from organs. The plants will produce O2 to attract people coming inside to stay and than they will have the CO2 meal from human. 

Using CO2 sensor to alternate the lighting temperature, different color of lighting will change the activity inside the space. White light is for people to work inside, UV light is to wake up the plants and tell them it's time for a meal.