Almost all multi-storey buildings, hospitals and shopping malls are equipped with central air conditioning. Sensors are installed that detect the amount of humidity and temperature outside and inside the building and then work accordingly to provide comfort. Most air handlers installed inside a building use outside air to keep the building's air healthy as maintaining health is also essential. The amount of air is also regulated by detecting the occupancy level inside the building. This HVAC system is basically based on the time of day, temperature, humidity, pressure and the presence of people inside it. Different types of glass are available which change their shade depending on the time of day and thus lead to an almost 30% reduction in solar heat