Building systems and HVAC are the machines that make a large building usable: its cooling, its lifts, its locks and its fire alarms, together with the software that runs them. HVAC stands for heating, ventilation and air conditioning. In India, it mostly means cooling.
Take, for example, a shopping mall in Surat on a Saturday in May. Outside, the temperature is 40°C. Inside, it is 24°C, because the HVAC plant in the basement and on the roof removes heat from the whole building. Shoppers ride the lifts and escalators between five floors. Shop staff open the service doors at the back with their cards, through electronic door locks. In every ceiling, a smoke detector of the fire alarm system checks the air for smoke.
Each of these systems comes from its own makers, and a different contractor usually installs each one. A building automation system (BAS) connects them, so that the mall's engineers can watch and control everything from one screen. The BAS starts the cooling an hour before the mall opens and slows it down after closing. If a smoke detector goes off, the BAS stops the fans that would spread the smoke, sends the lifts to the ground floor and unlocks the exit doors.
Who buys this equipment? Property developers and building owners buy it, usually through the contractors who install it. The makers are large global engineering groups. They earn money twice: once when they sell a machine, and then for decades from maintenance contracts. In India, a lift is usually serviced under an annual maintenance contract (AMC) for as long as it runs.
The machines are now connected to the internet, and they report their own condition to their makers. This is the industrial Internet of Things (IIoT). It lets a maker find a worn part from far away and replace it before it fails. This is called predictive maintenance. The same makers also build the cooling for the halls full of servers described in data centre power and cooling.