‘Desi AC’: Jhansi school student built budget air conditioner for ₹1,800, can drop room temperature by 5°C. Jhansi: Class 12 student Kalyani Srivastava once built an air conditioner for just ₹1,800 which could reportedly cool down a room by 4-5°C in an hour. Her invention reportedly made it to a national-level competition linked with IIT Delhi.