Dayananda Sagar College of Engineering, the college I am a part of currently, conducted an open themed 16-hour hackathon for the Computer Science Engineering students of the college during March 2016. Mostly people from the second and third year were participating, with me being the only kid from the first year.
I wanted to build a product roughly in the IoT area, a mentor from DERBI, a entrepreneurship cell in my college, suggested that I try to show him a fully functional IoT stack, I agreed and started with one.
HackIndia had thought me a thing or two about IoT, in this demo, I had 2 LEDs that represented the state of bulbs in 2 rooms, the LEDs were connected to a laptop which was in turn connected to the Internet. I had a separate circuit built with just a motion sensor, it was connected to a different laptop and sent requests to turn on/off the LEDs that were connected to the first laptop. Apart from the motion sensor, you could also change the state of the switches with the help of an Android app we quickly wrote from scratch, it also sent requests to the LED connected laptop. This was all possible because of a web server running on the first laptop, we made a front end for this server and this allowed you to switch the LEDs from the computer too. So you had like 3 toggle-able access points per LED, you could easily replace the LED with an actual household appliance with a single channel relay per appliance.
This allows you to control your home appliances with the help of technology, you could potentially scale this system to detect movement and in the absence of any, you could automatically switch off all the lights in the house to save electricity. In order to improve the product, you could potentially add thermos-sensors so that you could know the temperature of the room, and alter the speed of the fan to match a given user temperature, you could also add light sensors so that you could dim lights that are in the presence of natural sunlight. Adding Google's Nest API support would go a long way in helping new devices interact with the existing IoT stack, most of the toggling could be handled through the Nest API, we therefore do not need to build client side interfaces to the user.
Right now this was built with an Arduino as it was just a demo, if you were to implement this to scale, you'll ideally want to look at ESP8266 with a strong base signal so that you can do peer-2-peer control of the appliances, it'll also work out significantly cheaper. The cost-barrier to entry to a product that'll be built with an ESP8266 could be as low as Rs. 350 per appliance at home, that's Rs. 280 for the ESP8266 and Rs. 70 for the single channel relay.
The judges were impressed with my product and I was placed First in this hackathon, I received a medal, a certificate and an Amazon gift voucher of Rs. 1000.