For Independent House, low cost options include among others:
Replacing CFL and incandescent bulbs with LEDs. Light bulbs are used every day of the year so the savings are pretty significant. LED prices are cost effective and the small premium paid to obtain a LED is recovered within a year! Link to Lighting Calculator
Replacing an old ceiling fan with a BEE * star rated ceiling fan. This appliance is used almost every day. The savings within a year pay for the additional cost incurred in the purchase of the ceiling fan. Link to Ceiling Fan Calculator
Using khus curtains to keep the rooms cooler in summer
Consider Solar Powered Lighting for outdoor areas like Garden and Walkways.
Install an overhead tank overflow alarm system to save water and electricity. The added benefits are that the roof and walls are not damaged due to water overflow!