Is Installing Thermostat can reduce the electricity costs?

A smart thermostat could reduce AC and heating when people are out of the house for example. It could set different temperatures when people are asleep compared to when people are awake.

That would make people use even more electricity by replacing stringent use of the off switch with complacency. On the other hand if your family is already lazy with the off switch, then it will save you electricity!

Or if you currently tolerate rooms that are overly warm, a better thermostat will definitely help you save electricity by maintaining the heat at the minimum comfortable level.

I have heard of that concept, but I never understood how it was supposed to work. It is a lot more certain to save money by improving insulation. I bought 2" thick Styrofoam board at the lumber yard, cut it and stuck it to exposed parts of the foundation. Fifty bux worth of Styrofoam reduced my heating cost to ONE THIRD of its former value.

Count the switches and outlets on outside walls and get insulators at the hardware store. Find all the cracks around windows and seal them with glue (Elmer's). Get a roll of bubble wrap and put a few layers on windows. Spray the glass with water and the plastic will stick to it.

That's all good advice.
But with the cling wrap on the windows, try to do it by leaving a gap in between the window and the cling wrap - much much more effective!