I have fixed up several homes, and obtained a good education doing so. My current home has received some special focus, and has an electric bill about 20% of that of most persons on my street. Here are some examples:
This Power Pipe Drain Water Heat Recovery System in my basement extracts about 60% of the heat from shower water going down any drain in the house (also dishwasher); no moving parts; cold water from city comes in bottom of outer coil, is preheated by drain water and then goes to hot water tank.
Simple and effective. Small natural gas boiler unit has 95% efficiency; heats radiator water for house and domestic hot water; saves a ton of money.
Its more than that.
I even ride a push scooter to the University and around town, it saves me about half the time compared to walking and is great exercise. It collapsed down to a very compact form easily carried into stores, restaurants etc. All the rage in some European cities like Berlin.
A cottage I renovated from top to bottom:
Do it yourself, as much as you can and learn.