When you have eliminated major sources of heat loss from your house by installing double glazing, cavity wall insulation and loft insulation and the more obvious sources of energy loss by fitting low energy light bulbs, draught excluders to your front and back doors, replacing your old style cathode ray tube (crt) television with a liquid crystal display television, hanging clothes out to dry instead of using a tumble dryer. you must turn to smaller things if you want to waste less energy.
These may include:
Using a table top hot drinks flask. Instead of boiling water each time you want to make a cup of tea/coffee, boil enough water at once for several cups and store the tea/coffee in the flask to be poured at will. A flask used in this way can be much more insulating than a kettle, and using one means that the kettle does not have to be heated each time.
Use a spray implement at the end of your mixer taps. This mixes water and air. The water is typically heated part of the time. If you mix in air with it, less water has to be heated, and the spray implement can be swivelled to aid in cleaning.
Fit sheets of aluminium reflecting material behind some of your radiators. If the radiator is fitted to an outward facing wall, some of the heat will be lost to the outside. Fitting a reflecting sheet behind your radiator means that some of this heat is reflected back into the room so not lost to the outside.
Fit remote control plugs to some of your plug sockets. Many of your electronic devices will be constantly on standby. It can be too much effort to switch them off one by one, or hard to reach the plug socket to switch them all off at one if they are connected to a multisocket. If you fit a remote control plug however they can all be switched off at once with a single click as you leave the room.
You can use less energy in cooking by using a pressure cooker, which cooks food at a higher temperature, reducing the cooking time, or making more use of a microwave, which acts directly to heat the water molecules in food, and not the cooker itself, and bounces the microwaves about repeatedly inside the container ensuring that as much of the energy as possibly is used to heat the food.
Fit push light switches. These can be set to switch off automatically after a few minutes. Many lights are left on constantly for want of the effort to switch them off.
Fit curtains to all the windows and draw the curtains after sunset. This will reduce heat radiation leaving the room.
Put rugs on the floor to reduce heat loss through the floor.
In addition to this you can monitor your use of electricity in real time using smart energy monitors. You can then see which of your electrical appliances use the most energy, and possibly work out how to reduce their use.