If three appliances are replaced, a hot water heater, an oven?
It really depends on the country, technology and regulations. Consumers and the free market dont really drive up efficiency. People tend to prefer to waste energy and have a more flexible product. For example a fridge or an oven can be larger if you use less insulation, this means you can cook a larger Turkey but it costs a little more to run. In the EU, large improvements in efficiency have only occured through regulation. Fridges and lighting now consumer 1/10th the energy they used to consume. Certain countries have regulated insulation on water heaters, but this can often always be added after. For clothes it is ultimately more efficient to dry clothes outside, or even just hanging in a room, it takes longer inside though. Good luck with your homework and look up what regulation are in force in your country and when they came into force.