Having the correct heat pump installed it will conservatively save you about 50% (average throughout the year) of your water heating cost which constitutes around 40% of your overall electricity consumption. However while installing a heat pump will certainly save you energy, the difficult will be to quantifying the actual amount that will be saved up front. While a very good educated guess can be made the savings have a direct bearing on the amount of hot water you use, the COP of the heat pump you install, your personal usage pattern and more importantly the lifestyle you are willing to change.
One of the most important factors that is overlooked with respect to effectiveness or efficiency of heat pump system or any renewable energy is the human factor. Human beings are creatures of habit and as a whole we find it difficult to change or make that life style change to accommodate the necessary changes.
We simply find it difficult to change our habits.
A heat pump is just a tool that provides hot water savings, however the optimum effectiveness or efficiency of the heat pump is also dependent on whether we are willing to change our life style in order to achieve the optimum savings. It is important to note that your habits of hot water usage or lifestyle will most likely have to change, to achieve the optimum performance from a heat pump.
As result of a heat pump producing hot water through extracting heat energy from the environment and not from direct solar radiation (sunlight), the life
style change is not as great with a heat pump as it is with a solar water heater.