Every home needs hot water, every day. Heating water is almost always the single biggest user of energy in a home because unlike room heating (often the 2nd biggest user) water heating uses energy all year.
The average new home in New Zealand devotes around 45 per cent of its energy consumption to heating water. As such, the hot water system is one of the most important to get as energy-efficient and sustainable as possible, not just to reduce your bills—achieving savings of up to 80 per cent—but to minimise your personal impact on the environment.
How much energy does water heating use?
This varies a lot by household and with different people’s routines.
In a new home with modern appliances, good levels of insulation and efficient space heating it will be around 45% of the annual power bills.
A dated and conservative figure of 30% is often used but this includes all existing homes with comparatively high energy use from inefficient heating and insulation.
As an example, you can work out roughly how much energy your hot water uses. Each person uses around 50L of hot water per day, so a family of 4 uses an average of 200L per day, 73,000L per year. This requires around 3,995kWh of heating energy, or 999kWh per person per year. Multiple this by the number of people in your home for an indication of the annual energy used for hot water. Then compare this to your total annual power use for your family’s hot water percentage.
Some electricity bills have a controlled meter reading, this is usually your hot water cylinder so check your bill for your water heating energy use, if you have an electric cylinder