ENVIRONMENTAL BENEFITS

Electric water heating is the biggest contributor to household greenhouse gas emissions, accounting for around 25% of the average homes carbon footprint. Solar water heating is one of the easiest high impact eco solutions available. Compared to electric water heaters, it significantly reduces CO2 immediately by an amount equivalent to taking the family car off the road, and reduces around 30% of the domestic power bill per year. A family home's average carbon footprint is 11 tonnes of CO2 per year. A solar hot water heater can reduce this by 4.5 tonnes. If every home in Australia switched to solar hot water we would reduce our national carbon emissions by 5% annually.

The use of solar hot water is rapidly increasing, resulting from a combination of growing desire to be green and from legislation that requires the replacement of electric hot water systems. Given that around 40% of household electricity is spent on heating hot water when electric hot water systems are used, the predicted large rises in electricity prices will see many users converting to solar hot water.

The ecological value of solar hot water systems has been acknowledged by governments at all levels through increasingly generous rebates.

The first commercial solar hot water systems appeared in 1891. Its principle of putting water in tubes under glass to be heated by the sun and then stored in a tank is still the most popular form of solar hot water heating. This type of system is called "flat-plate" because of the large glass plate over the water-filled tubes. A new type of solar hot water system emerged in the 1970's. Invented in Australia, it uses vacuum tubes to generate heat rather than having the sun heat the water directly. These systems are called "evacuated tube" systems.

Solar water heating is far better than instantaneous gas water heating if you consider the effect on the environment. Instantaneous gas water heaters are initially cheaper to install but they do burn gas and this releases greenhouse gases. Over the first 10 years solar and gas are currently about the same total cost. However, the combination of much lower greenhouse gas production and likely superior longevity makes the choice of solar hot water a better one from all perspectives.

The best way to evaluate a hot water system is to look at the whole of life costs of the system and the effect on the environment. In the future the cost of polluting carbon will increase the overall cost of systems that produce greenhouse gases.

Solar is the best option to obtain low heating bills and it directly contributes to a cleaner environment. Solar hot water will help us meet our greenhouse reduction targets.

The Australian Greenhouse Office table below shows the yearly emissions of greenhouse gas for different types of hot water heating: