About this site

If you go looking for what a hot water system costs to run in Australia, you find four kinds of source and none of them is quite what you wanted.

• Installer and manufacturer sites have calculators, and every one of them is a lead form with arithmetic attached. The defaults flatter the product being sold.
• Government material is accurate and static — good tables, usually for one state, published as a PDF, with no way to put your own numbers in.
• Comparison sites are built for switching energy plans and treat appliances as an afterthought, often with figures imported from overseas.
• Overseas tools are frequently excellent and entirely irrelevant, because they model different prices, different climates and different rebates.

What was missing was something interactive, Australian, and not selling anything. That is the gap this site is built for.

It personalises

Set your state, your household and — if you want — the rates off your own bill, once. Every calculator, table and worked example on the site recalculates for you, and follows you from page to page. There is no account, and the settings never leave your browser.

It shows the working

Every system in the hot water calculator opens to reveal the whole calculation: heat required, losses, efficiency applied, price per unit. The methodology page lists every constant with its source and the date it was checked.

It is validated against something

Both the hot water and the heating and cooling models reproduce Sustainability Victoria's published Melbourne running costs — twenty-two separate figures across the two, almost all within two per cent — and that comparison is re-run automatically every time the site is rebuilt. It is the only claim of accuracy on this site that you can check without taking our word for anything.

It says the inconvenient thing

A gas water heater currently produces fewer emissions than a heat pump in most of Australia, because most of the grid is still dirty. Gas instantaneous beats a heat pump on cost in South Australia and the ACT. A heat pump replacing an electric tank already on off-peak saves far less than the marketing implies. All three are on this site, prominently, because a calculator you can catch being convenient is a calculator you cannot use for anything.

One person in Australia, working on it outside a full-time job. That is worth knowing for two reasons: it means there is no commercial relationship with any installer, retailer or manufacturer to disclose, and it means corrections are handled by the person who wrote the thing rather than disappearing into a support queue.

It also means the reason to trust the figures is not credentials. It is that every one of them is sourced and dated on the methodology page, and that the model is checked against an independent benchmark. That is a better basis for trust than a byline anyway.

Advertising, and in future affiliate links that will be labelled wherever they appear. Nobody pays to appear in a comparison, no result is sponsored, and no installer, retailer or manufacturer has any relationship with this site. The disclosure page sets out exactly how it works and what would have to change for that to stop being true.

Hot water and appliances are the first two modules. The planned order after that is solar payback, then reverse cycle heating and cooling, then a plan comparison helper — chosen because each one feeds the others: solar changes what a heat pump costs to run, and reverse cycle heating is the same technology as a heat pump water heater applied to a room.

There is no timeline, because this is a side project and promising dates would be the first inaccurate thing on the site.

EV Running Cost does the same job for electric cars in Australia — charging costs, running costs and the comparison against petrol, built on the same principle that every default figure should be sourced and every one of them should be yours to change.