Hereś the proposed DBH calculator to be used to see if your proposed NEW, LARGE dwelling complies with the new energy efficiency standard for hot water. (No BluePeter, this does not apply to your retrofit, although your retrofit cannot make the efficiency worse than it was before you started. However, you do not have to meet the new code.) This calculator allows for a bewildering choice of technologies and combinations in putting a hot water system together. Only in the absolute worst case, when the hot water cylinder is the most inefficient type, would you need a 6 litre/min shower head. No plumber worth his salt would be doing it that way in any case, so the point is almost moot.

Where we come unstuck, and where Smith and Co. have done a real good job of misinformation, is with the Acceptable Solution. Acceptable Solutions are the lazy manś way of complying to the H1 Building Code. They offer a worst case, rule of thumb guide for those who either cannot or will not use the free calculator. Here is the proposed Acceptable Solution document that DBH is consulting on and which has been falsely called a regulation. Section 5.2 is for the lazy man who cannot be bothered using the calculator. For this reason, the compliance table uses the worst case data from the calculator and says – Beat that! Itś this worst case scenario that Smith and Co. are erroneously calling the new nanny state regulation.

Here are some facts to digest:

80% of all hot water used in homes goes for showers

Out of approximately 1.6 million homes in NZ, 460,000 have high pressure water systems.

This means that  71% of existing homes already have a low-flow shower! (And they are not complaining either.)

If just a third of the high pressure systems in NZ were to switch to a high efficiency shower head of between 6 and 9 litres/min, they would each save on average 1500 kWhs per year, or about $300. They would also collectively save enough power each year to run the entire city of Nelson for that same year. This is not small peanuts. And we don’t need to go to 6 litre/min shower heads to do it!