Green building explained: Are you in hot water?
Hot water is one of the biggest energy guzzlers in the home. Here are two ways to use hot water smarter
Reading about the NZ First Light home earlier in the week, we noticed a couple of nifty things they’d included from Australian company Leap Australasia. For example, The First Light house has 40 evacuated tube solar collectors that use energy from the sun to heat water for all of the houses hot water needs.
Evacuated tubes: how they work
Leap’s evacuated tubes have a vacuum that acts as a super-efficient heat trap. Heat pipes located within the evacuated tubes conduct the heat trapped within the tube up to heat water.
The copper heat pipes are also evacuated and attached to aluminiumnitride heat fins to maximise solar energy absorption and heat transfer. On a sunny day, these heat fins and heat pipes can exceed 150° C very quickly.
As the heat is conducted to the top of the solar panel, a solar controller senses the rise in temperature and moves water to the panel to be heated. The heated water is then circulated back to a storage hot water cylinder.
A circulating pump moves the water to and from the panel. The system's solar controller and circulating pump together with any auxiliary heating keeps water in the hot water cylinder at a constant temperature - ensuring you have a reliable supply of hot water heated by the sun.