A lot of activities get labelled as 'sustainable' these days, despite having a hidden subsidy of non-renewable resources or energy. The only truly sustainable energy source is the sun and the various manifestations of that energy such as biomass, wind etc. The rate and method (technology) used to harness or extract that energy determines it's long term sustainability. Wind turbines constructed from huge volumes of concrete, steel and carbon fibre are not sustainable while harvesting a tree with a stone axe is sustainable if practised at a rate that permits regrow under local ecological conditions.
Note: I used a pseudo sustainable electric chainsaw rather than a stone axe to dissect this manuka tree. It will be replaced by a five finger (Pseudopanax arboreus), already growing up out of the decaying stump.August 19, 2018
I first came across this novel concept when I was a kid and friends of my parents had one. Seems like a pretty common sense idea so I've been on the look out for something like this for years. Finally I got the chance to purchase this stainless steel beauty. On the initial test firing we easily got the temperature up to 350 centigrade and it hovers nicely round 200 with the vents closed and the fire idling.July 17, 2017
Energy efficiency with hot water
Currently most of out hot water heating is done by electricity although we are are working on a number of strategies to reduce this component. One part of the approach is to keep the thermostat set so that the water is just hot enough.
I was having a conversation with someone about energy efficiency and hot water heating and what was the best temperature setting for the hot water cylinder.
The friend was operating under the incorrect assumption that it was better to have the cylinder as hot as possible so that when water was taken out, for a shower say, there was less cold water entering that required heating. There is a certain surface logic to this but it seemed to me that it doesn't matter what temperature the water is, when you have a shower or do the dishes you are extracting the same amount of energy (in the form of hot water) from the tank and so the energy needing to be replaced is the same.
The issue with keeping water extra hot then, is more to do with the extra energy that is required to maintain a greater temperature differential between the temperature inside and outside the hot water tank.
According to one website:
"The ideal setting is 60°C. It is important that the water in the cylinder is this hot to kill bacteria such as legionella but higher temperature settings only increase your power bill."June 17, 2011