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Boris Doderer

Interesting article, especially the paradoxon of turning a low energy home into one of zero energy by firing two cubic metres of wood per year. So, burning wood does not create energy, or what? Why, then, burn it? The change of definitions by manufacturers in order to sell something is a consistent nuisance to every person who's halfways intelligent.


Sorry, I'm more than half intelligent, and I understand what they meant, because I've been following green technology for about 10 years. Low energy homes are called such due to their low demand on external energy supplied by the local electrical grid or gas/oil supply. Calling it zero energy simply means that all necessary energy used by the house is generated by the house, resulting in zero external energy used. This is especially true if the wood is cut from the property where the house sits. Don't complain about market speak until you understand industry speak.

Carlo (Belgium)

Halfway intelligent indeed, one or two cubic metres per year keeps a stable balance with the growth of wood on your property. Also, burning wood releases just as much co² as it has filtered during its life. So if every tree that is cut is replaced with a new one this indeed doesn't leave a footprint on the environment. If the tree wouldn't be cut to burn (and release co²) then it would eventually fall and rot, what on its own turn creates the exact same amount of co² gasses.
I wouldn't consider the sellers' statement a lie or commercial bla-bla.

Jon Raney

I am surprised to see no mention of the Rocket Mass heater in these articles. These heaters have nearly all the virtues of those you discuss and in addition can be owner built by nearly anyone using local materials (ordinarily cob or stone) and because of their unique "top feed" and "rocket" internal draft system they burn small stock very efficiently. The seminal text on these stoves is "The Rocket Mass Heater Book" by Ianto Evans. Check it out!

Arnold Reitsor

Yep.. Rocket mass heaters are not mentioned. My own view about the difference: It is not too different in essence: burning hot with enough air, accummulating heat in a mass. The difference I see is mostly shape wise and speed of flow - Rocket Mass Heater makes a faster and more turbulent air flow, thus burning marginally better, but requiring addition of fuel and more attention. The eventual presence of a viewing glass in a masonry stove decreases the burn temperature, making a less complete burn. Rocket Mass Heaters as built 'traditionally' have the advantage of being used as seats with more practical arrangement for daily use and butt warming; almost philosophically - heat people not the house. Regarding exhaust temperature, I have not seen any information on exit temperature from masonry stoves; but RMH's do release quite 'cool' gases. On the whole, I regard the requirement of less attention as a major advantage of masonry heaters, while the arrangement of 'furniture' elements in a RMH is nice. Also, the vertical extension of masonry heaters makes any convection less effective than from the low laid Rocket Mass Heater. I would say it's a tie :-) Worth a discussion.


You can easily use a masonry heater in an air-tight house (with controlled ventilation) by completely separating the air flow to the heater, in the burn chamber and up the chimney from the air in the house itself. I don't see this happening as easily with a RMH.

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