Dear Oven builders, mud teachers, bakers, and eaters:
I would like to talk to you about some of the claims being published about the efficiency of earthen ovens.
I think we need to be clear that any masonry oven, whether it's made of unfired earth or fired brick, is not, by definition, a "fuel efficient appliance" – especially if it isn't insulated.
There are more and less efficient ways to work with an oven, and some of them make quite good use of the wood burnt in them, but in my experience, those ways don't apply to people who just want to cook a few pizzas, or a few loaves of bread, or perhaps a holiday turkey. That kind of use requires the burning of many pounds of fuel to cook just a few pounds of bread or meat. I don't think we can call that "fuel efficient."
There are different kinds of efficiency besides fuel efficiency, and those are, I think, equally important. "Efficiency" itself means "what comes of our making," and goes far beyond pounds of food cooked for pounds of fuel burnt. There is also the work of making family and community, which can benefit greatly from the kind of communal hearth provided by an oven. There is the work of building relationships with each other and the earth, which can benefit greatly from working together with strangers to build something beautiful and useful. Ovens can be wonderful even when they go unfired: simple and magical to build, lovely to look at, and beautiful for how they bring people together. But like every thing human — like every thing living — life comes at the cost of life — and in order to actually cook in your oven, the cost is the life of trees that we cut and burn as firewood.
I suspect that most of the ovens built in the US don't get used more than a few times a year, and if they bring people together for a day or even just a few hours, then perhaps the exchange of life for life is fair. If they are well insulated and fired with small dry sticks, the exchange is even better (good insulation under the hearth and over the dome can increase retention of useful baking temps from just a few hours to 12 or more).
But when we teach people to build ovens, or if we build ovens for clients, I think it's very important to be very clear that the simple /fuel efficiency/ of an oven can be anything from terrible (a few pizzas) to OK (pizzas, flatbread, loaf bread, meat, casseroles, lasagna, soup, pies, stew, cookies, warmed milk for yogurt, dried food, and dry wood for the next firing). In America, we are rich enough in fuel that we don't pay that close attention to how many trees we cut to cook our food — but that is not so in many other countries. So a claim of "efficiency" in America or on the web may carry the wrong message to a country where trees are scarce, and fuel is in short supply.
If you're interested, I'm happy for a chance to continue this discussion, either here on the blog site, through the comment option, or directly (contact me at handprintpress.com, or by snail mail at POB 576, Blodgett OR 97326).