A team of students at Waseda University in Japan have constructed a prototype for a house that can be heated by composting straw. They dubbed the dwelling the “Recipe for Life” house. Using the heat generating composting process for the purpose of heating a dwelling is not a new idea, but it is definitely one that should be explored further, and perhaps brought closer to the public. The Recipe for Life prototype house is certainly an interesting proposition in that regard.
The interior walls of the house are made of acrylic boxes, which are packed with the straw for composting. The exterior walls are also covered by straw, over which wooden panels, with handles for easier removal are placed. The prototype the students built uses a traditional composting technique called “bokashi” (which translates as “fermented organic matter”) that is quite simple to achieve. As it ferments, the straw inside the walls releases about 30 degree Celsius (86 degree Fahrenheit) of heat for a period of 4 weeks. The fermentation process of straw is considered low-odor, though the nature of the process means that there is at least some odor present. The design also makes it possible to cool the home in the hotter months of the year.
In the summer, the acrylic boxes that make up the walls of the house are packed with straw. This straw then dries inside the large, see-through boxes that are stacked along the interior walls of the house. During this process, moisture is released, which cools the interior of the house. In the winter, on the other hand, the straw ferments inside the walls, giving off lots of heat as a byproduct.
For this house to function properly, the straw would have to be exchange a few times per year. Also, the fermentation process only produces heat once it has reached a certain stage in its organic breakdown process. This means that the heating of a house utilizing this system would have to be interrupted when the time to replace the straw comes. This is certainly one of the drawbacks of this method. The design does, however, provide household heating and cooling in a totally natural, and organic fashion and is definitely worth exploring further in an effort to find more practical applications.