Tulikivi - Birth and Evolution
Perhaps one of the true origins of the "green" revolution, thermal mass fire places were originally designed to help conserve precious resources: in this case, firewood. The story goes that in 18th century Europe there was a shortage of firewood. The King of Sweden found two creative barons and told them, "Yo, this energy crisis is whack. Invent a stove that burns more efficently or we might go medieval on you." Being that the alternative involved the possiblity of death, the two barons did get creative and came up with a stove that captured heat from the escaping flue gases and radiated it into the room. The thermal mass heater was born: a huge improvement over the traditional fireplaces that sent most of the heat straight out the chimney. With the new technology, the amount of wood the traditional heater consumed in one day now lasted a week.
Not long after its conception the design found its way to Finland. The Finns started by constructing the heaters with a unique material known to them as soapstone. They also simplified the design with "contraflow" channels, replacing the complicated baffles in the original Swedish design. The improved design found its way back to Sweden and was widely adopted everywhere. The Tulikivis we know today are a modern version of those original thermal mass heaters.