Energy cost was calculated considering for each fuel i the cost of the related stove j (CSj) spread on its lifespan (LSj), and the fuel cost, according to the share of required energy covered by that fuel. The fuel cost was estimated multiplying the unit cost of
the fuel (Cfi) for the total quantity of fuel needed. Fuel quantity was calculated considering the net calorific value of that specific fuel (NCVi) and the share of the yearly net energy need (ET) covered by that fuel (fi).