Defined as the amount of heat to be supplied to a given material to change its temperature, heat capacity of heterogeneous objects (separate parts made of different materials) may be well-defined and can be computed by adding together the heat capacities of the individual parts.
The heat capacity may be well-defined even for heterogeneous objects, with separate parts made of different materials; such as an electric motor, a crucible with some metal, or a whole building. In many cases, the (isobaric) heat capacity of such objects can be computed by simply adding together the (isobaric) heat capacities of the individual parts. Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to a given mass of a material to produce a unit change in its temperature. 
