1. The first case study is located in North-West Pacific, in the Cold Subarctic climate; as already explained in the previous chapter, in these kinds of climates the thermal mass of the building elements is essential in passive solar spaces designed to store heat. So far, the rules for the design of this passive technology have been developed in the dry, sunny American South-West; since this latter climate is quite different from the Cold Subarctic one, the purpose of CIT is to employ a series of field-validated Pacific North-West sunspace models to quantify limitations of conventional thermal mass design in the region and to reveal more suitable parameters with respect to the sizing and ground configuration of floor-based thermal mass.