Net ZEB Design Processes and Tools - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 163

phase - not in detail, but at least, with an estimated order of magnitude
depending on the expected internal loads. A well-designed building would
ideally store the solar and internal gains during the day and release it at
night. For moderate climates in summer conditions, one method to
determine the appropriate thickness of thermal mass is to ensure that the
thermal mass temperature increases by no more than 5 °C during the day,
assuming that this mass is regenerated during a night shift where operation
between 21 and 26 °C is allowed. The admittance approach described in
Chapter 2 may be used in the early stage of the design to decide mass
thickness. The amount of mass has important implications on structural
design since the structure must safely support the thermal mass.
In complex simulation tools, the design of exposed thermal mass requires
coupling of the thermal and air flow networks. This kind of simulation is
not possible in the early design phase due to the lack of available inputs
(e.g., optical properties and thermal capacitance of building material and
furniture, and specific location of windows). As a result, in the concept
design, building designers should keep in mind that thermal mass (e.g.,
exposed concrete, phase change materials or other) may need to be
incorporated in the design. Figure 4.2 presents an example of thermal mass
integration in a commercial building where the concrete columns and slabs
are exposed. Structural considerations need to be taken into account when
implementing thermal mass.