Net ZEB Design Processes and Tools - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 212

The appropriate choice of airflow analysis model is dependent on the design
stage, the geometry and technologies of the building, and the type of
questions being asked. Airflow network methods are normally suitable for
energy simulations, but heavy reliance on natural ventilation and
assessment of localized thermal comfort could benefit from CFD. Examples
of tools for airflow analysis include CONTAM (for analysis of contaminant
flow using airflow networks and 2D CFD), ESP-r (airflow network and 3D
CFD), DesignBuilder, and IES VE (both 2D and 3D CFD).
4.3.3.6 Occupant Comfort
Occupant comfort - thermal, visual, and acoustic - cannot be neglected
during building design. Traditionally, comfort and energy have been viewed
as opposing each other and that a high level of occupant comfort requires
more energy (for HVAC and lighting) to maintain. However, in recent years,
it has been recognized that providing comfort is essential to
high-performance building design. If a building fails to provide comfortable
conditions, as designed, then occupants will adapt themselves and/or their
environment to achieve comfort. In some cases these actions have adverse
effects on energy performance. For instance, the owners of the ÉcoTerra
house installed an electric resistance heater in the garage - a space that was
not intended to be heated because it was nominally designed to shelter a
car. The 5 kW electric resistance heater was installed to maintain comfort
conditions required for a workshop. The result was that the garage, in its
first year, used 29% as much electricity for space heating as the rest of the
house (Doiron, O'Brien, and Athienitis, 2011)! Clearly occupant behavior
cannot be perfectly predicted during design; however, attention to occupant
comfort is important for achieving net-zero energy.
Theoretical aspects of comfort are discussed in detail in Chapter 3 ; this
section focuses on the modeling aspects of comfort.
Thermal Comfort
Traditionally, air temperatures, and sometimes operative temperatures,
were used to determine whether a space was comfortable or not. The
operative temperature is normally estimated as the average of the mean
radiant temperature of a space and the air temperature, for spaces with
low air movement (<0.15 m/s). However, the steady-state heat exchange
between occupants and the indoor environment is complex and is
summarized in Section 3.2. All occupant-building heat exchange terms are