Net ZEB Design Processes and Tools - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 201

allowing zones to be multiplied by some integer such that only a single
zone or group of zones needs to be modeled.
The required resolution of the model geometry is dependent on the
phenomenon being studied, as summarized in Figure 4.16 . For determining
thermal loads resulting from heat transfer through the building envelope, a
simple model may suffice. Detailed HVAC simulation models should have
zones sized according to the HVAC control zones for the actual building.
This ensures different space loads - sensible and latent - can be met by
the proposed HVAC system under the expected thermal loads (e.g., solar,
occupants, equipment, and heat loss). Detailed daylight and acoustic
analysis are among the most demanding on zonal configuration because
most BPS tools typically require zone boundaries to represent interior
surfaces. In fact, grouping rooms into a single zone is likely to overpredict
daylight illuminance because fewer partitions between spaces causes better
daylight penetration. This is in contrast to thermal domain modeling where
it is normally acceptable to merge several rooms of similar air temperature
into a single zone.
Fig. 4.16 Model geometry resolution by building aspect
Ultimately, the limiting factor for zonal configuration may be dictated by
the most advanced aspect required (as per Figure 4.16 ). For energy analysis,
modeling every room as a zone should be avoided if possible (especially for
large buildings) because it is not only computationally expensive, but also
very time consuming to model and can create excessive volumes of output
data and difficulty for debugging models.
4.3.3.2 HVAC and Active Renewable Energy Systems
Heating, ventilation, and air conditioning equipment is usually responsible
for the majority of energy use in buildings - especially those that are in cold
or hot humid climates, actively conditioned, and sealed (i.e., not reliant on
natural ventilation).