Net ZEB Case Studies - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 358

behavior - something that is fundamental for passive solar performance
assessment. Also, its lowest reporting frequency for output is monthly,
meaning that hourly comfort metrics, which are fundamental to informed
passive solar design, are unavailable.
Regardless of HOT2000's limitations, it was useful in estimating annual
performance - an essential element of predicting the net energy
consumption (or production) of the house in a standardized way. One of
the common methods used for deciding on key elements of ÉcoTerra design
was parametric analysis. For example, Figure 7.10 shows results that were
presented at the design charrette to support the decision to not
“super-insulate” the house. It clearly indicates that increasing wall
insulation from RSI-8 to 10 only has about half the impact of increasing it
from RSI-6 to 8. The vertical scale of the graph shows fairly marginal gains,
indicating that other approaches to reducing net energy consumption (e.g.,
higher efficiency PV) may become more economical.
Fig. 7.10 Results of parametric analysis that was used to decide on the
optimal insulation level in the walls
Tosupplementthis,thedesignteamusedcustomizedsoftwareprogrammed
in MathCAD (Chen, Athienitis, and Galal, 2010a; Chen, Galal, and
Athienitis, 2010b). The custom software uses an explicit finite difference
methodforspatialandtemporaldiscretization,sothatshorttimestepscould
be used and the benefit of thermal mass could be accurately assessed (see