Net ZEB Design Processes and Tools - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 232

commonly used in design practice. Performing parametric analysis
manually can be a time consuming process because multiple
simulations, input files, and results must be maintained. Similarly, few
tools provide built-in optimization features. Currently, most
optimization studies are performed using an external optimization
engine (e.g., GenOpt (Wetter, 2001)) to drive the BPS engine. This
requires knowledge of optimization, programming, and file
management and structures. Ideally, future Net ZEB tools will provide
greater support for optimization and interpretation of results.
- Knowledgebase and database: Building modelers must usually adhere
to at least one building code or standard (e.g., LEED (CaGBC, 2011),
ASHRAE Standard 90.1 (ASHRAE, 2010a), and local building energy
codes). Ideally, tools should have the compliance details for these
standards and facilitate entry of code-minimum building specifications.
- Useful graphical feedback: BPS tools tend to provide vast amounts of
data (e.g., extensive spreadsheets or automated reports) that can
overwhelm designers. Continued development in this area to provide
useful visual feedback about design performance would help facilitate
the Net ZEB design process. Several methods for graphical feedback,
including multidimensional parametric analysis and Sankey diagrams,
were suggested earlier.
4.4 Conclusion
This chapter has provided detailed discussions of two aspects of
incorporating building performance simulation and other tools into the
design process. The first focused on Net ZEB design practice and the
appropriate design stages for introducing different design features and
tools. The main conclusions drawn from that section are that emphasis
should be placed on establishing major decisions that affect energy
performance early in design; even if simple tools are used. These include
major geometry (for daylighting, passive solar heating, natural ventilation,
renewable energy collection), thermal mass (for passive solar design and
night cooling), effective envelope properties (e.g., insulation value and
window-to-wall area ratio), and basic control strategies. The later design
stages are mainly reserved for minor refinements and detailing. However,
because of the ambitious nature of Net ZEBs, the design stages are not
rigidly defined and many iterations may be required to achieve all