Net ZEB Design Processes and Tools - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 228

Fig. 4.27 Two-dimensional sensitivity analysis for two parameters that
weakly interact: wall and ceiling insulation (left), and strongly interact:
window-to-wall area ratio and house orientation (right) (O'Brien,
Athienitis, and Kesik, 2011a)
4.3.4.6 Visualization
Providing a means to synthesize and visualize performance data is a key
role of building modelers - given that the intended audience is primarily
designers and other stakeholders. Care must be taken to provide enough
information to make meaningful decisions without overwhelming the
audience.
One strategy for representing energy flows in a building and ultimately
identifying the best strategies for achieving net-zero energy is through the
use of Sankey diagrams (Schmidt, 2008). As illustrated in Figure 4.28 ,
Sankey diagrams help identify the major energy sources and sinks within
a building. For instance, it shows the solar heat gains through and heat
losses from windows in each orientation. Thus, the net heat gain can be
determined. Furthermore, the Sankey diagram identifies any major
weaknesses (i.e., major sources of heat loss) in the envelope. Finally, energy
conversion processes (e.g., use of electricity for a heat pump to extract heat
from the environment) and feedback loops (e.g., use of a heat recovery
ventilator - not shown) can be visualized. The creation of Sankey diagrams
forces designers to ask the right questions about Net ZEB design, including
1. What are the major energy sinks in the design and how can they be
reduced?
2. If energy sinks cannot be reduced through conservation measures, how
can renewable energy sources be used to offset these sinks?