White Papers

6 Copyright ©2013 Sefaira Ltd. PER FOR MANCE BASED DESIGN: CR E ATING HIGH - PER FOR MING CONCEPTS Iteratively Optimize Design Concepts As the design progresses, the design team needs to know what can be done to improve each design. Which strategies would be most effective at improving performance? What is the "best case" performance for a particular design? Can we find a package of strategies that can achieve the project's performance goals? Earlier we showed a "best case" comparison for three design options. Here we will take a look at the process we used to create the optimized Lens option. While the Lens was initially a middling performer, we hoped that the right combination of strategies could get this option to perform similarly to the top-performing Corner option. Our process looked like this: • Drill into energy use. The Lens is driven first by space cooling, and second by space heating. Cooling was driven primarily by solar gain through the glazing; heating, by conduction through the glazing and walls. • Find the best strategies. We tested a large number of strategies to see which were most effective. To reduce cooling, we tested shading devices, natural ventilation, and thermal mass. We used paramentric analysis to find optimal values (for instance, the type and length of shading devices). To reduce heating, we tested insulation, reductions in leakage, and improvements in glazing. • Explore combinations. Finally, we studied strategies in various combinations, to understand which strategies work well together. For instance, traditional "passive solar" design involves combining higher southern glazing ratios with thermal mass, shading, and glazing improvements. We also used combinations to find multiple paths toward the same goals: for instance, to reduce cooling we could Fig. 3. The preferred design option was not the top performer. How could we make it better?

• Cover