Issue link: https://read.uberflip.com/i/1153220
3 Copyright ©2013 Sefaira Ltd. PER FOR MANCE BASED DESIGN: E XECUTING THE VISION Optimize Passive Strategies In the previous Sustainable Design Brief, we showed how designers could find combinations of passive design strategies that could deliver breakthrough performance. With the basic building design now defined, the design team can begin to fine-tune these strategies. Advanced parametric analysis can be used to find optimal values for elements like shading, insulation levels, reflectance, and glazing properties. These properties can be used to inform wall sections, details, and specifica- tions, as well as providing inputs into BIM models. Sizing these strategies appropriately can improve a project's bottom line. For instance, finding the right length for shading devices can prevent the design team from over-sizing these devices—an error that would increase capital cost as well as operational cost. For our design, we used Sefaira's Response Curves to study the behavior of glazing solar heat gain coefficient (SHGC) or g-value, shading, and insulation levels. We found the following: • Shading: We were able to find an optimal shading specification for each facade: 2-ft (0.6m) horizontal shades on the south facade, and 1-ft (0.3m) vertical fins on the east and west facades. Using these parameters as a guide, we modeled a number of custom variations to find the most effective design that achieved both performance and aesthetic goals. • Glazing Solar Heat Gain: When combined with shading, we found that standard double-glazing was optimal for our building. This prevented us from accidentally making the glazing "too good"—in this case, additional reflectivity would actually increase total energy use by keeping out beneficial solar gain in winter months. • Wall R-Value (U-Factor): Insulation values exhibited diminishing returns. We were able to use these results, in combination with cost estimates, to determine the most appropriate insulation levels for our project so we could achieve the best performance for the least cost. Because each of these factors is interrelated, changes in one part of the design are likely to have impacts elsewhere. Therefore, we will continue to perform this type of analysis as the design continues to evolve. Fig. 1. Parametric analysis can be used to fine- tune sustainable strategies. SHADING SOLAR HEAT GAIN COEFFICIENT (OR "G-VALUE") WALL INSULATION