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5 Copyright ©2013 Sefaira Ltd. PER FOR MANCE BASED DESIGN: MAK ING THE MOST OF PR E- DESIGN Explore Adjusting the Design Brief The design brief and building program define the requirements for a design. Pre-design is the right time to look closely at these requirements to make sure they are correct, and to explore whether they are fixed or flexible. Assumptions about mechanical systems and thermal comfort requirements are par- ticularly important. Do all the spaces need to be heated and cooled? Can the comfort zone be extended in some spaces? Is it possible to eliminate one or more mechanical systems?—a move that could save capital cost as well as operational costs. Other relevant investigations at this stage can include: reducing area requirements, adjusting heating and cooling setpoints, and changing the amount of conditioned area. Performance analysis can show which adjustments could have the largest impact, and enables the design team to have an informed conversation with the client about the requirements and potential trade-offs. We used our simple box model from the previous step to investigate the potential for eliminating mechanical cooling systems entirely. Our initial results showed that a combination of shading, natural ventilation, thermal mass, and insulation could keep air temperatures within a comfortable range for the large majority of the year, and could keep temperatures below 28° C (82° F) for all occupied hours (Fig. 4). We can use this information to discuss the possibility of an expanded comfort zone with our client. It also reinforces the passive analysis from the previous step, highlighting the importance of key design strategies such as natural ventilation and shading. 0 1000 2000 3000 4000 5000 Occupied Hours Thermal Comfort (Occupied Hours) <18 18-20 20-22 22-24 24-26 26-28 >28 (°C) Temperature <64 64-68 68-72 72-75 75-79 79-82 >82 (°F) 7000 Thermal Comfort (Occupied Hours) Fig. 4. Projected air temperatures over the course of a year with passive strategies implemented. Pas- sive design alone can maintain comfortable conditions for the majority of occupied hours.