Evaluation

The final phase of the PBD process is evaluating performance results. Once the design team has worked through several iterations of performance, it will be in a position to compare the performance results with the initial goals that it and the client set. These results will directly impact design, whether through the selection of envelope system materials, mechanical systems, glazing, shading, or any number of other design decisions. Collaboration and communication are key elements to the evaluation portion of the PBD process because every decision made early in the process can significantly impact the likelihood of reaching defined goals and meeting client expectations.

Image courtesy of SketchUp

Collaboration includes not only integrating communication between different stakeholders but also access to information across various devices and applications.

Collaboration within the design process is important no matter what the project, but it is critical for high-performance building design. Moreover, the PBD approach can help address some of the common challenges to a collaborative design process, such as identifying integrated design strategies, managing tradeoffs, and explaining design decisions to clients, as well as helping the firm know what worked well and why.

In addition to being able to collaborate with each other through the design process, the design team must also be able to clearly communicate with the client about the proposed designs. This is particularly important with the iterative analysis that is part of a performance-based design process, where key parameters may change with the various iterations. The design team needs to be able to track—and justify—these changes, but it also needs to be able to explain them to the client. By using a PBD process, the design team can focus on the deliverable and the output, and can provide the client with clear design comparisons that highlight the tradeoffs for different design decisions. This process can take place from as early on as site evaluation and should continue through the construction phase.

Using modern software to enhance and enable the PBD process during the evaluation phase can also help with setting and achieving realistic client expectations. For instance, early in the design phase, PBD software can evaluate a smaller, discrete portion of the project to demonstrate how changing a single factor might impact the overall design. This process is easier to grapple with than tackling a much larger, more complex study of the building.

For example, a team designing a K-12 school might ask, “What is the right glazing strategy for our classrooms that will provide great daylighting but not significantly increase energy costs?” Then, by using PBD design software, the design team can quickly and easily do a tradeoff analysis looking specifically at daylight and energy for a prototypical classroom of the expected size, with the aim of creating a list of the most viable options. By presenting this list and the potential impact of these options to the client, it can demonstrate how incremental choices can impact the overall energy use, maintenance costs, health, safety, and welfare of occupants after construction is finished. This type of instant and collaborative analysis helps the design team to stay focused on the initial performance goals, and can better communicate to the client how and why the design team took the design direction that it did.

Benefits of PBD

There are many benefits associated with the PBD process that can create a positive ripple effect, which extends from the design team to the client to the occupant and the world at large. PBD can be applied to specific projects or as an overall design approach that could help define a firm’s capabilities. Increasingly, clients are requesting design that can address the more demanding energy requirements, and architects and firms need to be able to meet those needs. For the architecture firm, there are benefits from consistently delivering high-performance designs in the form of a positively differentiated profile and stronger competitive position.

Let’s take a look at how PBD can also benefit other stakeholders in the design process.

Occupant Experience and PBD Projects

A performance-based design approach to a project helps architects and builders deliver the best occupant experience they can, all while keeping capital and operational costs under control. The balance between occupant experience and cost comes down to architects being able to analyze performance quickly and accurately, and to do so in the very early phases of the design before committing to major design decisions.

Occupants of office buildings, schools, and hospitals can all benefit from quality daylight, well-thought-out views, and stable thermal comfort. These factors are all linked with optimal employee productivity—up to 18 percent higher—and with improved learning in schools. Data also shows that patients in hospitals have improved recovery rates because of the carefully designed daylight and thermal comfort elements. These results are possible through traditional design, but a PBD process ensures that these outcomes are delivered reliably, at lower cost, and that they are truly integrated into the overall design and aesthetic.

Beyond occupants, building owners and managers also benefit from high-performance buildings in several ways, depending on the building type. Multi-unit residential buildings, such as large condominium and rental apartments, tend to benefit from a higher asset value when the building is designed with high-performance standards as a goal. Price premiums can be up to 30 percent more than buildings designed with approaches that don’t consider performance early in the design process. Occupied rental unit rates can be up to 17 percent higher and occupancy rates up to 23 percent compared to conventional buildings. These numbers stem from occupant experience with daylighting, views, and thermal comfort paired with lower operating costs and lower replacement costs of the properly sized (usually smaller) HVAC systems.

Comfort

Occupant comfort is key in building design, regardless of the use, and should be set as one of the core goals for a project. With a PBD project, occupant comfort can be addressed through defined metrics for daylighting, glazing, shading, air quality, and thermal comfort, among other parameters. By including and analyzing these factors in the preliminary design process, architects can reduce unexpected occupant comfort problems once the building is completed.

Health, Safety, and Welfare

As with occupant comfort, health, safety, and welfare are all critical goals that need to be addressed at the very start of the design process. A PBD approach makes addressing these elements straightforward. The iterative process, especially when combined with an appropriately linked 3-D drawing and modeling system, can produce informed design choices that meet all code requirements for the health, safety, and welfare of the specific building type.