In the 1990s, Toyota Chairman Eiji Toyoda took every opportunity to preach about an impending crisis and to challenge his fellow executives. “Should we continue to build cars as we have been doing?” he would ask in his bid to promote a quantum shift in thinking, which would be crucial in the upcoming century. His questions eventually revolutionized the automobile industry with vehicles that deliver fuel economy twice that of their conventional counterparts while emitting half as much carbon dioxide. More important, it was the catalyst for restructuring the company’s design process.
Today, building industry leader Edward Mazria, FAIA, founder of Architecture 2030 (architecture2030.org), is challenging our industry do the same, and many firms are accepting his challenge. In response to global warming and rapidly diminishing supplies of fossil fuels, the 2030 Challenge is intended to put its adopters on the path to mainstream delivery of net-zero-energy buildings by the year 2030. Efforts to meet this challenge are causing some firms to reassess their current design process, and realize that the process must change before any mainstream product improvement can be realized.
A critical skill set that is needed in today’s design studio is the ability to perform quick energy-modeling simulations in a project’s schematic design phase. Those actively pursuing the 2030 Challenge have long known that the design process for truly high-performing buildings starts in the predesign and schematic design phases, yet there remains a lamentable absence of a systematic framework for employing this concept within most design studios.
To integrate such a framework within its design studios, at HKS we recently co-developed an educational program with TLC Engineering for Architecture. The result was a 90-minute game that is impacting firms and industry leaders who have participated in conference presentations of the game. One impact is the adoption of the concept by the Harvard Graduate School of Design.
The program, originally titled “A Night at the Energy Modeling Improv—Featuring the Wizard of SD,” is now referred to simply as the Wizard Game. The program was given this moniker because the presenters use the Schematic Design Wizard component of the eQuest software. The eQuest name is an acronym for Quick Energy Simulation Tool, and the SD Wizard component makes parametric modeling quick and easy. The game was presented at the 2010 GreenBuild Conference, and the presenters have subsequently fulfilled requests to repeat the program in nearly every climate zone in the U.S.
The game typically begins with an energy model of a 50,000-square-foot fictitious building set up to comply with the prescriptive requirements of the ASHRAE 2007 90.1 energy code. The presenters explain the base building in enough detail to give the participants an understanding of the base building design, its climate zone, and an understanding of where energy is being used within the building (lighting, cooling, heating, equipment loads, etc.).
The audience is then typically divided into two teams who are given an opportunity to compete against one another in a four-quarter game. It starts with each team selecting alternative building massings and orientations. Following consensus of the team members, the presenters perform live energy modeling of each respective team’s decisions and then quickly display the quantified reduction or increase in the predicted Energy Use Intensity (EUI) of their decisions. A graphic illustration of where the energy savings or increases were realized is also examined.
In the second quarter, each team is given a menu of building-envelope modifications to choose from. The five options include changes to roof insulation, wall insulation, window-to-wall ratio, glass types, and exterior sunshade devices. Following each team’s selection of two of the five options, energy-efficiency measures are modeled and the results of both teams are shared. The results are evaluated by the teams and explained by the presenters in detail before moving forward.
The presenters find that the teams at this stage of the game frequently select insulation improvements and glass-type changes. One of the lessons learned in this process is that that the energy code has already optimized the building insulation, and the benefits of adding additional insulation to a dominantly internal-load-based building are minimal and typically not effective in reducing the EUI. Another interesting observation is that teams are often attracted to one of the glass options simply because it states “Low E” in the title of the glass. This is despite the fact that provided performance data on that particular “Low E” glass, such as its solar heat gain Ccefficient (SHGC) or U-Value, is less desirable than the base building glass or other glass options. The modeling results of these selections reveal valuable lessons to the participants—particularly the importance of the proper glass selection for the given climate zone.
From another perspective, modeling can also rule out strategies that are ineffective or, in some cases, detrimental. For instance, the effectiveness of exterior sunshading devices is particularly dependent upon the climate, wall-to-glass ratio, and specific glass selection. Analyses have shown that in some climate zones, exterior sunshading devices can significantly reduce the EUI, but an equal number of cases have shown that in some areas they provide no energy reduction whatsoever. In some cases, particularly in cold climates, sun-shade devices can actually increase the building’s energy needs by cutting out too much of the desired winter heat gain.
In the third quarter, each team is presented with two internal-load energy-efficiency measures: daylight harvesting and a reduction in the lighting power density. Since there are only two options offered in this category, teams can select both of these internal options, or only one, plus one of the remaining building-envelope measures from the previous quarter. Because lighting roughly accounts for 30 percent of the building’s energy consumption profile, and also contributes significantly to the energy-consumption profile of the cooling system, the modeling results quantify the tremendous effectiveness that internal load-reduction strategies have on building design. Teams who select glazing with a moderate visible light transmittance (T-Vis) and daylight-harvesting systems that turn off artificial lighting when there is adequate daylight find that the combination is essential for high-performance buildings—particularly in warm climate zones.
By the end of the third quarter, each team has witnessed the effectiveness of both teams’ various strategies and is given the opportunity in the fourth quarter to revise all the decisions of the previous three quarters—massing, orientation, building-envelope measures, and internal-load strategies. Once each team has reached consensus on its design decisions, the results are modeled for the final time to calculate the reduced EUI and percent reduction in annual energy consumption from the baseline design. An energized dialogue among the team members is not uncommon as they debate which variants will yield the best results. Winning teams typically are able to achieve a 20 to 25 percent reduction in energy compared to the baseline ASHRAE 2007 model. This significant level of energy reduction is achieved without modifying the mechanical systems. The only item quantified with respect to the mechanical system is the reduction in the cooling tonnage that results from the passive-design decisions.
Energy modeling, once considered a tool of the mechanical engineer, is quickly becoming a necessity for the architect, especially for projects that are not fortunate enough to have a complete design team on board from the start. The modeling process provides a level of scientific rigor and quantitative data that is particularly helpful in communicating the logic behind design concepts that were previously difficult to justify. Its integration into the early phases of architectural design is critical to the design process, especially for firms aiming for the 2030 Challenge energy-reduction targets. A 20 percent or greater reduction in energy intensity, strictly through passive strategies, is significant. It places the project on a path to achieve extraordinarily low energy intensities while effectively reducing the size of the mechanical systems, and, more important, the cost of those systems. Such savings can be applied to highly efficient HVAC systems bringing the project within reach of the aggressive targets of the 2030 Challenge.
Kirk Teske, AIA, is principal and chief sustainability officer at HKS in Dallas, Texas. Hksinc.com.
