The Case of the Missing Energy Model

Energy modeling, performance modeling, energy performance simulation – whatever you call it, it is becoming an increasingly important and increasingly easy and affordable process for early stage design. This article in Architect explores reasons it isn’t being used widely and the successes where it has been used.

Posted on: May 31, 2016

The Case of the Missing Energy Model

Building performance is increasing in priority, and the tools to predict it are becoming more accessible. So why isn't energy modeling used in every project?

Dave ChanceBrock Environmental Center, in Virginia Beach, Va., designed by SmithGroupJJR.

Carefully sited on an expansive parcel of land along the Chesapeake Bay, the Brock Environmental Center experiences the good and the bad of Virginia Beach, Va., weather—mild temperatures year-round, but clingy, perpetually high humidity. Yet the insulating value of the metal roof system topping the 10,000-square-foot structure is more akin to that of a building in the Northeast: R-50.

This design decision, says SmithGroupJJR vice president Greg Mella, FAIA, was determined through energy modeling, or performance modeling, as he calls it. “If we didn’t model, we would have used rule-of-thumb, and we never would have gone as high as we did,” the Washington, D.C.–based architect says. Completed in late 2014, the Brock Center was certified this month as a Living Building by the International Living Future Institute, one of about only 11 projects to date to achieve that recognition.

SmithGroupJJRAn evaluation of the effect of Brock Environmental Center's building orientation on predicted energy use intensity.

Environmental Center

Architects with high-performance projects—and, increasingly, the energy models and post-occupancy data to back their claims—fill speaker rosters at design conferences and events across the country. And the architect-centric audiences seem to extol these achievements. But step outside the trade show circuit, and the number of firms that routinely model their projects is surprisingly low.

The 2014 AIA Firm Survey found that 12 percent of architecture firms used energy modeling software for 2013 projects, with 61 percent of firms reporting no immediate plans to purchase software. Even within the portfolios of AIA 2030 Commitment signatories—a self-selected group of firms that have pledged to design projects with incrementally lower predicted energy use intensities (pEUIs), to the point of carbon neutrality by 2030—only 44 percent of projects are modeled in the conceptual or schematic design phase, according to the AIA 2030 Commitment 2014 Progress Report released last October. The percentage increases to 55 percent by design development and construction documents.

Kim Shinn, a Nashville-based principal at TLC Engineering for Architecture, estimates that his office is asked to conduct energy models for one of out every five projects. And of the design firms he works with, about 1 in 10 requests energy modeling services.

The benefits of energy modeling seem clear. The AIA 2030 report, for instance, finds that of modeled projects, 26 percent are on track to meet the commitment’s 2005–14 goal of reducing pEUI by 60 percent as compared to a baseline project, while an additional 21 percent come “close,” with estimated reductions of 50 to 59 percent. Of projects that were not modeled, only 21 percent managed to reduce pEUI by 40 to 49 percent, while the remainder fell below.

AIA 2030 Commitment 2014 Progress ReportPercent improvement in predicted energy use intensity based on whether the projects utilized energy modeling.

Generally speaking, architects want to design buildings that “touch the Earth as gently as possible,” says John Bacus, the director of product for Sunnyvale, Calif.–based technology company Trimble. And it’s commonly known that the early phases of design—conceptual and schematic—allow for the most meaningful improvements in building performance. So why isn’t energy modeling integrated early on for every project?

The primary reasons include cost and its frequent accomplice, time. Other reasons include disinterest by architects and clients as well as what An Architect’s Guide to Integrating Energy Modeling (AIA, 2011) calls “common misunderstandings,” such as the notion that only big firms and big projects can afford the staff and resources to conduct energy models. All of these arguments were similarly leveled against BIM, Mella says. But, he adds, the underlying reason often goes beyond money.

TLC Engineering for ArchitectureSolar study of Georgia Tech's Engineered Biosystems Building, conducted using Integrated Environmental Solutions' Virtual Environment (IES VE) software.

Cost Concerns Let’s start with money. Building owners with mid- to long-term interests in their projects would likely want to lower their operating expenditures, Mella says, “but few understand how design can impact performance.” Shinn notes that many architects are in the same boat: “Does $10,000 spent on energy modeling services yield $100,000 worth of energy savings over the course of the project? I would say that without question it does, but most architects don’t feel comfortable enough making that argument, mostly because they don’t have the experience.”

As more institutions request performance verification for their projects, architects may soon need to submit preliminary energy models along with their proposals. Though designers may fret about racking up a consultant’s bill before securing the commission, Shinn says his firm, for one, would likely “treat it as a marketing expense and probably wouldn’t charge the architect for those services until they got the job.” Energy modeling can also be conducted by in-house engineers and energy specialists, as well as design practitioners who have embraced building science, such as the sustainable design team that Mella leads at SmithGroupJJR.

If energy modeling isn’t conducted in the early stages of design, it’ll likely happen during code review. As jurisdictions adopt more stringent energy codes—including ASHRAE 90.1-2010 or 90.1-2013, the International Energy Conservation Code, and California Energy Commission’s Title 24—more projects will step off the prescriptive path by, for example, exceeding the maximum window-to-wall ratio of 20 to 40 percent (hello, glass towers). Design teams must then demonstrate that their projects can meet or surpass the prescriptive path’s requirements through performance modeling.

If architects learn that their projects fail to comply a mere stamp away from going to bid, it will be a messy and costly endeavor to fix. But if teams have been regularly energy modeling from the project’s start, Shinn says, “you can come up with solutions that are less expensive in first cost than if you follow the code's prescriptive path.”

Take, for example, the case of a hospital in the Southeast, Shinn says. This 24/7 high-energy-load building type has many particular requirements, including frequent air changes and backup energy systems to power a bevy of medical equipment. Insulating the building envelope per the prescriptive building code requirements could over-insulate the project, trapping too much of the residual heat from internal sources, such as lights, occupants, and machinery, and thus needlessly triggering the air-conditioning. Through energy modeling, Shinn says, a team can show that the hospital could meet the code’s performance requirements with less insulation, thus saving money on time and material.

Software Woes

As recently as five years ago, the complexity of modeling software was enough to discourage, frustrate, and befuddle even the most well-intentioned of architects. The programs’ onerous user interfaces—essentially, a series of spreadsheets and endless required entry fields—offered little insight on how design relates to performance. That’s not necessarily a criticism of the software. “Modeling the energy use of buildings is a complex multivariate problem,” Bacus says. “Tools like EnergyPlus are capable of doing that, but intense to configure and wildly complex to use.”

Developers have now eased the learning curve by integrating the powerful engines of established energy modeling software with designer-friendly interfaces, graphical outputs, and near-real-time evaluation. They have also simplified the input process so architects don’t necessarily need to know the HVAC equipment or lighting systems that will be installed, enabling one to run a preliminary model without requiring all of the minutiae. In fact, architects can now start an energy model as soon as a site is determined, Mella says. “I encourage teams to do a simple, generic-box energy model that sits on the site, and to run through a conceptual energy model. Then they’ll know what primary energy loads will be and use that to shape preliminary design ideas.”

Courtesy TrimbleSefaira interface Shinn cautions that while the output of energy models may be expressed quantitatively, architects would be better served using the results qualitatively, to compare options, particularly during the early design phases. “Energy models are windows into the physics of the building,” he says. “Without an understanding of the underlying science, an inexperienced user will not be able to tell if the information that is being returned is valid or the result of operator-input error." The good news, he continues, is that energy modeling and simulation tools are starting to take "user inexperience into account, and returning information in a way that it is easily understandable.”

“The software is now there,” Mella agrees. “The challenge is getting people to use it.”

With cost, legislation, and technology favoring the use of energy modeling in the early stages of design, all signs seem pointed toward "Go." So what’s left?

The Architect's Ego “The reason architects don’t use modeling is because they do not see design as an iterative or collaborative process,” Mella says. They think “modeling would somehow impede their creative process or compromise their vision.”

Dave ChanceBrock Environmental Center

In a profession that prides itself on creating collaborative spaces, inclusive workplaces, and chance-meeting spots, many architects still view design with a silo mentality. Though Mella acknowledges that design is easier when performance is not a consideration, he sees this attitude as “irresponsible and lazy, and I do believe that constraints enhance the ingenuity of a solution, rather than impede a solution.”

And energy models can become a substantive, objective-based tool in a designer’s arsenal to convince prospective clients to select their proposals. “When a designer can say, 'This solution is better because it provides more daylight, better energy performance, and lower energy costs,' then [the clients] can see this as a home run,” Mella says. Even if architects don’t pick the best-performing design, they will at least make an informed decision.

Bacus recalls that a colleague from Trimble-owned software developer Tekla recently said, “The future of BIM is to disappear and become simply the way we design buildings.” He pauses. “I would argue the same for energy modeling.” At some point, all of this will just become design.

The AIA estimates its 2015 progress report on the 2030 Commitment will be released later this summer. Note: This article has been updated since first publication to update the Brock Center's status as a certified Living Building by the International Living Future Institute.

Wanda Lau, LEED AP, covers technology for ARCHITECT and Architectural Lighting.