Practicing ArchitecturePracticing Architecture
Sustainable AIA: 2031–Why Energy Models Don’t Predict Actual Energy Use
By William J. Worthen, AIA, Director and Resource Architect for Sustainability
Have you ever been denied a building permit based on your project’s energy performance?
Very likely, the answer is “not yet.” Documenting energy performance metrics to show code compliance with ASHRAE’s 90.1-2010 or California’s Title 24, Part 6-2008 just isn’t something many architects include in their typical scope of work. But meeting code requirements that include performance-based energy requirements–as part of the building code–will force a change in the status quo. Even if you have designed LEED Platinum-certified buildings, to date very few architects really appreciate what MEP engineers and energy modelers do when they walk behind the energy modeling curtain and return after much time and effort with “the number” that determines whether or not the design is in compliance with the applicable energy code.
Why should architects want to change the design process to more substantively incorporate energy models? After all, aren’t architects trained in the fundamentals of building sciences as part of our education and licensure? Personally, I have a Bachelor’s of Science in Building Science, earned as part of an accredited architecture degree. So, why do architects need energy models to validate our ability to design high performance, energy optimized buildings? Because the codes are about to require it.
Are we ready for simulation tools to provide a constructive critique of our ability to do “good” design and high energy performance? I would argue we need it more than ever. After all, as buildings increase in design complexity, their energy use also becomes more complex and may become even more counterintuitive, making the most cost effective, energy efficient building strategies much harder to understand and quantify in terms of best value for our clients. If we take the time to embrace this emerging field, we can use energy models for much more than just code compliance. Providing context and cost/benefit data allow us to make informed, value-based decisions so we can really know, for example, if automated shade controls would have greater potential to improve the overall performance than external shading devices.
If this is where high performance building codes are moving related to energy models, why aren’t today’s energy models doing a very good job of predicting a building’s actual energy use? The simplest answer to this complex question is that today’s modeling tools are not intended to provide any higher degree of predictive certainty for actual utility bills than the miles-per-gallon ratings displayed on the window sticker of your last new car will predict real life mileage. Hopefully, that number influenced your selection of the car. But when you drive off the dealer’s lot, most people don’t drive their cars exactly the same way the mileage testing was designed.
Despite all the simulations, concept testing, and 3D modeling that the automotive industry uses (and in some ways, it races ahead of the building industry’s predicative capacity), it’s simply not possible to design a car in a lab and then predict exactly what city and highway mileage you will get when you start driving. Understanding this concept as it relates to whole-building performance and energy models (and communicating this to our clients) will be a key factor in the success of high-performance building codes. This is also the key to architects embracing a new generation of energy modeling software currently in development at national energy labs. The AIA is involved in the development of several of these new, rather user-friendly tools, which will be tailored to the specific professional expertise of architects.
An energy modeling summit
Last week I attended the Energy Modeling Innovation Summit hosted by the Rocky Mountain Institute (RMI) in Boulder, Colo. With a 125-page intensely technical pre-read tract in hand, I was not sure what to expect. Certainly, it was a valuable experience. Today, the fragmented field of building energy modeling suffers from a lack of standardized inputs, the need for new and better modeling algorithms, and wide variety of other challenges. These tools are often ad hoc and arbitrary in their application and the RMI summit was an important step in the right direction towards closing these gaps. All this is about to change with CALGreen and the IGCC, and the many local green building ordinances already in place across the United States.
If you and your firm want to get ahead of the curve, consider taking the time to identify and build ongoing relations with design professionals with specialized energy modeling expertise. Do not assume your MEP engineers have the needed expertise (or proper scope) to use energy modeling as part of the iterative design process. As a sign of hope for the future on this subject, I was pleasantly surprised to learn that more than a few of the experienced energy modelers who attended the RMI summit were architecturally trained before finding an affinity for energy modeling. Hopefully, some young architects will also choose to explore this new permutation of design and practice. It’s a field that is about to grow rapidly in the coming years.
The last thing any architect wants after a project receives its building permit is to realize the design does not meet new high performance building codes, only the building codes we all have already spent careers getting to know. Being sent back to the drawing board by the code official at this late stage in the game can set off chain reactions that might just sink a project forever. If the code violation points to the overall design and aesthetic of the façade, changing it might require going back to the local planning review board. If they don’t like the amended, code-compliant design, this surprise round of public input can lead to some awkward conversations with clients. No matter what the building code says, our clients assume we know how to design to meet it.
The AIA is working to help all members avoid this scenario as much as possible. This includes working across the Institute and with our industry partners to prepare tools and resources for the game changer that is high performance building codes. The subject of energy modeling is of such importance for architects to understand that it’s a major focus of sustainable education programs and my work at the AIA in 2011.
In the months ahead
If you would like to participate in the dialog about what energy modeling tools architects need, ASHRAE is hosting a three-day meeting on the subject April 4-6 called Energy Modeling: Tools for Designing High Performance Buildings. I will be co-keynoting this event with the president of ASHRAE, Lynn G. Bellenger, and I am encouraging interested architects to attend.
The AIA has formed an energy modeling working group that is actively developing a practitioner’s guide on how to use energy modeling in the design process. An AIA document will provide an overview of all available energy modeling tools and engines, their interoperability with CAD and 3D software, questions you should ask your energy modeler, and other information written with architects’ expertise and technical understanding in mind. The guide will be published in December 2011, and a draft document for any AIA member to review and comment on will be available late this summer on the AIA Sustainability Web page. Look for updates about the working group’s progress and the review schedule in the coming months, as well as information about sessions at the AIA Convention in May. There, we will be presenting the concept draft for this guide as part of the convention session “Energy Modeling: What You Need to Know.” All members are also invited to an AIA Sustainability meeting at the convention for a broader overview of the AIA’s work on green codes education tools and resources in development, including a series of 60-minute educational videos on high performance design issues. The first one will focus on energy modeling.
Please share your thoughts on an integrated design approach to energy modeling at email@example.com.