Why Energy Modeling is Art
Why Energy Modeling is Art
Originally published on the USGBC blog
Amir Rezaei-Bazkiaei, PhD, BPAC, LEED GA
When Edvard Munch was painting The Scream, he probably didn’t know that the piece would leave many art lovers in awe for years to come. I am not an art professional, but I believe that he was very excited at the moment of creation; and, he has portrayed his feelings the best way possible using his unique technique. You can’t say the piece is perfect because there is never a sense of perfection for an art piece, but it has a beauty that cannot be compared to any other painting. Fast forward to 21st century and now to building energy, I believe that the building energy modeling process requires great observation, passion, and attention to detail which is very similar to creating a painting. The fact that the modeler often looks like the guy in “The Scream” is not a coincidence. The model usually needs to be completed in a short period of time requiring skills that, if done masterfully, are on par with creating a painting in which only you as the artist know what is hidden in every corner and what it has to say. The following is a summary of my artistic approach to energy modeling.
Make sure your energy model does what you want and how you want it to be done.
You would not want to use watercolor technique if you are a master of oil painting. Similarly, you would not want to use a modeling platform that can’t perform the tasks you are interested in. Researching how different modeling tools account for the same phenomenon is the key to a successful energy modeling process and can save a tremendous amount of time on the project. Examples of design aspects that require due diligence to validate the accuracy of the energy model are:
• complicated water loop designs with several mixing points
• equipment and controls
• thermal mass studies
• airside and waterside heat recovery devices
• passive designs such as solar chimneys, natural ventilation, earth tubes, etc.
Most energy modeling platforms allow for workarounds if a particular design aspect is not readily available as an option in the software. However, many times these workarounds involve assumptions and simplifications. If you have to stick to your modeling tool, be aware that the level of simplifications may cost you the accuracy of your simulation, in which case you need to communicate your modeling approach to your colleagues/client for validation. This requires creative/artistic thinking on what techniques to use to tell the energy story of the building while not losing the credibility of the model.
Break down the success of your model and its inputs into measurable steps.
Think about your model as an art masterpiece. You would want to have different sections of the final picture, or at least a clear layout, in mind before you start. Depending on the type of modeling platform, you may need slightly different checkpoints, but the following are general checkpoints to either visually or numerically validate your building energy model.
• building surface dimensions
• assembly thermal properties
• internal gains and schedules
• zone airflow rates and serving equipment
• mechanical equipment specifications
• model run/troubleshoot
• results check for abnormal trends
Make reasonable assumptions and move on.
I find myself making most of the modeling assumptions on the occupant behavior. Despite attempts to quantify the impact of occupants on the building energy consumption, it’s almost impossible to capture the occupant behavior with great detail. A great example of this is choosing the right schedules for occupancy and internal loads. As an energy modeler, you are always simulating (or emulating) the reality of a building system. It is crucial to always keep in mind that no matter how closely you imitate the performance of the entire building system, there are always factors in the real world that are out of your control and will affect the energy performance of the building. In my opinion, the key to modeling assumptions is to document as much as possible, and also be aware that the building energy model is a dynamic creature that needs updating. Another reason energy modeling is art: you need to know about human behavior!
Choose the right metric to communicate your modeling results.
As much as the accuracy of the model is important, the final purpose of the energy model results will influence how you build the energy model and present the results. For example, if your goal is to model the thermal comfort or indoor air quality, the client is probably interested more in checking the hourly indoor air temperatures rather than the annual energy use intensities. Knowing whether the energy model will be utilized to calculate loads for equipment selection, to generate results to be used for a life cycle cost analysis, or to make very early massing/orientation decisions will also dictate how much detail is required for the energy model and what the right metrics for communicating the results are. Artists often imagine how their paintings will look before they begin working.
The more the merrier.
The more energy modeling tools you know how to use, the easier it gets to become a versatile energy modeler who people can depend on. It’s almost as if you can paint, sculpt, and create music at the same time, if needed. This contrasts with the natural tendency to be a “creature of habit”, since you need to push your boundaries to continuously learn new tools and workflows around them. It certainly isn’t an easy job to keep up with the new developments and modeling workflows for different tools but it is a rewarding experience to learn multiple tools.
Know the team you are working with and the impact your energy model may have on their tasks.
Every engineering team uses their energy modeling tools differently and for different purposes. Make sure you communicate the project goals with your teammates and determine whether they can be satisfied by an energy model. Here at MKK for example, we truly believe in the power of integrated sustainable design where energy modeling becomes a necessity to emulate how high-performance buildings’ perform. Having recently transitioned from a consulting firm to MKK where we design HVAC systems, I know the power of the energy modeling to inform system selections at early stages of design and strive to integrate energy modeling in the design process. Integrated design is all about becoming creative and poetic with buildings, and what better way than having a host of modeling tools at our disposal to do so.