"Ask a Modeler" Column Archive

9-20-2021: Ask a Modeler: How Do You Explain Complicated Physics Principles to Architecture Students?

Heba Hassan, Dr. Eng., Assistant Professor at Beni Suef University, replies: "Dear Teacher, Let’s take up this challenge in steps. First of all, we should know the background education of the student and the level of their knowledge about the physics principles. If his education is in a different field, such as biology or medicine, more effort is required to simplify such principles. If the student’s previous experience is in a related field, they will understand more quickly and easily..."

7-20-2021: Ask a Modeler: When Should I use Future Weather in Building Energy Modeling, and What Climate Change Model Should I Use?

Melissa Allen-Dumas, PhD, Research Scientist at Oak Ridge National Laboratory, replies: "Dear Forecasting, It’s exciting to me to know that there are forward-thinking building energy modelers out there that care about designing buildings for future climate. Climate change has everything to do with Title 24’s standards for “energy conservation, green design, construction and maintenance, fire and life safety and accessibility,” as climate affects the yearly profile of meteorological parameters that are input to the building energy models that assess the level of a building’s or a neighborhood’s ability to meet these requirements..."

6-15-2021: Ask a Modeler: What is the Best Approach to Simulating Geometrically Complex Buildings?

Adam Ozinsky, Environmental Designer at Atelier Ten, replies: "Dear Not Always Right-Angled, A medium-famous architect once commented: if it's not a right angle it’s a wrong angle. As square as that approach may seem, it did make modelling slightly more straightforward than with some of the geometrically complex creations we see in vogue now. For better or for worse, complexity has made our days as building performance modellers more challenging. And our nights longer..."

5-18-2021: Ask a Modeler: How Can We Maintain Better Compatibility Between Models, or Do We Need To?

Conor Rielly, Building Energy Analyst at CannonDesign, replies: "Dear Consistency, We have been down this path before, especially if you have an involved mechanical or electrical engineer. It is way into a construction document or permit set development cycle, and everyone is anxious to get the documents out the door and know what the energy model is predicting for design EUI or LEED points..."

4-20-2021: How Can Energy Modeling be Made More Scalable and More Manageable for Retrofit Projects?

Zoltan Nagy, PhD, Assistant Professor at The University of Texas at Austin, replies: "Dear Big Apple, First off, let me start by saying that I think that LL97 is a step in the right direction, as buildings are responsible for 30-40% of the greenhouse gas emissions mainly due to the energy needed for heating and cooling. Starting 2024, LL97 places carbon emission limits on most buildings across NYC..."

2-16-2021: How do You Effectively Communicate with Architects and Engineers Who May be Resistant to Giving Up Control?

Bill Sommer, Project Manager at Sain Engineering Associates, replies: "Dear Teacher, In the Northwest, I’d probably use a craft beer. California? Wine, of course. Here in the Southeast, bourbon does the trick. You are part of a team, so you need to be a team player. Teamwork is a mental discipline. Understand the roles, responsibilities, and most importantly, the influences driving your teammates decision making..."

12-15-2020: How can I Get as Much Use as Possible Out of One Model?

Demian Vonder Kuhlen, Senior Associate, Building Performance Team Leader at Guttmann & Blaevoet, replies: "Dear Recycled, The road to energy model reuse is fraught with potholes. The zen of model recycling nirvana is close at hand, but your mileage may vary depending on your software, your experience, the scope of work, and the level of model detail needed to produce the requested results..."

11-17-2020: What Possibilities are Unlocked by Doing Energy and Environmental Simulation on the Cloud?

Mostapha Sadeghipour Roudsari, Co-founder of Ladybug Tools LLC, replies: "Dear Head in the Clouds, Simulation on the cloud introduces two major opportunities: The first is scalability, which means that simulations can be run much faster, and the second is that simulation becomes much more accessible, which opens the gateway to better collaboration..."

10-20-2020: Are There Strategies to Save Cost and Energy by Changing the way HVAC Load is Calculated?

Volkan Doda, Associate Environmental Designer at Atelier Ten, replies: "Dear Right Size, Rejoice, as gone are the days of boasting about the biggest kit in town. Now is the time of the kit that is just the right size to do the right job right. It’s obvious: good engineering strives for a working solution with ever higher efficiency by designing out waste. Coincidentally, not paying for waste also tends to make things cheaper. Great, but what’s the right size then, I hear you ask, and this is indeed where things get murky..."

09-15-2020: Should the Modeling Community Focus More on Existing Buildings to Battle Climate Change?





Alex Nutkiewicz, M.S., PhD Candidate at the Stanford Urban Informatics Lab, replies: "As many readers might agree, buildings are a critical component of a sustainable, low-carbon future. In 2019, 28% of all primary energy consumption (and subsequent carbon emissions) in the United States came from our buildings (International Energy Agency). And while there are emerging policies that emphasize the importance of energy efficiency in newly constructed buildings (California Public Utilities Commission)..."

08-19-2020: What are Some New or Creative Sources of Hard-to-Get Data?

Rhys Goldstein, Principal Research Scientist at Autodesk Research, replies: "Dear Playing, I’m happy to suggest a few “creative” sources of data for you to play with. You’ll have to judge whether they’re appropriate for your work! Let’s start with occupancy schedules. Suppose we want to derive them from the behavioral patterns that occur in an existing building. Our first instinct may be to explore the various technological solutions at our disposal... Sometimes the simplest solutions are the best..."

07-21-2020: Are There Any Aspects of Buildings That Current Simulation Tools Do Not or Cannot Address?

David Goldwasser, Software Developer and Researcher at NREL - Buildings and Thermal Sciences Center, replies: "Dear Testing, The short answers are yes and yes, which is why whole building simulation engines and modeling tools are continually evolving. When developers consider adding a new functionality, they perform a balancing act of the impact of a building characteristic or element on consumption, equipment sizing, comfort, and safety against the cost and complexity of implementing, modeling, and simulating that building characteristic or element..."

06-16-2020: How Well do Building Simulation Programs Model Thermal Bridging?

Som S. Shrestha, R&D Staff Scientist at Oak Ridge National Laboratory, replies: "Dear Learning, Building envelopes are non-homogeneous, so heat transfer through a building envelope is not one dimensional due to thermal bridging. However, thermal bridges cannot be explicitly modeled in most whole-building simulation tools, including EnergyPlus. Therefore, modelers need to somehow account for the impact of thermal bridging in their building models..."

05-19-2020: When is the Earliest in the Design Process That Useful Performance Simulation is Possible?

Eric Flower, Software Account Executive at Willdan, replies: "Dear Early Bird, Where did the time go? Design evolves at such a fast pace that decisions must often be made based on partial knowledge. Because the design process is dynamic, every stage of the process presents its own unique opportunities for 'early moments'..."

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04-21-2020: What Questions Do You Ask When Doing Sanity Checks on a Model?

David Eldridge, Energy Efficiency Ninja at Grumman/Butkus Associates, replies: "Dear Sanity, Where did you go? Sanity seems to be out the window these days. But if you feel like you are losing it while working from home, at least your modeling results don’t have to be a contributor..."

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03-30-2020: What is the Biggest Misconception Designers Have About Energy Modeling?

Sara Motamedi, Senior Building Performance Analyst at Interface Engineering, replies: "Energy modeling provides us an insight about the importance of design decisions on total energy consumption. On one hand, I’ve seen architects who are eagerly waiting for the energy modeling results..."

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02-18-2020: How is the BEM Industry Changing to Meet the Challenge of Mandatory Energy Codes?

Krishnan Gowri, Building Performance Practice Lead at Intertek, replies: "Challenge comes along with the tremendous growth we are experiencing to meet the simulation and modeling needs of the design community..."

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11-19-2019: What is the Future of Energy Modeling Going to Look Like for the Industry?

Michael Wetter, Staff Scientist at Lawrence Berkeley National Laboratory, replies: "The future of energy modeling will be similar to the present of energy modeling—EnergyPlus is not going away..."

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10-16-2019: What are Some Alternative Careers that use Building Energy Modeling Skills?

Stephanie Egger, Product Manager at AMS, replies: "Speaking as a former building energy modeler myself, I’ve come to learn that one of the (many) great things about energy modeling is that the core skill set is highly transferable!"

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09-17-2019: How Are Energy Modeling Careers Evolving?

Carrie Brown, Senior Technical Consultant at Resource Refocus, replies: "I’m reasonably certain that we’ll continue to have buildings in the next few decades -- and if we don’t, the future of energy modeling careers probably won’t be our top concern..."

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07-23-2019: How Can I Talk to Clients About the Uncertainty in Models?

Michael Sweeney, Energy Engineer at AKF Engineers, replies: "My first instinct is to recommend that you bang loudly on your client’s desk while shouting the aphorism (generally attributed to the statistician George Box), ‘ALL MODELS ARE WRONG BUT SOME ARE USEFUL!!!!!"

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06-19-2019: How Do You Get People Excited About Building Energy Modeling?

Dan Macumber, Engineer with NREL Commercial Buildings, replies: "This question really caught me by surprise, I mean who does not get excited by heat pumps, they are practically engineering magic!"

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05-22-2019: What is the one thing no one tells you about building performance modeling?

Erik Kolderup, Principal at Kolderup Consulting, replies: "Dear Wondering, Only one thing? Many are the unspoken secrets of the ancient modelers! But here’s one...

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