How energy modeling can set you up for success
PHOTO COURTESY BRIGHTBUILT HOME.
Building Science 101
By Parlin Meyer
FOR HOMEOWNERS considering a new build or renovation, energy modeling might sound like a complex, technical term, but it’s actually an incredibly valuable tool that ensures your home is designed to perform optimally—both in energy efficiency and comfort. By leveraging advanced software, energy modeling allows us to predict how a home will function under various conditions, offering insights that guide design choices and prioritize performance. Let’s dive into how this process works and why it’s such an essential step in creating a high-performance home.
Energy modeling taps into the world of algorithms, material science and anticipated climate conditions to give us an accurate and manipulatable picture of what we can expect for building performance: accurate is very important; manipulatable is key.
By using software platforms, we can input various factors and features in a home, including:
Total amount of glazed area: all the windows and glass doors, added up
Orientation of glazing: in our climate, south is good for glass, north isn’t great
Wall assembly: the components that make up the shell of the structure–wood? steel? cellulose insulation? spray foam?
Mechanical systems: is an air source heat pump or furnace heating the structure? How are we heating water?
Key unique—and potentially shifting—factors such as number of occupants and anticipated plug loads: will this home house a family of six washing laundry every day or a frugal single professor who eschews extravagances?
WINKY LEWIS PHOTO
All these considerations are plugged into the appropriate slots, and calculations are made.
The resulting cache of building information can convey things such as:
Whether the structure might have ample roof area for a solar array that will support the entire electrical demand of the home
Whether the glazing is sufficient to the south to bring in ample solar gain, or overabundant to the north that would allow for too much heat loss
Whether more insulation is needed or whether other design tweaks would fulfill that need
Modeling serves in the preparation of a design, because we can alter the inputs until we land on the optimal confluence of aesthetics, performance and cost. It’s the scientific and mathematical guide to the best Venn diagram of our home. Energy modeling is an important tool that informs the sizing of the mechanical systems so they are right-sized to run most efficiently. Energy modeling can also be used to determine the size of a solar array required to support the home to get to net-zero, or the right insulation levels for the climate. Further, for existing homes, modeling can inform what types of interventions on the structure might be most impactful for performance or comfort—for example, helping you to decide between replacing windows or adding insulation.
Energy modeling programs abound in the world of building science, each with its own unique visuals and software interface. Some building energy modeling programs, like WUFI (a German software used to analyze the heat and moisture movement within building materials and assemblies), HERS® (Home Energy Rating System) and PHPP (used to design Passive House buildings), are favored by preeminent building scientists. Others, such as EnergyPlus and BEopt (a computer program that provides simulation-based analysis to optimize building energy), are favored by engineers. Building professionals with a more aesthetic bent, such as architects and designers, gravitate toward programs that integrate with the Building Information Modeling (BIM) software they are already using to design their buildings.
Different energy modeling programs have similar capacities, though they may focus on different key areas that are important to their users. Some programs focus on climatic conditions and more heavily weight factors such as humidity, occupancy loads or solar orientation. Others look more precisely at the building components themselves in an effort to maximize performance while minimizing structural weight or material waste. Some are more user-friendly and generate more comprehensive and easy-to-follow graphics.
It’s all really a matter of preference and priority, as the end result remains the same: outputs equal action and understanding. The predictive power of energy modeling is its most potent element— and that exists through all of these programs.
PHOTO COURTESY OF BRIGHTBUILT HOME
If you’re working with a designer on a new home or renovating your existing home, where do you go to have an energy model performed?
If your designer is already well-versed in building science, it is very likely they do energy modeling as part of their design process. If they don’t, there are plenty of independent operatives out there—building science consultants, HERS raters, and energy auditors—who can run the diagnostics for your design.
If you are a homeowner seeking to better understand your home performance, your local energy auditor should offer analytics as part of their assessment of your home. You don’t have to look too far. Agencies such as Efficiency Maine, Efficiency Vermont, Mass.gov, or a local high performance building supply vendor can offer lists of registered vendors. The Pretty Good House—a 2022 book authored by four Mainers—is an excellent primer on realistic high-performance construction and energy modeling.
As designers, energy modeling gives us an added, extremely accurate and infinitely manipulatable tool in our design kit. As tradespeople, the model offers us assurance that we can size systems in the good faith that they will operate as designed and with maximum efficiency. As builders, we can follow the metrics to test and build our buildings to a greater level of precision and durability.
For homeowners, energy modeling provides peace of mind and confidence that your home will not only meet your comfort needs but also operate efficiently, keeping energy costs down while reducing your environmental impact. Whether you’re building new or upgrading your existing home, energy modeling ensures your investment is optimized for performance, aesthetics and long-term sustainability.
This article appeared in the Spring 2025 edition of Green & Healthy Maine HOMES. Subscribe today!
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