Early-stage energy modeling assesses building performance
The demand for high-performing buildings is increasing, according to the National Institute of Building Sciences. That demand compels key stakeholders to consider all available sustainable methodologies and technologies at their disposal.
One powerful technique for assessing the performance of a building is whole-building energy modeling. It can provide substantial value to project teams because it simulates and evaluates potential energy performance, leading to better-informed design decisions, compliance certification for local energy codes and easier pathways to building certification requirements, reports the U.S. Green Building Council.
Energy modeling can assess the potential energy savings of a project at any point in the design. However, it is easier to incorporate recommended or even necessary changes when they are recognized early in the design process. Modeling analyses and results can lead the way toward the project’s energy goals and construction objectives.
Substantial opportunity for increased use
For energy modeling to translate easily into energy savings, its results and analyses should be applied early in the design process. It is estimated that building energy modeling is used for design in “20 percent of commercial new construction projects, with lower use in commercial interior, retrofit and residential projects.” This figure signals a large opportunity for future use of energy modeling in 80 percent of commercial new construction projects, and even more in other projects.
Working with a design team early in the project can help a project team explore design parameters and alternatives that might not otherwise be considered, including passive design elements such as building orientation, size of facility, function of the design, geometry/shape, building envelope materiality, window-to-wall ratio, shading and daylighting.
Incorporating these features, as well as heating, ventilating and air conditioning (HVAC) strategies, into an early-stage design energy model can optimize whole-building performance and aid in meeting project energy goals. This approach can also reduce redesign time and costs that could otherwise arise when incorporating energy modeling later in the project.
Schematic design energy modeling benefits
But what clear benefits can a project team expect to see by implementing energy modeling early in the design process? The benefits are actually multiple and diverse, including:
- Energy efficiency and certification goals are achieved more easily, due to more-informed design decisions.
- Risks, delays and setbacks are mitigated through the elimination of redesign later in the project.
- Different components and systems can be compared in order to choose those that will optimize energy efficiency and meet performance targets.
- Energy modeling in the pre-design phase can allow a project to achieve 45 percent average savings per project compared to a baseline building.
Proponent for schematic design energy modeling
NORESCO, as one of the largest energy service companies in the United States, can attest to the benefits of schematic design energy modeling based on its experience with clients. The organization has provided early-stage modeling for projects during the conceptual and schematic design phases, with energy goals ranging from those under LEED silver to near-net zero energy use.
To begin schematic design energy modeling, all that is needed are the preliminary building geometry and building operation schedules. The first step is to analyze the energy end-use breakout to identify the areas with the largest design impact. For one college campus dormitory project, early phase modeling revealed that the ventilation strategy was one of the largest end uses and needed careful design.
For an office building project, the window-to-wall ratio was investigated in detail to provide the client’s desired views. Other strategies that can be researched early include HVAC planning, such as variable air volume reheat strategies (electric versus hot water) or steam heating versus natural gas. While all end-uses — from building envelope to lighting — can be considered, part of the process is to prioritize which to investigate first to garner the largest energy savings.
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Companies: U.S. Green Building Council