It must be said that not all energy models are created equal. This post explores the ways you can use your LEED energy model for more than just compliance. By instead focusing on performance, cost-effective energy conservation measures, and energy modeling as a design tool, you can ensure a high-performance building.
Energy modeling (aka building performance modeling) has been used by architects and engineers for decades to predict energy usage, and the advent of LEED saw the widespread use of modeling across the industry.
LEED’s rigorous energy performance requirements helped set an industry standard for measuring performance and created a new generation of professionals versed in the tenets of green building.
Ironically, the value of energy modeling can be lost when teams distill program requirements down to LEED checklists and prioritize compliance with the rating system over performance of the building.
Compliance Vs. Performance
It is common for design teams on LEED projects to focus on the energy model from a compliance standpoint. After all, the goal of a LEED project is to comply with the rating system to get certified. The problem is that this approach focuses on checking boxes instead of achieving a high-performance building.
We’ve seen many architects underestimate the effect of orientation, massing, and fenestration on mechanical systems. Compliance-driven energy modeling often takes place once design development is underway (and sometimes even later), meaning that high-impact energy conservation measures (ECMs) are no longer in play or too challenging to change at that point in the design.
By this DD, systems have been designed and value engineering pushes teams to “trim the fat” and save on up-front costs, even if those VE decisions lead to poor energy performance once the building is operational.
The better alternative is to look at energy modeling through the lens of performance. Projects can significantly benefit from the energy consultant’s input as early as entitlements where major ECM’s can be used to assess performance from the start. For example, building orientation can be used to take advantage of solar heat or provide shade where needed, effectively increasing indoor comfort while decreasing heating and cooling loads. The building’s thermal mass could also be exploited to store heat and release later. Fenestration could be designed to maximize daylight to reduce the need for lighting during the day. These valuable decisions can reduce the size and cost of mechanical systems, while also developing the most cost-effective strategies to meet the owner’s performance goals.
Your Energy Modeler Matters
Not all modelers are the same either, and the perspective, recommendations, and experience they bring will vary. Architects, MEP engineers, and energy consultants are all influenced by their respective specialties.
For example, if a mechanical engineer produces a LEED energy model that is not performing as needed, they will likely look to upgrade the mechanical systems first. Similarly, an architect may prioritize the building envelope or shading. An energy consultant or LEED energy modeler, on the other hand, is system agnostic and will look at both and likely more. Each of the ECMs prioritized by the architect and MEP are valid, however, they may not always be the most cost-effective strategy. Here’s where an energy consultant can make a big difference.
An energy consultant should have a background in architecture or engineering, and above all, specializes in building performance. An energy consultant recognizes the cost implications of most ECM recommendations and the feasibility of each proposed ECM. They will be specialty-agnostic and will make suggestions based on what makes the most sense – and greatest impact – for that building. An energy consultant’s focus is on the model, so their deep understanding of the modeling software also means they can exploit every existing energy savings measure available – before even considering ECMs. Long story short, an energy consultant is an owner’s best resource to achieve a cost-effective, high-performance building – especially when brought on in the very early stages of design.
Energy Modeling Best Practices
- Ensure your energy consultant is following ASHRAE Standard 209-2018, which defines the recommended procedure for providing energy design assistance to ensure higher-performing buildings.
- Model early and often to get the most out of your energy model.
- As the design progresses, include your energy consultant in the conversation to update your energy model and evaluate performance.
- Envelope and equipment selection should follow the energy compliance report, and any changes should be communicated.
- Run VE changes through the energy model. It might turn out that you’re cutting the wrong items or the highest energy-saving systems.
- An as-built model should be run once the building is complete. This trues up any discrepancies and gives the owner a more accurate picture of how the building will perform once operational. This way, owners can better evaluate the performance of the buildings and troubleshoot performance issues.
And of course, once the building is operational you should deploy advanced commissioning and periodic energy audits.
The bottom line is that an energy consultant is ideally suited to give a broad perspective on energy performance that is less constrained by a technical specialty. And when you have the LEED energy modeler handle your models, you should engage them early. If you compartmentalize the LEED energy models to checklist compliance, you miss out on the opportunity to optimize your building’s performance and get the most value out of your energy model.
Lastly, how are you ensuring high performing buildings on your projects? We’d love to hear from you!
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