When You Need an Energy Model Instead of ComCheck
If you’ve worked on a building project, you’ve probably heard of ComCheck — the free software from the U.S. Department of Energy that helps verify building code compliance. For many small and straightforward projects, it works fine.
But here’s the catch: ComCheck only works when your project fits neatly into the prescriptive path of the energy code. As soon as you hit an exception, a special condition, or a system that doesn’t match the code tables, ComCheck won’t get you there. That’s when you need to step up to a performance path energy model.
Why ComCheck Isn’t Always Enough
ComCheck is designed for simplicity. It checks things like insulation levels, window performance, and lighting power density against minimum code tables. But it can’t account for design trade-offs or advanced systems.
Common reasons ComCheck fails:
- Innovative or high-efficiency systems not listed in the prescriptive tables.
- Complex mechanical systems such as geothermal, VRF, or heat recovery chillers.
- Mixed-use buildings that don’t fit cleanly into ComCheck’s categories.
- Envelope trade-offs — e.g., better glass with lower insulation, or vice versa.
- Large buildings (over certain size thresholds) that exceed ComCheck’s scope.
When these issues come up, the reviewer or code official will often say: “You’ll need a performance path energy model.”
Other Common “Shortcut” Tools That Fall Short
ComCheck isn’t the only tool people try before realizing they need a real model. Others include:
- ResCheck (for residential): Simple checklist, but fails with multi-family or mixed-use projects.
- Lighting calculation spreadsheets: Work for basic compliance but can’t capture interactive effects of HVAC and lighting loads.
- Manufacturer calculators: Equipment vendors sometimes provide “savings calculators” — useful for marketing, but not accepted by permitting or certification authorities.
All of these are fine for quick checks, but none can stand in for a full, accepted energy model when compliance or financial incentives are on the line.
When an Energy Model Becomes Mandatory
You’ll need to move beyond ComCheck (or similar tools) and run an energy model when:
- Your code reviewer rejects ComCheck results due to an exception.
- You’re pursuing LEED certification or other programs requiring modeled performance.
- You’re applying for the 179D tax deduction or utility rebates.
- Your building is complex (labs, data centers, hospitals, mixed-use).
- You need to show trade-offs that the prescriptive path doesn’t allow.
At that point, ComCheck isn’t enough. Only a full energy model will satisfy the requirement.
Why eQUEST Is the Next Step
So, what do you do if ComCheck won’t cut it? That’s where eQUEST comes in.
- It’s free. Just like ComCheck, there’s no license fee barrier.
- It’s accepted. Code officials, LEED reviewers, and rebate programs all recognize eQUEST models.
- It’s flexible. You can model complex HVAC systems, mixed-use occupancies, and envelope trade-offs.
- It’s learnable. Compared to other advanced tools, eQUEST has the easiest learning curve — and the skills transfer to EnergyPlus, OpenStudio, and other platforms.
If ComCheck was your first step, eQUEST is the natural next step when you need to prove performance.
Conclusion
ComCheck and similar tools are a great starting point — until your project doesn’t fit the mold. At that moment, you’ll need a performance path energy model to move forward.
Instead of getting stuck or delaying permits, you can take control of the process. Learning eQUEST gives you the ability to handle these situations confidently, without relying on someone else to “bail you out” when ComCheck fails.
Take our eQUEST Training Program →
We’ll teach you how to move beyond ComCheck and build professional-grade energy models step by step.