Three reports that get requested in the same breath at plan review — and get confused constantly. Here's what each one actually is.
If a plan reviewer kicked your permit back asking for "the energy report" or "the load calc" and you're not sure which document they mean, you're not alone — these three reports get lumped together constantly, and they're not interchangeable. REScheck and COMcheck prove your building's envelope (insulation, windows, air sealing) meets the energy code. Manual J calculates how much heating and cooling capacity your HVAC equipment needs. One is a compliance report for the shell of the building; the other is a load calculation for the equipment inside it. Building departments frequently want both, on different forms, from different software, and confusing them is one of the most common reasons a permit sits on hold.
This page exists to end that confusion. Below is exactly what each report does, who requires it, and when a project needs more than one.
REScheck is a free U.S. Department of Energy compliance tool that proves a residential building's envelope — insulation levels, window and door U-factors, air leakage targets — meets the IECC (International Energy Conservation Code) or a state-adopted equivalent. It does not touch equipment sizing at all. REScheck runs a "UA trade-off" calculation: it adds up the heat-loss rate (U-factor × area, or "UA") of every wall, window, ceiling, and floor in your proposed design and compares that total against what a code-minimum building in your climate zone would produce. If your total is equal to or lower, you pass — even if individual components, like an oversized window wall, fall short of the prescriptive table, as long as something else (extra ceiling insulation, better wall R-value) makes up the difference elsewhere. REScheck applies to detached one- and two-family homes and multifamily buildings three stories or less. It is envelope-only: no mechanical equipment, no BTU numbers, no tonnage.
COMcheck is the commercial counterpart to REScheck, used for commercial buildings, mixed-use projects, and multifamily buildings taller than three stories, and it checks more than just the envelope. Where REScheck evaluates walls, windows, and insulation, COMcheck also folds in lighting power density and, depending on the compliance path chosen, mechanical system efficiency requirements under the commercial provisions of the IECC or ASHRAE 90.1. If your project is a single-family home, duplex, townhouse, or a low-rise multifamily building, you almost certainly need REScheck, not COMcheck. If it's a commercial tenant improvement, an apartment building over three stories, or mixed residential/commercial, COMcheck is the correct tool. Both are produced by the same DOE Building Energy Codes Program and both output a stamped compliance certificate, but they are not interchangeable submittals — using the wrong one is an automatic bounce at intake.
Manual J is the ACCA (Air Conditioning Contractors of America) heat-loss and heat-gain calculation that determines the actual heating and cooling load, in BTUH, that a specific house needs — and it has nothing to do with insulation compliance. It takes inputs like square footage, window area and orientation, insulation R-values, infiltration rate, and local design temperatures, and produces a room-by-room and whole-house load number. That number is what a contractor uses to select equipment tonnage under Manual S. Many jurisdictions require Manual J for new HVAC installations, heat pump conversions, furnace and AC replacements, and new home construction — see our Do I need a Manual J? guide for the full breakdown by project type. Manual J is a sizing document, not an envelope compliance document. It never asks about your window U-factor limits against a code table; it asks how many BTUs it takes to heat and cool the space you actually built.
No — REScheck approval only confirms your envelope meets the energy code; it says nothing about whether your HVAC equipment is sized correctly. This is the single most common point of confusion we see. A homeowner or GC submits a passing REScheck report and assumes the mechanical side of the permit is covered, then gets a plan review comment asking where the Manual J load calculation is. REScheck and Manual J are graded against completely different standards, produced by different software, and reviewed by different sections of the code (IECC envelope provisions vs. IRC Chapter 14 / IECC R403.7 equipment-sizing provisions). Passing one tells the plan reviewer nothing about the other.
Yes, in most cases — new construction and many additions or HVAC-touching remodels need both, because they trigger two separate code requirements. A new single-family home needs a REScheck for envelope compliance and a Manual J (feeding a Manual S equipment selection) for HVAC sizing — that's two reports, two purposes, submitted together in most jurisdictions. A room addition that also adds or extends the HVAC system typically needs both as well, though the REScheck only evaluates the new envelope area, not the whole existing house (see our REScheck for additions guide for how that trade-off works). A straight furnace or AC replacement with no envelope work usually needs only a Manual J, not a REScheck, since nothing about the building shell changed. When in doubt, check with your local building department's permit checklist — requirements vary by jurisdiction and by which edition of the IECC/IRC has been adopted locally.
Match your project type to the report: envelope or insulation work → REScheck; HVAC install, replacement, or new construction mechanical system → Manual J (and Manual S for equipment selection); commercial or 4+ story multifamily → COMcheck instead of REScheck. If your project touches both the shell and the mechanical system — which most new construction and many additions do — plan on submitting both. Our Manual J page covers our $249 Manual J report built in ACCA-approved Cool Calc software, matched to your plans, backed by a fix-it guarantee if the building department rejects it. Our REScheck page covers our REScheck service.
Start with the primary sources rather than a contractor's blog post. The DOE's Building Energy Codes Program hosts REScheck and COMcheck directly, ICC's code text is the authoritative source for IRC and IECC section language, and ACCA publishes the Manual J, Manual S, and Manual D standards along with the current approved-software list.
Travis Smith, ICC-Certified Residential Energy Inspector / Plans Examiner
Travis reviews residential permit submittals for a living and built The Plans Examiner so contractors, builders, and homeowners stop losing weeks to a report the AHJ won't accept. Manual J reports are $249, built in ACCA-approved software, matched line-for-line to your plans — accepted by the building department or we fix it free.
ICC-certified plans examiner — private review for your permit package. Travis Smith — ICC-Certified Residential Energy Inspector / Plans Examiner · E&O insured · general contracting background in Washington. The person who reviews your plans at the building department is a plans examiner. I hold the same ICC certification — except I work for you.