— A commercial estimating tool from the Applied Desk —
Commercial Load Estimate
Quick HVAC load estimator for light commercial buildings — based on cfm's internal Excel load calc, ported to a printable web form. Enter dimensions, glass, application, and design conditions; get sensible/latent btuh, total tons, heating output, sq-ft/ton, and a per-system breakdown ready to print.
Anything you fill in here shows up at the top of the printable estimate — handy when you're handing the report to a customer or filing it with a project. Skip it for back-of-the-napkin sizing.
Building Dimensions — must be entered for air change / infiltration calc to work
Roof
Roof R-Value BuilderType thickness (in) for each layer of the roof / ceiling assembly; net R is calculated below. R/in values are editable.
Insulation
Wood & Sheathing
Masonry
Other
Walls
Define each wall construction. Use Shared (Δ T = 0) for any wall bordering a conditioned neighbor.
Auto wall SF: 0Defined: 0
Wall R-Value BuilderType thickness (in) for each layer of construction; net R is calculated below. R/in values are editable. Apply sends the result to whichever wall type opened this builder.
Insulation
Wood & Sheathing
Masonry
Other
Lighting
⚠ Pick an option below — lighting load is 0 until one is selected.
Or count actual fixture watts / floor SF.
Typical intensity (W/SF):
Standard office incandescent: 2
Standard office LED: 0.5
Or use actual fixture count / floor SF
For each exposure, enter the total square feet of glass that faces that direction. Two glass types are
supported (e.g., main window package + skylights) — leave a column at 0 if you only have one type.
Type 1 — SF of glass
Direction the glass faces
Type 2 — SF of glass
Cooling factors are btuh / SF per type (1/2/3/4):
N: 44/35/34/25 · NE: 51/42/38/29 · E: 69/60/49/40 · SE: 79/70/56/47 · S: 89/80/61/52 · SW: 141/132/93/84 · W: 135/126/90/81 · NW: 78/69/55/46 · Skylights: 175/166/114/105.
Heating factors per type are 88/44/88/44 (winter Δh applied separately).
Application & People
Auto-calculated from floor SF × occupancy density (per IMC application). Type to override; press ↻ to restore.
Pick the activity that best matches the application. Switches to Custom automatically if you edit the per-person values below.
Multi-activity grid is active — the simple per-person values above are being ignored and the grid totals below are used instead.
Enter the # of people in each activity. Sens/Lat per person are pre-filled from the table below but you can override any value.
Totals + weighted-average per-person values are computed live; any non-zero entry here overrides the simple per-person inputs above.
⚠ Pick Insulated or Uninsulated — dock load is 0 until one is selected.
Dock Door type 2
⚠ Pick Insulated or Uninsulated — dock load is 0 until one is selected.
Truck Type
⚠ Pick a truck type below.
Electric Forklifts — Count by Class
Avg HP defaults to the middle of each class's typical range — override if the owner knows the actual motor size.
Class I — Sit-down counterbalanced (3K–6K lb) · typical 10–15 HP
Class II — Narrow-aisle reach / order picker · typical 5–10 HP
Class III — Walkie / rider pallet jack · typical 1–3 HP
Default 50% load × 50% duty = ~25% of nameplate. Bump up for busy DC operations, down for light-duty.
Load factor (50% default) — how hard the truck is working when it IS moving.
Duty cycle (50% default) — what fraction of the shift the truck is actually moving or lifting at all.
Battery Chemistry & Charging
⚠ Pick a battery chemistry — affects whether charger load shows up at peak cooling hour.
Include charger heat in peak cooling load?
Charger heat will be excluded from the main building load — it should be calculated separately for the battery room.
Propane / LPG Forklifts — Count by Class
Propane combustion releases ~91,500 BTU per gallon — virtually all of it stays in the building when there's no exhaust capture.
Defaults below are typical fuel-burn rates while operating; override if the owner has actual consumption data.
Class IV — Cushion-tire IC, indoor (3K–8K lb) · typical 1.0 gal/hr
Duty cycle = fraction of the design hour the engine is running (typically 0.5–0.7 for indoor warehouse operations). With propane, the engine is either on or off — even at idle it's burning fuel — so we use a single duty cycle instead of load × duty.
⚠ Outside air note: propane forklifts in indoor warehouses typically require additional outside air for CO/CO₂ dilution to meet OSHA and local code (rules of thumb: 5,000–10,000 CFM per truck).
This calc does not auto-add ventilation OA — bump OA cfm in the Ventilation section manually based on the AHJ's requirement for the application.
Forklift active heat (sensible): 0 BTU/hrCharger heat (peak): 0 BTU/hrPropane combustion latent: 0 BTU/hrTotal to building load: 0 BTU/hr
Internal Loads
Computers— sensible heat only. Defaults: 110 W desktop, 80 W laptop. Adjust as needed.
Motors— sensible heat only. Total nameplate HP × % usage × 2545 BTU/hr per HP.
Motor load: 0 BTU/hr sensible
For each item, enter Voltage, Phase, Amp draw, Quantity, and % Run time.
Watts and BTU/hr are auto-calculated. Sensible heat only.
Total equipment sensible load: 0 BTU/hr
Motor btuh: HP × % usage × 2545 (full nameplate at 100%).
Refine with: HP × % usage × % nameplate amp draw × (1 − efficiency).
P=I·V (3-phase: ×√3); btuh = W × 3.415.
Design Conditions
Indoor wet bulb is computed from indoor DB + RH using ASHRAE psychrometric formulas. The cooling tons formula is preserved exactly: MAX( Sensible/0.725 ÷ 12000, (Sensible+Latent) ÷ 12000 ), which over-sizes when SHR drops below 0.725.
Ventilation & Infiltration
Defaults to MAX of vent / exhaust / infiltration cfm. Type to override; press ↻ to restore the default.
Commercial Load Calc