⚙ Process Heat Gain
🔥 Makeup Air Heating Load
Sizing Breakdown
Full Calculation Table
| Component | Basis | Value | Result |
|---|
How to Use the Industrial HVAC Calculator
Choose the category closest to your facility's equipment mix for a default heat-to-space conversion factor, or select Custom for a project-specific value.
Enter total connected equipment power and a realistic operating load factor reflecting actual typical operation rather than nameplate rating.
Enter floor area, ceiling height, and target air changes per hour for general ventilation to determine required exhaust and makeup airflow.
Click Calculate Industrial HVAC to see process heat gain, required makeup airflow, and heating load for that makeup air at winter design conditions.
Understanding Industrial HVAC Sizing
Industrial facility HVAC differs from office or retail design in two key ways: process equipment often generates substantial heat gain that has little to do with occupancy, and general or process exhaust requirements drive makeup air needs that can dominate the heating load in Canadian winters. Getting both of these right matters more for industrial spaces than the typical comfort-cooling calculations used elsewhere.
Process Heat Gain: Not All Equipment Power Becomes Space Heat
Total connected equipment power is only a starting point. Most equipment does not run continuously at full nameplate rating, which is why an operating load factor, commonly 40 to 70 percent and conceptually similar to the electrical demand factor used for service sizing, adjusts down to realistic typical power draw. Beyond that, not every watt of operating power converts into heat released into the surrounding space. Motor-driven equipment like conveyors and machining tools typically release 80 to 95 percent of their operating power as space heat gain, while thermal processes like ovens and dryers may release a smaller fraction into the space if much of the heat leaves with the product itself or through dedicated process exhaust.
General Exhaust and the Makeup Air It Requires
Any air an industrial facility exhausts, whether through general ventilation fans or process-specific exhaust hoods, has to be replaced by makeup air or the building will develop negative pressure. Negative pressure makes exterior doors difficult to open, pulls unconditioned air in through building envelope gaps in uncontrolled locations, and can cause dangerous backdrafting of combustion appliances, a life safety concern the National Building Code of Canada addresses through its combustion air and makeup air provisions. This calculator sizes general exhaust from a target air change rate, then calculates the makeup air needed to replace it.
Partial Tempering Instead of Full Comfort Conditioning
Many industrial makeup air systems only temper incoming outdoor air to a minimum acceptable temperature, often 12 to 16 degrees Celsius, rather than heating it fully to a typical office comfort setpoint near 20 to 22 degrees. Industrial spaces frequently tolerate a wider temperature range than occupied comfort spaces, and this partial tempering approach can substantially reduce heating energy compared to full comfort conditioning of the entire makeup air volume, especially in cold Canadian winters.
Comparing to Warehouse and Other Specialty Facility Types
Industrial process facilities with significant equipment heat gain differ from pure storage warehouses, which typically have minimal internal heat sources and are covered separately by the warehouse HVAC calculator, a distinction the ASHRAE Handbook, HVAC Applications volume treats as separate facility categories in its industrial environments chapters. If your facility combines both process areas and storage space, consider running each area separately for a more accurate combined result.
Life Safety and Contaminant-Specific Exhaust
Processes involving welding, chemical handling, or combustion may require significantly higher exhaust rates driven by specific contaminant control requirements rather than the general ventilation air change rate this calculator uses as a starting point, and the resulting fan itself should be checked against the exhaust fan sizing calculator once the contaminant-driven airflow is known. Always confirm actual exhaust requirements against applicable workplace safety standards for your specific process, and see the smoke control calculator for life safety exhaust considerations in larger industrial spaces.
Frequently Asked Questions
Process heat gain is typically estimated by multiplying total connected equipment power by an operating load factor, since equipment rarely runs at full nameplate power continuously, then applying a further factor for how much of that electrical power actually converts to heat released into the space versus being carried away in the product or process itself. Motor-driven equipment commonly converts 80 to 95 percent of input power to space heat gain, while equipment with significant product heating, like ovens or dryers, may release a smaller fraction into the surrounding space if most of the heat leaves with the product or through dedicated exhaust.
Any air removed from a building through exhaust fans has to be replaced, or the space will develop negative pressure that makes doors hard to open, pulls in unconditioned air through building gaps, and can cause combustion equipment backdrafting. Makeup air units supply outdoor air, conditioned to an acceptable temperature, to replace what general exhaust and process exhaust remove from the space. See the makeup air unit sizing calculator for dedicated makeup air unit design.
Not always. Many industrial makeup air applications only temper outdoor air to a minimum acceptable temperature, often 12 to 16 degrees Celsius, rather than conditioning it to full occupied comfort temperature, since industrial spaces frequently tolerate a wider temperature range than office or retail environments. This significantly reduces heating energy compared to a full comfort-conditioning approach.
General industrial ventilation commonly targets 4 to 10 air changes per hour for spaces without significant process contaminant generation, while spaces with welding, chemical processes, or combustion equipment may need considerably more, driven by specific contaminant control requirements rather than a general ventilation rate. Always confirm actual requirements against applicable workplace safety and industrial ventilation standards for the specific process involved.
Related HVAC Tools
Pure storage space alternative
Dedicated makeup air unit design
Life safety exhaust design
Occupancy-based ventilation comparison
Process cooling freeze protection
High-density process cooling analog
Confirm exhaust/makeup air balance
Office or support space air handling