Calculate heating and cooling loads for commercial buildings. Accounts for high internal gains from lighting, equipment, and occupancy that dominate commercial loads vs. residential envelope loads.
Calculate chiller plant cooling load from building loads plus distribution losses. Size centrifugal, screw, and scroll chillers. Output in tons and kW with IPLV efficiency analysis.
Size cooling towers from chiller heat rejection, wet-bulb temperature, and tower approach. Calculate GPM, fan power, and blowdown requirements for open and closed-circuit towers.
Size air handling units from zone loads and outdoor air requirements. Calculate supply airflow, cooling coil, heating coil, fan, and filter sizing for single-zone and multi-zone AHUs.
Size variable air volume terminal units from zone peak cooling load and minimum ventilation airflow. Calculate maximum and minimum CFM, reheat coil capacity, and duct connections.
Calculate system diversity factor for VAV central plant sizing. Determine the realistic simultaneous peak load vs. sum of zone peaks to right-size chillers and AHUs.
Calculate economizer hours and energy savings for your climate. Determine dry-bulb and enthalpy changeover setpoints and annual free-cooling hours from ASHRAE weather data.
Evaluate waterside free cooling potential using cooling tower water instead of mechanical chiller cooling. Calculate available hours and plate-and-frame heat exchanger sizing for Canadian winters.
Size packaged rooftop units for commercial applications. Calculate required cooling tons and heating MBH for single-zone constant volume and multi-zone VAV RTU configurations.
Design chilled and condenser water glycol loops for freeze protection in Canadian climates. Calculate glycol percentage, flow rate derating, pipe sizing, and pump head for primary-secondary systems.
Size dedicated makeup air units for commercial spaces with high exhaust requirements. Calculate heating and cooling capacity for 100% outdoor air units feeding restaurant and industrial exhaust systems.
Size dedicated outdoor air systems that decouple ventilation from space conditioning. Calculate neutral-air supply capacity, dehumidification load, and pairing with parallel fan-coil or VRF terminals.
Calculate minimum outdoor air requirements for commercial zones by occupancy type and floor area, following the ASHRAE 62.1 Ventilation Rate Procedure adopted across Canadian provincial codes.
Design low-velocity floor-level supply ventilation systems for atriums, auditoriums, and high-ceiling commercial spaces. Calculate stratification height and effective ventilation rate.
Size underfloor air distribution plenums for open-office commercial buildings. Calculate plenum pressure, floor diffuser airflow, and stratification comfort zone height.
Calculate total energy recovery effectiveness for enthalpy wheels in commercial AHUs. Determine sensible and latent recovery, preheat savings, and cross-contamination purge sector sizing.
Calculate sensible heat recovery wheel effectiveness for commercial ventilation air preheat. Estimate annual heating energy savings for Canadian climates using bin-hour weather data.
Size 2-pipe and 4-pipe fan coil units for perimeter zones. Calculate coil capacity, chilled and hot water flow rates, and fan airflow for hotel, office, and hospital fan coil applications.
Size induction diffusers and induction terminal units for perimeter zone conditioning. Calculate primary air ratio, induced room air volume, and total delivered capacity.
Calculate radiant ceiling panel cooling and heating capacity for commercial offices. Determine surface temperature limits, condensation risk, and required DOAS latent capacity pairing.
Calculate supply, return, and exhaust airflow balance to maintain positive or negative building pressurization. Determine vestibule makeup air and stair pressurization fan sizing.
Calculate smoke control system exhaust and makeup airflow rates for atrium and stairwell pressurization per NFPA 92 principles, referenced by the National Building Code of Canada.
Estimate building connection load, chilled water flow, and energy transfer station sizing for buildings served by a district cooling plant, common in Toronto and downtown Vancouver.
Calculate cooling load from server rack heat density in kW per rack. Size CRAC/CRAH units, determine required airflow for hot aisle/cold aisle containment, and estimate PUE impact.
Calculate air change rates and HEPA filter face velocity for ISO classified cleanrooms. Determine makeup air, pressurization cascade, and recirculation airflow by cleanliness class.
Calculate ventilation and pressurization requirements for hospital spaces including operating rooms, isolation rooms, and patient wards per CSA Z317.2 guidance for Canadian healthcare facilities.
Size guestroom PTAC and fan coil units alongside corridor and public space HVAC. Calculate diversity between guestroom loads and common area loads for hotel central plant sizing.
Calculate office building HVAC loads accounting for open-plan occupant density, plug loads, and perimeter zone solar exposure. Compare VAV, fan coil, and RTU system options.
Calculate HVAC loads for retail spaces with high door-opening infiltration, display lighting heat gain, and variable occupancy. Size RTUs for strip mall and big-box retail formats.
Calculate kitchen exhaust hood makeup air, dining area comfort load, and grease exhaust ductwork sizing for restaurant HVAC per CSA B149 and NFPA 96 principles.
Calculate classroom ventilation and cooling loads based on student density. Size unit ventilators and gymnasium HVAC for Canadian K-12 schools with CO2-based demand control.
Calculate heating and destratification loads for high-bay warehouse spaces. Size unit heaters, HVLS fans, and loading dock makeup air for Canadian industrial warehouses.
Calculate process heat gain, general exhaust, and makeup air for industrial facilities. Account for equipment heat loads and required air changes for manufacturing spaces.
Commercial HVAC: What's Different from Residential
Commercial buildings are dominated by internal gains: people, lighting, computers, and process equipment. In a residential home, the envelope (walls, windows, roof) drives most of the heating and cooling load. In a well-insulated commercial office, internal gains from 1 watt per square foot of equipment and 1 occupant per 150 ft² can exceed the envelope load entirely, meaning some perimeter zones need cooling even in winter.
Central Plant vs. Distributed Systems
Buildings above roughly 50,000 ft² typically use central chilled water plants with AHUs and cooling towers. Below that, packaged rooftop units (RTUs) or multi-zone heat pumps are usually more economical. The inflection point depends on local utility rates, equipment costs, and building geometry. The commercial load calculator gives you the numbers to make that call.
VAV: The Dominant Commercial System Type
Variable air volume systems control zone temperature by modulating airflow from a central AHU rather than cycling equipment on and off. They're more efficient than constant volume systems at part load (which is most of the time) and work well in multi-zone buildings with simultaneous heating and cooling requirements. Size VAV boxes with the VAV box sizing calculator after determining zone loads.
Economizer: The Most Overlooked Free Cooling Opportunity
ASHRAE 90.1 requires air-side economizers in most Canadian climates. A properly set economizer can deliver 800-1,200 hours of free cooling per year in Toronto, and over 2,000 hours in Vancouver. The economizer calculator quantifies this for your specific climate.
Related Tools You May Need
- After sizing your chiller plant, use the cooling tower calculator to size heat rejection and the glycol system calculator for freeze protection.
- For dedicated outdoor air, pair the DOAS calculator with the energy recovery wheel calculator to reduce heating and cooling energy on ventilation air.
- Check minimum outdoor air requirements with the commercial ventilation calculator before finalizing AHU sizing.
- For building-type-specific sizing, see the hotel, hospital, office, and school HVAC calculators.
- Evaluate free cooling potential with the air-side economizer calculator and waterside economizer calculator.
Frequently Asked Questions
Commercial HVAC systems handle much larger buildings with internal gains from people, lighting, and equipment that often dominate the cooling load rather than the building envelope. Commercial systems also commonly use central plants with chillers and cooling towers, multi-zone air handling, and dedicated outdoor air systems, none of which are typical in residential HVAC design. Start with the commercial load calculator to see the difference firsthand.
Start with an accurate building cooling load, add a margin for distribution losses, then divide by 3.517 kW per ton to get required tonnage. Use our chiller plant calculator to work through chilled water flow, condenser water flow, and per-chiller sizing for a multi-chiller plant.
A variable air volume system controls zone temperature by modulating supply airflow from a central air handler rather than cycling equipment on and off. VAV systems are common in multi-zone commercial buildings with varying occupancy and internal loads across different areas. See the VAV system diversity calculator to size the central plant around realistic simultaneous demand.
A DOAS makes sense when you want to decouple ventilation air handling from zone-by-zone sensible cooling, commonly paired with fan coils or VRF terminals. It is especially common in buildings with high outdoor air requirements relative to sensible load, such as classrooms or densely occupied conference spaces. Use the DOAS calculator to size neutral supply capacity and dehumidification load.
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