Warehouses and distribution centres are large, tall and lightly occupied, but they still need to be heated through Canadian winters and ventilated for the people and vehicles working inside. With clear heights of 10 to 12 m (32 to 40 ft) or more, dozens of dock doors and floor areas measured in hectares, the heating strategy has a major effect on operating costs.
This guide covers the main heating systems, ventilation requirements, and the details that cause problems in practice.
What drives warehouse heating loads
Unlike offices, warehouse loads are dominated by the envelope and by air entering the building:
- Roof and wall losses: a large roof area means envelope insulation levels matter a lot. Energy codes set minimum insulation for heated warehouses, though requirements vary by province and by whether the space is classed as semi-heated.
- Infiltration through dock doors: each time a dock door opens without a sealed trailer, cold outdoor air pours in. In a busy cross-dock facility, this can be the largest single heating load.
- Ventilation air: required outdoor air for occupants and to dilute forklift emissions.
- Stratification: warm air rises, so temperatures near a 12 m roof can be 5 to 10 K higher than at floor level with conventional forced-air heating, increasing roof losses.
Internal gains from people and lighting are small, though conveyor motors and battery chargers add some heat. A sound heating load calculation should account for door operation, not just steady-state envelope losses.
Typical setpoints
Warehouse temperatures are usually set to protect goods and provide reasonable working conditions rather than office comfort:
| Area | Typical winter setpoint |
|---|---|
| General storage, unoccupied | 5 to 10 C (41 to 50 F), or as stored goods require |
| Active picking and storage areas | 13 to 16 C (55 to 61 F) |
| Shipping and receiving docks | 10 to 15 C (50 to 59 F) |
| Offices, lunchrooms, washrooms | 20 to 22 C (68 to 72 F) |
Sprinklered areas with wet-pipe systems must be kept at or above 4 C (40 F) under NFPA 13, which sets the absolute minimum for most heated warehouses. Some stored products, such as beverages, paint and pharmaceuticals, have their own temperature requirements.
Heating system options
| System | How it works | Strengths | Limitations |
|---|---|---|---|
| Gas-fired infrared tube heaters | Radiant tubes heat floor and objects directly | Low stratification, quick recovery after door openings | Need clearance to stored goods and sprinkler heads |
| Gas-fired unit heaters | Fan blows air across a heat exchanger | Low first cost, simple | Stratification, uneven temperatures |
| Direct-fired make-up air units | Burner fires directly into outdoor airstream | Very high combustion efficiency, provides ventilation | Combustion products enter the space, limited by code |
| Indirect-fired make-up air or rooftop units | Heat exchanger separates flue gases | Can recirculate | Lower efficiency than direct-fired |
| Hydronic radiant floor | Warm water in slab | Very even floor temperatures | Slow response, costly in large slabs |
| Heat pumps (air-to-air or air-to-water) | Electric heat pumping | Supports decarbonization | Capacity at low outdoor temperatures, electrical service |
Radiant heating
Low-intensity infrared tube heaters are common in Canadian warehouses because they heat people, racking and the floor directly rather than the air. The warm floor then helps the space recover quickly after a dock door has been open. Mounting heights and clearances to combustibles, racking and sprinkler heads are set by the manufacturer's certification and CSA B149.1.
Direct-fired heating
Direct-fired gas heaters are very efficient because all the combustion heat goes into the airstream. The combustion products, including water vapour, CO2 and small amounts of CO and NO2, enter the building. CSA B149.1 and the appliance standards under the CSA/ANSI Z83 series set the conditions for their use, including requirements for adequate ventilation and limits on recirculation. Some newer units are designed to recirculate a portion of indoor air under strict controls. See direct-fired and indirect-fired make-up air units and CSA B149 gas installations for detail.
Destratification
High-volume low-speed (HVLS) fans, typically 3 to 7 m (10 to 24 ft) in diameter, gently push warm air from the ceiling back down to the floor. In winter this reduces the temperature difference between floor and roof and can lower heating energy. In summer, the same fans provide cooling by air movement for workers. They should be coordinated with sprinkler layouts and, where required by the fire code or authority, interlocked to shut down when sprinklers activate.
Ventilation
Warehouses need outdoor air for occupants and, where fuel-powered forklifts operate, for diluting carbon monoxide, nitrogen dioxide and other exhaust gases. The amount of outdoor air should be based on the governing code, typically ASHRAE 62.1 through Part 6 of the NBC, plus whatever is needed to keep contaminant concentrations below provincial occupational exposure limits.
Practical points:
- Propane and natural gas forklifts: require continuous ventilation and, ideally, CO monitoring with ventilation control. Well-tuned engines produce far less CO than poorly maintained ones.
- Electric forklifts: eliminate combustion emissions but introduce battery charging areas. Lead-acid batteries release hydrogen during charging, so charging rooms need ventilation to prevent hydrogen accumulation. Lithium-ion batteries largely avoid this but bring their own fire safety considerations.
- Gas detection: CO and NO2 sensors controlling exhaust fans and make-up air, similar to parking garage systems, are a good approach. See garage ventilation and CO/NO2 detection.
Dock doors
Dock doors deserve careful design because they control so much of the heating load:
- Use dock seals or shelters so the trailer seals against the building when loading.
- Specify insulated, well-sealed overhead doors.
- Install fast-acting high-speed doors at interior openings between heated and less-heated zones.
- Consider air curtains or dock-area heaters at the busiest doors.
- Keep the building near neutral or slightly positive pressure so air does not rush in when doors open.
Negative building pressure, caused by exhaust fans running without make-up air, makes every door opening worse.
Cooling
Most Canadian warehouses are not mechanically cooled, though summer heat in the racking can reach uncomfortable levels. Evaporative cooling in drier climates such as the Prairies, ventilation-based night flushing, HVLS fans and spot cooling at workstations are common approaches. Facilities storing temperature-sensitive products may need full cooling or separate refrigerated zones.
Energy opportunities
The biggest savings usually come from controlling infiltration at docks, reducing setpoints in storage-only areas, adding destratification fans, controlling ventilation with gas sensors, and replacing old standing-pilot unit heaters with modern condensing or radiant equipment. An energy audit can rank these for a specific site.
Key takeaways
- Envelope losses and dock door infiltration dominate warehouse heating loads.
- Wet-pipe sprinkler areas must be kept at or above 4 C (40 F), which sets the minimum heating requirement.
- Radiant tube heaters and direct-fired make-up air are common, each with specific code requirements under CSA B149.1.
- HVLS destratification fans reduce winter heating energy and provide summer air movement.
- Forklift emissions or battery charging dictate much of the ventilation design.
- Dock seals, fast doors and correct building pressure are the most effective ways to control heating costs.
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