Manufacturing and Food Processing HVAC Design

What You Need to Know

Manufacturing and food processing facilities fall under NCC Class 8 (factory or laboratory). They present some of the most complex HVAC design challenges in building services engineering. Unlike commercial offices or retail, these buildings must simultaneously manage process heat loads, worker thermal comfort, ventilation for hazardous or contaminated air, and in food processing, strict temperature and humidity control for product safety.

HVAC design fees for a standard manufacturing facility typically range from $15,000 to $40,000. Food processing facilities with multiple temperature zones, clean room areas, and HACCP compliance requirements run $30,000 to $80,000+ depending on complexity. The design must address AS 1668.2:2024 ventilation rates, workplace health and safety thermal comfort requirements, and process-specific exhaust systems for fumes, dust, and chemical vapours.

The critical difference from standard commercial HVAC is that the process drives the design. The type of manufacturing, the heat generated by equipment, the contaminants produced, and the product sensitivity to temperature and humidity all dictate system selection before occupant comfort is even considered.

• NCC Class 8 buildings must comply with Section J energy efficiency provisions. Manufacturing facilities with high ventilation rates and process exhaust face particular challenges meeting Deemed-to-Satisfy requirements. JV3 modelling is frequently required. (NCC 2025 Section J)
• AS 1668.2:2024 sets minimum ventilation rates for industrial occupied zones. General manufacturing areas require a minimum of 10 L/s per person or 1.5 L/s per square metre, whichever is greater. Process areas with contaminant generation require ventilation rates calculated from the contaminant source strength. (AS 1668.2:2024 Table 4.1, Clause 4.3)
• Process exhaust systems must capture contaminants at the source. Welding fumes, dust, chemical vapours, and cooking effluent each have specific capture velocity requirements. Local exhaust ventilation (LEV) must be designed to AS 1668.2:2024 and relevant work health and safety codes of practice. (AS 1668.2:2024 Clause 5, SafeWork NSW CoPs)
• Food processing areas must maintain temperature control for HACCP compliance. Critical control points for temperature typically require ambient air between 10 and 15 degrees Celsius for raw product handling and below 5 degrees Celsius for chilled storage. The HVAC system must maintain these conditions reliably. (Food Standards Australia New Zealand, HACCP Application Guidelines)
• Positive and negative pressure zoning prevents cross-contamination. Clean zones must be maintained at positive pressure relative to raw product and waste areas. The HVAC system must provide the pressure differentials through controlled supply and exhaust air volumes. (AS 1668.2:2024 Clause 4.8)
• Cool rooms and freezer rooms must comply with AS/NZS 1677 for refrigeration systems. Integration with the building HVAC system includes condenser heat rejection, defrost drainage, and door air curtain or vestibule design to prevent moisture ingress and ice formation. (AS/NZS 1677, Food Standards Code)
• Cooling towers serving manufacturing HVAC must comply with AS/NZS 3666 for Legionella risk management. Registration, maintenance, and water treatment programs are mandatory in NSW. (AS/NZS 3666.1, NSW Public Health Act 2010)

Process heat removal is the starting point. Manufacturing equipment generates significant heat. A welding shop, injection moulding plant, or bakery oven can add hundreds of kilowatts of heat to the space. The HVAC design must quantify every heat source, including equipment, lighting, solar gains through the roof, and the process itself. Only after the heat load is established can you size the cooling system. Underestimating process heat loads is the most common design error in manufacturing HVAC.

Fume and dust extraction must be designed before comfort cooling. Process exhaust systems remove contaminated air from the building. Every cubic metre of air exhausted must be replaced with outdoor air, either conditioned or unconditioned. In a facility exhausting 20,000 L/s through process extraction, the make-up air system becomes the dominant HVAC component. Designing the comfort system without accounting for exhaust volumes leads to negative building pressure, uncontrolled air infiltration through doors and gaps, and poor indoor air quality.

Food processing demands strict temperature zoning. A typical food processing facility has multiple temperature zones: raw product receiving at 2 to 5 degrees, processing areas at 10 to 15 degrees, cooking or thermal processing at ambient, packaging at 15 to 20 degrees, and dispatch at ambient or chilled depending on the product. Each zone needs independent temperature control and the boundaries between zones need air locks, strip curtains, or rapid roll doors to maintain the temperature differential. The HVAC design must account for the thermal load of product moving between zones.

Contamination control relies on pressure differentials. In food processing, the finished product area must be at positive pressure relative to the raw product area. This prevents airborne contaminants from migrating from raw to cooked or packaged product. The HVAC system creates these pressure differentials by supplying more air to clean zones than it exhausts. Typical pressure differentials are 10 to 15 Pascals between zones. Achieving stable pressure differentials requires careful balancing of supply and exhaust air volumes and robust building envelope sealing.

Humidity control is critical for product quality. Many manufacturing processes are sensitive to humidity. Electronics assembly requires low humidity to prevent condensation on circuit boards. Food processing requires controlled humidity to prevent bacterial growth and maintain product shelf life. Cold chain environments must manage moisture to prevent ice formation and frosting. The HVAC system may need dehumidification equipment (desiccant wheels, refrigerant reheat, or dedicated dehumidifiers) in addition to standard cooling.

Evaporative cooling suits general manufacturing but not food processing. For large factory spaces where humidity is not critical, evaporative cooling costs 40% to 60% less to install and 70% to 80% less to operate than refrigerated systems. It works well in welding shops, assembly lines, and warehouses. However, evaporative cooling adds moisture to the air, making it unsuitable for food processing, pharmaceutical manufacturing, or any process requiring humidity control. Mixed facilities often use evaporative cooling in the general manufacturing area and refrigerated systems in the food processing zones.

Loading docks and dispatch areas need specific treatment. Loading docks are the interface between the controlled internal environment and the outside. Every time a dock door opens, heat, moisture, and contaminants enter the building. Design options include dock seals, air curtains, vestibule areas with independent HVAC, and rapid roll doors. For food processing, the dispatch area must maintain cold chain integrity, which may require the dock to be fully enclosed and refrigerated.

Energy efficiency is challenging with high ventilation rates. Manufacturing facilities with large process exhaust volumes face inherently high energy consumption. Heat recovery from exhaust air can reclaim 50% to 70% of the energy in the exhaust stream. Run-around coils, plate heat exchangers, and heat wheels are common recovery devices. However, the exhaust air must be clean enough for heat recovery equipment to function. Exhaust contaminated with grease, corrosive chemicals, or heavy particulates may require specialist coated heat exchangers or preclude heat recovery entirely.