HVAC Design for Restaurants, Gyms, and Retail Fitouts

Commercial kitchens must exhaust air at a minimum of 250 L/s per m² of cooking surface. This is set by AS 1668.1, Section 6. A 10 m² cook line needs at least 2,500 L/s of exhaust. The hood must capture all smoke, steam, and grease at the source.

All that exhausted air must be replaced. Make-up air is typically 65% to 85% of the exhaust rate. Without it, the kitchen runs under negative pressure. Doors slam. Smoke spills into the dining room. The exhaust fan works harder and burns out faster.

The dining area needs its own cooling system, separate from the kitchen. Fresh air rates for diners are 10 L/s per person per AS 1668.2, Table A1. A 60-seat restaurant needs at least 600 L/s of outdoor air to the dining space alone.

Exhaust hoods over cooking equipment need grease filters. Heavy-duty cooking (open flame, chargrills) also needs a fire suppression system inside the hood. The duct from the hood to the fan must be grease-rated and fire-rated per AS 1668.1.

Engineering design: $8,000 to $20,000 depending on kitchen size and complexity. Installation: $40,000 to $150,000+ depending on exhaust run length, make-up air, and whether the building has existing ductwork.

A person sitting in an office generates about 75 watts of heat. A person exercising generates 200 to 400 watts. A gym with 100 people working out adds 20 to 40 kW of heat from bodies alone. The cooling system must handle this on top of lighting, solar gain, and equipment loads.

AS 1668.2 requires outdoor air for gyms based on occupancy and activity level. For high-activity spaces, plan for 10 L/s per person. A 200-person gym floor needs at least 2,000 L/s of outdoor air. This is a large volume that must be conditioned before entering the space.

Moving air feels cooler. Ceiling fans or high-volume low-speed (HVLS) fans reduce the perceived temperature by 2 to 3 degrees. This lets you set the thermostat higher and save on cooling energy. HVLS fans are common in open-plan gyms with high ceilings.

People sweating in a closed space raise the humidity fast. If relative humidity stays above 70%, the space feels clammy and surfaces grow mould. Dehumidification may be needed in coastal and subtropical locations. Pool areas and hot yoga studios always need it.

Engineering design: $5,000 to $15,000. Installation: $30,000 to $100,000 depending on floor area, ceiling height, and whether the space has existing mechanical services.

Most retail spaces need straightforward comfort cooling. The design temperature is typically 22 to 24°C in summer. Occupancy is lower than a gym or restaurant, so the fresh air load is smaller. Standard occupancy rates from AS 1668.2 apply.

Every new HVAC installation in a commercial building must comply with NCC 2025, Part J6. This sets minimum equipment efficiency, ductwork insulation, zoning, and controls. A Section J report or JV3 energy model is required for the construction certificate.

Split systems suit small tenancies. VRF systems suit multi-zone retail with different areas needing different temperatures (e.g., a showroom with a separate office and storeroom). Ducted packaged units suit large format retail like furniture stores or supermarkets.

Many retail fitouts happen inside existing shopping centres or strip retail. Check what the landlord provides. Some centres supply chilled water or condenser water. Others give you a bare shell with nothing. The base building system dictates your options.

Engineering design: $3,000 to $8,000. Installation: $15,000 to $60,000 depending on tenancy size, system type, and base building provisions.