Cafe and Bakery Ventilation Design

What You Need to Know

Cafes and bakeries generate heat, grease, moisture, and odour. The ventilation system handles all four. Get the design wrong and you face failed inspections, odour complaints from neighbours, condensation damage, and a kitchen that is too hot to work in.

Every cafe or bakery with cooking equipment needs a mechanical exhaust system designed to AS 1668.2:2024. The exhaust ductwork must comply with AS 1668.1:2015 for fire and smoke control. The building certifier will require engineering drawings before issuing a Construction Certificate (CC) or Complying Development Certificate (CDC).

Bakeries have additional challenges that most cafes do not. Deck ovens and rack ovens produce sustained high heat loads. Proving rooms need controlled temperature and humidity. Flour dust creates air quality concerns. These factors make bakery ventilation more complex and more expensive than a standard cafe fitout.

Small tenancies in shopping centres and strip retail present their own problems. Limited ceiling voids, shared risers, and landlord restrictions on roof penetrations all constrain the design. The mechanical engineer needs to assess the base building before the lease is signed.

• Kitchen exhaust rates are determined by cooking process type. A cafe sandwich press or bain-marie (Type 1 to 2) requires less exhaust than a bakery fryer or char-grill (Type 4 to 5). Minimum exhaust rate is 250 L/s per m² of cooking surface. (AS 1668.2:2024, Section 3)
• Exhaust hoods must overhang the cooking equipment by at least 150 mm for Type 1 to 4 cooking and 300 mm for Type 5. (AS 1668.2:2024, Appendix E)
• Makeup air must replace 65% to 85% of the exhaust airflow. The remainder draws in through doors and transfer grilles from adjacent spaces. (AS 1668.2:2024)
• Kitchen exhaust ductwork must be built from 1.2 mm galvanised steel or 0.9 mm stainless steel. Fire dampers are not permitted on kitchen exhaust ducts. (AS 1668.1:2015)
• Patron seating areas require a minimum 10 L/s per person of outdoor air for acceptable indoor air quality. (AS 1668.2:2024, Table 3.1)
• Kitchen exhaust exceeding 1,000 L/s must discharge vertically through the roof. The 2024 revision permits treated exhaust pathways as an alternative. (AS 1668.2:2024)
• Exhaust discharge must be located to prevent odour re-entry into the building or neighbouring properties. Minimum distances from openable windows, air intakes, and boundaries apply. (AS 1668.2:2024, Section 3.5)
• Grease filters (baffle type) are required on all exhaust hoods serving cooking equipment. Automatic fire suppression is required for Type 5 cooking (char-grilling, wok cooking, deep frying at high volume). (AS 1668.1:2015, Section 6)
• Cleaning access doors are required at every change of direction and at 3 m intervals on horizontal duct runs. (AS 1668.1:2015)
• NCC 2025 Section J energy efficiency requirements apply to all new HVAC installations, including heat recovery provisions for large exhaust systems. (NCC 2025, Section J)

Kitchen Exhaust for Cafes

A typical cafe kitchen runs a combination of a coffee machine, sandwich press, toaster, bain-marie, and possibly a small oven or cooktop. Most of this equipment falls under Type 1 to 3 cooking processes. The exhaust system is smaller and simpler than a full restaurant kitchen, but it still needs engineering design.

The hood must cover all cooking equipment with the required overhang. A wall-mounted canopy is the most common configuration in a small cafe kitchen. The exhaust rate depends on the cooking surface area and the worst-case process type under the hood. For a 2 m² cooking surface with Type 3 equipment, expect an exhaust rate of around 500 to 700 L/s depending on hood configuration.

Cafes that add char-grilling or open-flame cooking jump to Type 5, which doubles the exhaust requirement and triggers fire suppression. This is a common trap. A cafe owner who decides to add a char-grill after the fitout is complete faces a full exhaust system redesign.

Bakery-Specific Challenges

Bakeries produce significantly more heat than a standard cafe. A single deck oven can reject 15 to 25 kW of heat into the kitchen space. A rack oven rejects even more. This heat load drives the sizing of both the exhaust system and the kitchen air conditioning. Without adequate cooling, internal temperatures in a bakery kitchen reach 40 to 45 degrees Celsius during peak production.

Flour dust is an air quality concern in bakeries. While not classified as a hazardous dust at typical bakery concentrations, flour dust accumulates on surfaces, clogs filters, and creates housekeeping challenges. General exhaust ventilation in the mixing and preparation areas helps control airborne flour. Dust collection at the source (mixer, flour sifter, dough divider) is the most effective strategy for larger operations.

Proving rooms require controlled conditions, typically 27 to 35 degrees Celsius at 75% to 85% relative humidity. A dedicated split system or fan coil unit with a humidifier controls the temperature and moisture level. The proving room must have exhaust ventilation to prevent moisture migrating into the ceiling void and surrounding walls. Without this, mould growth is inevitable within months.

Dry goods and ingredient storage areas need to be kept below 25 degrees Celsius with moderate humidity. Chocolate, butter, and certain flour types are sensitive to temperature swings. A separate air conditioning zone for storage is standard in bakeries producing pastry and confectionery.

Makeup Air Strategies

Every litre of air exhausted from the kitchen must be replaced. If the makeup air system is undersized, the kitchen runs under negative pressure. Doors slam shut, exhaust hoods lose capture efficiency, and unconditioned air rushes in through every gap in the building envelope.

Tempered makeup air is air that has been heated or cooled before entering the kitchen. In Sydney's climate, tempering usually means cooling the makeup air in summer. Introducing 30 to 35 degree outside air directly into a kitchen that is already hot makes conditions worse. Tempering adds cost but improves comfort and productivity.

Untempered makeup air is cheaper to install because it avoids the cooling coil and associated controls. It works in mild weather and in kitchens with low exhaust rates. For bakeries with high exhaust volumes, untempered air in summer creates unacceptable conditions.

The ideal split is 65% to 85% of the exhaust volume supplied mechanically as makeup air, with the remainder drawn from adjacent spaces (the dining area or corridor). This slight negative pressure in the kitchen prevents cooking odours from migrating into the seating area.

Grease Filtration and Fire Suppression

All exhaust hoods in a cafe or bakery must have grease filters. Baffle-type filters are the standard for commercial kitchens. They capture grease particles before they enter the ductwork. Filters must be removable for cleaning, which should happen weekly at minimum.

For cafes and bakeries with Type 5 cooking (char-grilling, open-flame cooking), an automatic fire suppression system is mandatory under AS 1668.1. The system uses wet chemical agents that deploy automatically when duct temperature exceeds a set point. The fire suppression system also interlocks with the gas supply to shut off fuel to the cooking equipment. Budget $5,000 to $15,000 for fire suppression depending on the number of nozzle points.

Odour Control and Discharge Locations

Cooking odour is the most common source of complaints from neighbours and upper-level tenants. AS 1668.2:2024 sets minimum discharge distances from openable windows, outdoor dining areas, air intakes, and property boundaries. The discharge point must be located where prevailing winds carry odours away from sensitive receptors.

Vertical roof discharge is the preferred approach and is mandatory when the exhaust rate exceeds 1,000 L/s. For smaller systems, wall discharge may be permitted but carries a higher risk of odour complaints. Odour treatment options include activated carbon filters, UV oxidation, and electrostatic precipitators. These add ongoing maintenance costs but may be the only option when the discharge point is close to neighbours.

Outdoor Dining Area Considerations

Outdoor seating does not require mechanical ventilation, but it must not be in the path of kitchen exhaust discharge. If the outdoor area is semi-enclosed (more than 25% enclosed by walls or screens), it may be classified as an indoor space under the NCC and require mechanical ventilation. Check with the building certifier early.

Misting systems and outdoor fans are comfort measures, not ventilation. They do not replace the need for mechanical ventilation in enclosed or semi-enclosed spaces.

Small Tenancy Challenges

Strip retail and shopping centre cafes face the tightest constraints. Ceiling voids are often 200 to 300 mm, barely enough for ductwork. The exhaust riser may be shared with other tenants, limiting available duct space. Landlords restrict roof penetrations and condenser locations.

In these situations, the mechanical engineer must assess the base building before the lease is signed. Key questions: Is there a clear duct path to the roof? Is there allocated space for a rooftop exhaust fan? Is there enough electrical capacity at the distribution board? What is the landlord's policy on exhaust discharge locations? If the answers are unfavourable, the tenancy may not be suitable for a cooking operation.

Patron Seating Area Fresh Air

The dining area is a separate ventilation zone from the kitchen. AS 1668.2:2024 requires a minimum of 10 L/s of outdoor air per person in a cafe or restaurant dining space. For a 40-seat cafe, that is 400 L/s of fresh air. This can be supplied through the air conditioning system (a ducted fresh air connection to the return air plenum) or through a dedicated outdoor air unit.

The kitchen should be at slight negative pressure relative to the dining area. This prevents cooking odours and heat from migrating into the seating space. The transition between kitchen and dining zones is managed through transfer air grilles or a vestibule with a self-closing door.

NCC 2025 Energy Efficiency

NCC 2025 Section J applies to all new HVAC installations in commercial buildings. For cafes and bakeries, this means insulated ductwork, energy-efficient fans with variable speed drives where applicable, and consideration of heat recovery on large exhaust systems. A heat recovery unit on a bakery exhaust system can preheat makeup air in winter and recover cooling energy in summer, reducing operating costs. However, grease-laden exhaust must pass through effective filtration before entering a heat exchanger to avoid fouling.

Cost Guidance

Engineering design fees for a cafe or bakery ventilation system range from $3,000 to $7,000 depending on kitchen size, number of hoods, and complexity. A simple cafe with one hood and a short duct run sits at the low end. A bakery with multiple ovens, a proving room, separate storage zones, and a long riser to the roof sits at the high end.

Installation costs for the complete HVAC and ventilation system (exhaust, makeup air, air conditioning for kitchen and dining areas) typically range from $20,000 to $60,000+. The biggest cost drivers are duct run length to the roof, number of exhaust hoods, and whether tempered makeup air is required. Add $5,000 to $15,000 for fire suppression if Type 5 cooking is involved.

Ongoing costs include filter cleaning (weekly), professional duct cleaning (every 3 to 6 months), and fire suppression system inspection (every 6 months). Budget $3,000 to $6,000 per year for exhaust system maintenance in a medium-sized cafe or bakery.