AS 1668.2-2012 COMMERCIAL KITCHEN EXHAUST HOOD CACLULATOR
This calculator sizes commercial kitchen exhaust hoods to AS 1668.2:2012. For each canopy it determines the exhaust airflow needed to capture and contain the heat, smoke, grease and moisture released by the appliances beneath it, based on the hood configuration, its open dimensions and the duty of the cooking process. Getting this right is what keeps cooking effluent out of the kitchen and the wider building: too little exhaust and grease-laden vapour spills past the canopy, while too much simply wastes conditioned make-up air.
The Standard sets a capture airflow for each hood type from its open perimeter and face height — or its length, for low-proximity hoods — together with a minimum rate based on the cooking-surface area, and the greater of the two governs. The calculator applies that method to every hood in the schedule, adds a design margin, totals the system exhaust and sizes the matching make-up air as mechanical supply plus transfer air, capped at the transfer limit. Where engineered high-efficiency hoods are used it also reports the reduced airflow, and non-grease condensate hoods are sized by the capture/face-velocity method. It is intended for mechanical and building-services engineers, and the schedule that loads by default reproduces a published worked example for checking.
Step-by-Step
Running a calculation
Set the design parameters — In the settings strip, confirm the Design margin % added to the code rate, the Mechanical MUA % (the share of make-up air delivered mechanically), the High-eff. reduction % for engineered hoods, and the Condensate face velocity used to size non-grease hoods.
Identify the project — Enter the Project, Designed by, Date and Reference / Rev so the printed record is project-specific.
Add your hoods — Use Add hood, or Duplicate last, to build the schedule. For each row choose the Hood type and Cooking process, then enter the inside length and width over the capture opening, the face height H and the cooking-surface area. Expand the AS 1668.2 reference panel if you need the hood-type and cooking-process definitions.
Read each hood's result — The schedule updates as you type. For every hood it shows the open perimeter P, the configuration rate Q config, the area-based minimum Q min (250 L/s/m²), the Q design including margin, the Q high-eff figure, and which input Governs — Config, the 250 L/s/m² floor, or Condensate.
Review the system summary — The summary totals the standard and high-efficiency exhaust, converts to m³/s, and sizes the make-up air as mechanical supply plus transfer air, flagging where transfer exceeds the 1000 L/s limit. The live compliance checks highlight area-governed hoods, non-grease hoods, solid-fuel duties and any missing inputs.
Check the compliance notes — The notes section sets out the supporting requirements (minimum rate, worst-case capture, condensate face velocity, high-efficiency hoods, overhang, discharge location and grease ductwork) to confirm alongside the airflow result.
Print or save a record — Use Print / Save PDF to produce an A4 record of the inputs and results for the project file, or Export CSV to take the schedule into a spreadsheet. The layout reformats automatically for printing.
