Work out the outdoor (fresh) air rate a space needs, taking the higher of the per-person and per-floor-area requirements — a planning aid to AS 1668.2.
Indicative only. AS 1668.2 sets specific outdoor-air rates and methods by space type and occupancy — confirm the correct rates for your project.
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Start free trialRequired outdoor air is worked out both per person and per square metre of floor, because either occupancy or the space itself can drive the requirement.
The governing fresh-air rate is the larger of the two — enough to satisfy both the people in the space and its floor area.
That outdoor-air rate, in L/s or m³/h, is what the ventilation system must supply to keep air quality acceptable.
It depends on the use and occupancy. Ventilation standards such as AS 1668.2 set minimum outdoor-air rates, often expressed per person (commonly around 10 L/s per person for offices and similar spaces) and sometimes per square metre of floor. This tool takes the higher of the two.
Ventilation here means the outdoor (fresh) air supplied to keep air quality acceptable. Air changes per hour count total air movement, which can include recirculated air. A space can have a high air-change rate but still need a specific amount of genuine fresh air — see our air change calculator for the other side.
Fresh outdoor air dilutes carbon dioxide, odours, moisture and pollutants that build up when people occupy a space. Too little ventilation leads to stuffiness, drowsiness and poor indoor air quality; the standards set minimums to avoid that.
No — it’s an indicative aid. AS 1668.2 sets the specific rates and calculation methods for each space type, and mechanical ventilation must be designed to it by a competent HVAC professional.
This calculator is an indicative aid using typical outdoor-air rates. Required ventilation rates and methods are set by AS 1668.2 and depend on the space type and occupancy. Confirm the rates and design with a competent HVAC professional.
traqR keeps mechanical ventilation jobs, designs and service records against each site. Try it free for 14 days.