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Roughly how much outdoor air should that space get?
A ballpark figure from floor area and occupancy, using the typical published rates for each kind of space — so you can compare it with what the equipment is actually set to deliver.
The check
An estimate for conversation, not a design or a compliance calculation. The ventilation standard, the mechanical code and your authority having jurisdiction decide what a space must have — and a real calculation accounts for system efficiency, air distribution and the rest of the building. It runs in your browser and nothing is sent anywhere.
Ballpark outdoor air
180 CFM about 15 CFM per person at that occupancyA figure this size is usually within what a single packaged unit can supply through its minimum outdoor air position — if that position is set correctly and the damper still moves.
- Have the minimum position measured rather than assumed. Factory defaults rarely match a real space.
- Check the damper and actuator physically; seized linkages are common and invisible from inside.
- If the room feels stuffy at this figure, the problem is more likely distribution than quantity.
This is the range where minimum positions are often set too low, because nobody rechecked them after the space changed use or filled up.
- Measure what is actually being delivered with the system in occupied mode.
- Consider demand-controlled ventilation if occupancy swings — it ventilates for the people present rather than for the worst case all day.
- Watch the heating bill argument: more outdoor air costs energy, which is why economisers and recovery exist.
At this level ventilation is a system in its own right rather than a damper setting. It also becomes one of the larger loads in the building.
- Look at whether a dedicated outdoor air unit, with recovery, makes more sense than pushing it through the existing equipment.
- Demand control is worth real money here, provided the sensors are calibrated and someone checks them.
- Make sure the building can exhaust what it brings in — supply without a path out becomes a pressure problem.
What this is not: a compliance figure. If you need a number for a permit, a change of use or a dispute, that comes from the applicable ventilation standard and your jurisdiction, calculated from the drawings — not from a slider on a website.
Four reasons buildings end up under-ventilated
- The space changedAn office becomes a training room, a stockroom becomes a workshop, and nobody revisits the ventilation.
- Somebody closed itMinimum positions get reduced during a cold snap or a bill review, and never get put back.
- The damper stopped movingActuators fail and linkages seize. The building still heats and cools, so nothing prompts a call.
- Sensors driftCO2 and enthalpy sensors lose accuracy over years. Unchecked, they are guesses controlling real equipment.
