Ventilation for an office with no windows

[jimmer]

I'm just about to start and wire a load of refurbished industrial units which have offices at the back but no natural ventilation. Aparently you need 10 l/s per person per office of extraction. The problem is i have to allow fresh air to replenish the used air, but the only place for inlet / outlet grills to the out side are about 2 meters above the office ceiling so a air brick at low level is not possible. Has anyone else come accross this type of problem and is there some king of dual unit fan that extracts and replaces the air.
Any help much appreciated.

 

[ninjadeathstalk]

You don't need a dual unit fan that extracts and replaces the air. An extractor fan would do this if the airflow is powerful enough. You'll just need to put the extractor in backwards. It will then push air into the room rather than pulling it out, so you'll get clean air for the office. If you mount it in the usual way it will draw the air from the industrial unit into the office.

1 litre/s = 0.001 meters³/s
10 litres/s = 0.01 meters³/s

per hour (multiply by 3600):
36000 litres/hour = 36 metres³/hour

A 4" toilet extractor fan will push 85 m³ into the office, which would be ok for an office of 2 people. Ventilation & Cooling - Extractor Fans, Desk Fans and Air Conditioning

A 4" Manrose MRK In-Line Centrifugal Duct Fans is capable of 180m3/hr 50 litres per second. Enough for 5 people in the office (which I would guess is plenty for any industrial unit), but is a little more expensive. 100mm Inline Centrifugal Extractor Fan

I would mount them outside the office due to noise (or else it will be like sitting in a toilet) and use ducting to vent to the atmosphere. Don't forget about vibration if you mount them directly on the office roof.

I am not an expert, but I hope this helps. I am sure somebody else with more expertise will be able to help further.