ACH in hospital operating room

[odelgado]

Greetings everyone,

I know that ASHRAE Standard 170 dictates the ventilation and combination ACH for different type of rooms in healthcare facilities. I was wondering is there a way to reduce the combination ACH if the ventilation ACH are increased? I mean, if the room requires 20 combination ACH with 4 ventilation ACH, can the ACH be reduced to say 15 if they are 100% OA?

Thanks for your time, any help will be greatly appreciated.

 

[willard3]

I would check your state hospital code for this information if you are in the States.

 

[DRWeig]

Yes, as willard3 wrote, it depends on your local code.

Best to you,

Goober Dave

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[odelgado]

Thanks to both. We use ICC codes at the moment, but when the hospital was designed UBC 1997 was the valid code. The 2009 IMC only mentions 30 cfm/person for ventilation rates but makes no reference to ACH. I can't seem to find a digital copy of the UBC online.

 

[ChasBean1]

I don't think you can reduce the total ACH. If it's by all outdoor air the running costs might be big. This sounds like a good application for fan powered boxes with HEPA supply diffusers.

 

[cry22]

the code has a total ACH column and a Min OA ACH column? - Code is code, comply with it, period. You should not be speculating about it.
Some hospitals have their own requirements. Check with your architect medical planner, some doctors require a minimum of 65F in the room, meaning you need even higher ACH.

 

[Drazen]

your logic has its merits for general applications, but for operation rooms minumum "combination" ach serves to impose filtration intensity for all space air and therefore must not be reduced.

 

[urgross]

It makes for tougher control for relative differential pressure requirements.

The VA allows for decreased ACH during unoccupied periods, but maintaining the relative dP and being able to go to full operation for emergency service make it a challenge. Our ORN's are not fond of the idea, and I don't care to argue with an ORN about her own room. Even if it is allowable, are you sure you want to do it?