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We have been paid by another mechanical engineering firm to review and ultimately stamp design drawings on project which is an Aminal Clinic. This building has a surgery room, isolation room, and special procedures.  I've worked on many hospitals, but never one with animals and the codes (IMC 2006) don't specifically address room types with animals. The way it was designed, is with residential single zone split systems integrated with an ERV for the outside air.  The issue that I am having is that I am tempted to treat the surgery and isolation rooms as I would one in a people hospital with HEPA filters and pressure monitoring, 25 Air Changes per hour for the surgery, etc but this would drastically change the original design concept and add cost. Since ultimately I will be stamping the drawings I want it done correctly without overdesigning it. Does anybody have any experience with Animal Hospitals and how to ventilate these types of rooms ?  Where can I find design guidelines for this type of building.

Thanks for your help.


You're on the right track. How does nosocomial disease treat animals any differently than humans? They're mammals, so are we.

If it looks like an hospital and smells like an hospital, it's an hospital.

That the Owner may not have budgeted for a hospital is a problem of his making, not yours.

I had state authorities tell me the same thing on an hospital in a prison: "It's only prisoners, don't worry." The principal in my firm insisted I do what they (state) told me to do: I resigned rather than compromise the Engineering.


Willard3 -

Excellent post!!  I read Mechanicaldude's post earlier and had the same thoughts.

Mechanicaldude -

I would treat it no different than if it were used for human medical treatment.  I was surprised to find ASHRAE Applications does not address this.

Andy W.


Thanks guys for your input.  I agree with you completely.  I didn't find any design guidelines or literature for this type of facility.  I do know that odor control is a big deal with this which is something that is not dealt with in human hospitals, but much beyond that if you know of any documentation that could be help please let me know.


The original design engineer should have met with the Owner to establish design criteria.

Just so you know, there are varying degrees for designing an HVAC system for animal surgery rooms.  For research laboratories (vivariums) the animals can be valued at 100's of thousands of dollars, so all systems (arch'l & HVAC) should be designed to maintain a high level of sterility.  Same goes for equine facilities taking care of racing throubreads.

In my opinion, for a general vet. clinic surgery room, HEPA filters, 25 ACPH, etc. is overkill.  You'll see that the doctors gowning procedures are very relaxed.  Also architecturally, these rooms don't have the finishes or layout (i.e. airlocks, scrub sinks outside) that are atypical of a human or vivarium surgerical room.  

Bottom line, you'll do dis-service to the Owner (spending his capital, delaying construction w/ budget overruns, etc)  unless you & the original designer understand his needs & requirements.  

Btw, I am fixing a fairly large Vet Hospital that has 25 tons worth of single zone CV DX split systems.  I would reccomend some type of zoning system no matter what what level of facility it is.


Guys - I changed my position - this is really talking off the cuff here - which I'm prone to do (as in above).... but I would think you would want something less than a surgical suite - but more than just a patient room at a local Doc in the Box.  But I think you could approach the design with "hospital" mentality  utilizing light commercial equipment - just adjust the recommended values.

Say you used residential splits for this as suggested.  Zone them - as flrfan suggested to Surgical suite, other animal holding area on another and the office (assuming there is an office area) on another.  Using an energy recovery unit (ERU) I think is a solid idea - though I might include some type of heating/cooling in it also to maintain a neutral 76 degree discharge.  I would let the ERU would maintain the desired negative pressures (I would start with 10 - 12 AC/HR)with the dx splits making up the difference with the supply air from the ERU.  I think I would employ a higher level of filtration like a electrostatic filter and maybe use some duct mounted ionizion generators to address odors. Bioclimatic makes some stuff that has worked well for me in the past.  You might consider a Nortec duct mounted humidifier also for the surgical suite for winter time.  The down side I see with this design is the owner would have to be made aware that thermostat would have to be set to the "On" position (all fan always running)and the ERU operates the same 24/7.  How long will that last? I guess night set-back would still be possible though.

Off the cuff reaction after some thought....  But money talks.....

Andy W.


I'd recommend looking at the AAALAC standards. While it is intended for research and laboratory, it includes good details for vivarium, feed rooms, feed room, operatory, pre-op and post op.

I think that going to 100% OA should be considered along with energy recovery, unless you want to HEPA returns. Definitely include VAV and setback, as you will probably be dealing with high ACH for certain areas, like the operatory suite. If not in use, yo can save a large amount of money on setback. Energy recovery off exhuast is challenging so how the ductwork is run is a major factor. Sick animals should be expected, as well as for potential for allergens for humans. Differential volume control should be included as you will need to include relative differential pressure in the operatory between pre-, post-, and operatory.

First and foremost, I'd find out what type of animals, and what size, the facility will treat. Size of animals should dictate ACH, as well as access within different areas. Review of equipment list is important, no just for connected load, but also as potential energy and first cost savings. For smaller animals, if needed to be isolated for sicknes/observation, microenvironments may cost money, byt are cheaper in the long run on O&M.

Definitely verify this would be mamals only. Room environment and ACH changes for different mammals, and is different for other animals.

You should be able to find aditional infor from the Department of Agriculture as well.



A good source for animal hospital is

"Design Starter Kit for Veterinary Hospitals"


AAHA (American Animal Hospital Association)




We have been paid by another mechanical engineering firm to review and ultimately stamp design drawings

This practice is termed 'plan stamping' and is illegal in the U.S. You as the P.E. must be in "responsible charge" of the engineering. It is good at least that you are trying to educate yourself on the subject.


mauricestoker, good post. Please also look up the "Guide for Care and Use of Laboratory Animals." This is a primary reference book for accreditors.

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