Hospital HVAC design questions

[Waramanga]

Hi all,
can anyone recommend a good source of information on design of hospital HVAC systems, ie operating theaters, sterile rooms, recovery rooms.

Also, in your opinion is a DX system able to be adapted to an operating theatre? I was thinking along the lines of DX unit to treat recycle air (50%) and OA treatment unit, exhaust fan for OA on VSD for pressure control.
The question is how to achieve humidity control with this setup?

Thanks for your thoughts.

 

[mauricestoker]

I'd recommend ASHRAE 170. The ASHRAE HVAC Design Manual for Hospitals has a good appendix specifically for OR.

I think you'll be looking at a lot of OA, so depending on your location humidity control could be a major utilities factor. Dessicant supply might be of use, as in many cases OR's will not allow latent recovery, only sensible.

A DX is ideally suited for humidity control, as not all central plants will be delivering water around 42*F for humidity knockdown.

 

[cdxx139]

Check your local codes. We have a local Dept of Public Health that has the requirements, but also takes most info from the 2006 AIA Guidelines for Design and Construction of Health Care Facilities.

What I do is get the cfm from the four code requried places:
1. Ventilation requirements of IMC
2. Loads of space
3. AIA requirements
4. DPH requirements

Whichever number is greater, I design around, that way I cover all applicable requirements.

Goood luck

knowledge is power

 

[AbbyNormal]

Search around on the VA site

The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install

 

[mauricestoker]

The VA is pretty much adopting ASHRAE 170.

 

[AbbyNormal]

VA info is free

The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install

 

[cdxx139]

and they have (had?) excellent details, especially on room pressurization etc.

knowledge is power

 

[mauricestoker]

I don't think you want to use their details. I'm not real keen on their specifications, either.

Look under the VA HVAC Design Manual, chapter 6. Note that VA does not allow any latent heat recovery. Standard has changed from 15 ACH OA to allowing ASHRAE 170 usage.

VA requires continuous monitoring, so if going that route I'd recommend pressure independent air control valves and continuous dP recording. Unoccupied setback is allowed.

 

[Waramanga]

Thank you all for you replies.
We dont have any issues with humidity here in general but like any location we can get 34deg C then a storm after to make humidity hit the roof. we also can get extremely low humdity at times. I think we will need some RH control but it wont be active frequently.
Also, i have seen a number of schemes for introduction of air into the theater but the one that seems to make the most sense is a terminal HEPA filter above the operating table. Can you acheive the required ACH with such a unit and maintain a reasonably low air flow?

 

[AbbyNormal]

you want the HORD system, an air curtain around the work area and a couple laminar flow HEPAs over the table

Low returns/exhausts minimum 2 kiddie corner

Try a site like EH Price



The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install

 

[sridhar1312]

ASHRAE has as of now free down-loadable HVAC design manual of Small Hospitals upto 90000 Sq.Feet. for all ASHRAE Members /Non Members.

Normally for operation theaters DX and chilled water system are no issues.
Ideally the supply air is with terminal filters and return taken through risers so that laminar flow is maintained.
You may incorporate Indirect heat recovery with Heat Pipes for recovering the heat from exhaust to prevent contamination.

 

[Zesti]

This thread might also be of interest:

http://www.eng-tips.com/viewthread.cfm?qid=235692