Healthcare Outdoor Air Requirements??

[anothernewbie]

My company has just gotten a project designing MEP for an ambulatory surgical facility. I am doing the schematic design and trying to figure out preliminary RTU sizes. I have found recommendations that call for 100% OA for units serving surgical suites, but nothing in the code that mandates other than cfm/person. Does anyone have any advice or maybe point me in the right direction? My preliminary sizes have been based on 25 ACH (maximum) for operating rooms and 8 ACH for pre/post opp areas. This is resulting in very large sizes. Around 2 sf/ton....Any suggestions will be appreciated!!

Thanks,

SR

 

[imok2]

Some guidelines:

http://tristate.apogee.net/cool/csch.asp

 

[walkes]

You may try looking at the AIA Guideline for the Design and Construction of Hospitals and Healthcare Facilities.

http://www.aia.org/aah_gd_hospcons

There is also a Green Guide for Healthcare with a downloadable reference manual.

http://www.gghc.org/

 

[ChasBean1]

You mean 2 cfm per square foot? 2 sf/ton might need its own power plant.

100% OA systems aren't needed. You can return air or use an enthalpy wheel system. You just need to be careful with exhausting air where needed, and keeping your minimum OA high enough to offset exhaust and high enough to meet OA ACH requirements. AIA says 3 ACH OA, 15 ACH total for ORs and 2 ACH OA, 6 ACH total for recovery rooms (this is 1997 AIA - note there may be a newer one).

-CB

 

[anothernewbie]

Thanks for your replies. I appreciate the comments and advice. Yeah, 2sf/ton is pretty high, huge actually. I'm not really sure what I was thinking about when I wrote that. Hopefully I can offer some assistance in the future. Thanks again,

SR

 

[cme]

Where is this project located?

Rule of thumb is 30% OSA, 3cfm/sf (this can vary on #OR's), 225 cfm/ton, 90 btu/sf heating

farr 30/30 prefiletrs and 95% cartridge final filters

You have to get the temp and RH conditions from the head of the surgical staff (DR, nurse and anasthesiologist). They are going to tell you some rediculous condition like 50 deg F, 60% RH. There is no possible way to get 60% RH at 50 deg F, you are dehumidifying and humidifying simultaneously.

Current AIA guidelines say 15 AC total air. They used to be 20 and I did many at 25 ACH. That was the office standard.

Use CV reheat boxes with LAT at 105, they're all 2 row coils, 40 deg WTD.

FARR 3P glidepak final filter bank

Low returns in 2 locations in the OR's.

75 cfm differential per room needing pressure control

This is definately a blow-thru configuration, 48 deg lat.

Figure on a 35' long air handler ..... humidifier has to be 15' upstream of the final filter bank

Use Anemostat Multi-Vent diffusers in the OR, design to NC20-25 max

NO DUCT LINER IN DUCTWORK, AHU'S AND CV REHEAT BOXES!

 

[cme]

BTW, some surgeons want HEPA final filters, so that twists things a bit