By Greg Lavriha, PE
What can be done when patient rooms need to be renovated, but they currently rely on fan coil units (FCUs) or PTAC units for space conditioning? Doesn’t ASHRAE Standard 170 now prohibit using these in patient rooms?
For patient rooms, the code used to allow fan coil units and PTAC units in patient rooms for heating, cooling, and fresh air. You’ll see this commonly in hospitals built in the 1950s and 60s.
(A side note as we get started: In ASHRAE Standard 170, we find FCUs and PTAC units referred to collectively as “recirculating room units” (RRU). I’ll use that term through the rest of the article.)
Today, the code has changed, which has brought some confusion. One common misunderstanding: that Standard 170 strictly prohibits the use of RRUs in patient rooms.
In fact, RRUs are still an option for select spaces in healthcare facilities, including patient rooms. The key is that the code does not allow RRUs to be used for bringing fresh air into patient rooms. Instead, fresh air needs to be delivered via ductwork and an air handling unit (AHU).
Table 7.1 of Standard 170 explains what spaces are allowed to have RRUs. In the case of patient rooms, there are two basic ways to renovate the HVAC to bring it up to code.
Continue using the fan coil units, but for heating and cooling only. Use AHUs and ductwork to bring filtered and conditioned fresh air into patient rooms.
this scenario, the RRU’s outside opening is sealed. Ductwork is run down the corridors to the patient rooms from an AHU, which brings in filtered and conditioned fresh air. The ducts are generally very small, just large enough to provide the fresh air.
This is typically the cleanest, simplest option. In a hospital with limited floor-to-floor space, it might also be the only practical option.
This solution is appropriate for regular inpatient rooms. It can’t be used for ICU, PACU, or NICU rooms, though, because the RRU requires maintenance, which can become a source of infection for susceptible patients.
With this option, the RRU is removed entirely. Fresh air and space conditioning are brought into the patient room via ductwork. Return air ductwork is also added. A reheat coil is required to provide temperature control and maintain the minimum air change rate.
For this option, the ductwork is significantly larger, requiring much more space for installation.
A third option, if the existing rooms are no longer needed for patient beds, is to convert them into administrative spaces, such as physician offices or medical records storage.
As an administrative space, ASHRAE 170 would no longer apply. In that scenario, RRUs can continue to be used for both fresh air and space conditioning.
A perennial challenge for hospital renovations is incorporating new code requirements. The design of older buildings isn’t always conducive to the demands of today’s codes and standards. With ASHRAE Standard 170, healthcare organizations will find they have options as they pursue patient room renovations.
Greg Lavriha, PE, specializes in healthcare and research facility engineering. His design work supports disease prevention and patient wellbeing. Greg serves on the board of NOSHE (Northern Ohio Society for Healthcare Engineering) and the International Code Council’s International Mechanical Code (IMC) Code Development Committee (2015-2017). He is a member of ASHE.
Greg presented “Maintain the Clean: A Practical Guide to ASHRAE Standard 170 Air Pressure Requirements" at the 2015 Midwest Healthcare Engineering Conference and Trade Show.
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