Go with the Flow: Midstream Design Changes

Long-term design and construction projects pose unique challenges beyond the simple matter of remembering why you designed something the way you did three years ago. For instance, building codes might be updated every two to four years. Moreover, in terms of hospital design, the codes may affect not just the building systems themselves, but also how these systems impact health and safety measur...


Long-term design and construction projects pose unique challenges beyond the simple matter of remembering why you designed something the way you did three years ago. For instance, building codes might be updated every two to four years. Moreover, in terms of hospital design, the codes may affect not just the building systems themselves, but also how these systems impact health and safety measures, such as infection control.

When the latest edition of the American Institute of Architects (AIA) Guidelines for Design and Construction of Hospital and Healthcare Facilities was issued in mid-2001, and subsequently adopted by the State of Maryland's Dept. of Health and Mental Hygiene, the multiple-addition Phase II construction project at Frederick Memorial Hospital, Frederick, Md., was well under way.

New guidelines, existing design

Even though it wasn't required to adapt the project to conform to the new guidelines, the hospital saw the opportunity to provide an enhanced environment for patients and staff. And the project architect, Noelker & Hull Associates, Chambersburg, Pa., took the lead in identifying the adjustments needed to meet the new requirements.

To minimize delays, the design and construction team reviewed possible impacts on the ongoing installation of systems and on the construction areas. Maintaining flexibility in the design of the M/E/P systems was essential, if not to accommodate code-related revisions, then certainly to allow the hospital to revise an area for different use or new equipment. Conscientious engineers may occasionally be accused of over-designing a system, but "gold-plating" isn't exactly how a facility director would describe it when he has the ability to connect two additional circuits at an electrical panel.

From an infection control standpoint, the new AIA guidelines most affected the existing system design of the emergency department waiting room and triage area. With minimal ductwork modifications and the addition of a dedicated exhaust fan, these rooms were re-designed to be fully exhausted. Since a greater quantity of exhaust air would require an increase in outside air, the associated air-handling unit was reviewed to ensure that the increase would not affect its cooling capacity. The unit had already been approved by submittal and released by the contractor for construction, so adjustments could have been difficult—possibly costly—and might have delayed equipment delivery. Fortunately, the unit's capacity was adequate for the new design.

The original architectural design had triage areas with control doors at the emergency department waiting room but open portals to the critical care suite. This arrangement allowed ready access for hospital staff, but it posed a problem for meeting a new guideline requiring the triage area to be under negative relative air pressure. As a result, the engineering requirement forced an architectural revision—to provide doors at these portals. The hospital also opted to use room-pressure monitors to ensure that the HVAC system effectively maintains negative pressure and provides an alarm when this protection is not functioning properly.

Actually, few other areas or systems required adjustments to conform to the new guidelines. In many respects, like many code updates, the guidelines reflected concerns that were already widely known and accepted within the health-care environment. Where practical, these issues were already addressed in the original design.

For example, the HVAC system demolition documents indicated that existing exhaust systems or temporary exhaust measures and pressure monitors were required to maintain a negative relative pressure between the construction area and adjoining occupied spaces. Maintaining this pressure differential is crucial, because debris and contaminants dislodged during construction can be hazardous, especially to the patients who are immuno-compromised or -suppressed.

In a process known as infection control risk assessment (ICRA), the design and construction team coordinated closely with the hospital staff to ensure the effective protection of susceptible patients. The more susceptible the patient population—i.e., patients with HIV/AIDS, other major diseases, or immuno-suppression from anti-rejection drugs for post-transplant recovery—or the more intensive the construction process, the more stringent the safeguards should be. During a multiphase project such as Frederick Memorial Hospital's ongoing renovation, the HVAC and architectural barriers had to be defined for each construction phase to allow for contractor implementation and monitoring.

Keeping domestic water safe

Another infection issue that has been addressed at FMH is domestic water contaminant control and enhanced air filtration in rooms for immuno-compromised patients. The domestic hot-water generation system has been upgraded from a steam-immersion heater and storage tank system to instantaneous steam-fired water heaters. The system was upgraded because storage tanks, during low water flow conditions, can provide an environment that assists in contaminant amplification.

Additionally, the gas-chlorination domestic water treatment system was replaced with a copper-silver ionization system that destroys microbial contaminants and provides a residual concentration. The hot water recirculation system is being rebalanced as each phase of construction is completed to ensure consistent water to and from all areas. Eventually, troublesome, older galvanized-pipe water mains will be replaced with new copper ones as these areas undergo renovation.

Protecting cancer patients

In the oncology patient rooms where patients commonly have reduced capability to ward off illness, the HVAC system is configured similarly to a protective environment room. The air from the central air-handling system is already filtered to 90% dust-spot efficiency and is delivered to a constant-air-volume terminal unit with reheat that allows independent temperature control by the patient. A high-efficiency particulate (HEPA) filter/diffuser delivers air to the patient room, and the room is monitored electronically to ensure a positive relative pressure with respect to the adjoining corridor. Alarms at the nurse station and via the building management system to the plant operations department will activate should this protection not function properly.

The best way to anticipate code changes and identify shifts in healthcare delivery is to be involved in the organizations that develop these codes: the American Society of Healthcare Engineering (ASHE), the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), and the AIA. Also, it is important to work closely with the hospital to understand how the engineering systems support their evolving medical service lines. Every hospital has different needs and is affected differently when new diagnostic equipment or medical procedures enter the marketplace.

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