By Faz Ehsan
Changes in healthcare delivery models over the last decade, paired with the ongoing global health crisis, have required creative new approaches to the design of healthcare facilities.
With the passage of the Affordable Care Act, the healthcare industry saw a shift from traditional in-hospital treatment to a greater emphasis on wellness and prevention. This led healthcare systems and developers to expand their focus to include smaller, more nimble satellite facilities, such as outpatient care, and the adaptive reuse of existing structures not originally designed to meet the specific demands of the healthcare industry. This also sparked a great deal of interest in ‘speed to market’ construction and efficiencies associated with completing projects in tight timeframes.
The structural design of healthcare facilities must take into consideration a variety of factors. Oftentimes, new buildings and existing structures must be able to accommodate heavy medical equipment and other loads. There are also unique requirements for the facility itself, such as connectivity to adjacent buildings on the healthcare campus, phased occupancy and the need to minimize disruption to existing services and operations during construction. The following is a summary of structural considerations for the design of new facilities, adaptive reuse of existing structures, and potential approaches to incorporating flexibility into the structural design.
New Facility Design
Healthcare facilities typically include a variety of medical equipment for diagnostic and treatment purposes. An important consideration for healthcare projects today, whether in new or existing construction, is meeting vibration and shielding demands of medical equipment. The structural design of the facility must address the vibration criteria of sensitive floor-mounted equipment, secondary structures for ceiling-mounted equipment and loads and load paths for installation and future replacement of heavy medical equipment. Shielding requirements for imaging and radiation treatment including CT scanners, MRI. Linear Accelerators and Proton Therapy affect the structural design and need to be addressed per manufacturers’ requirements and specialty imaging consultants. Other operations within a hospital that can affect the vibration experienced within the facility include patient and material transport needs, including helipads and automated guided vehicles (AGV). Additionally, AGVs often require dedicated staging areas and elevators and impose increased floor levelness and flatness requirements on the structure. The structural engineer must work with the project team to address acoustic and vibration issues as well as the design for the loads imposed on the base building.
In addition, hospitals and facilities in urban centers must address noise generated by traffic on a busy street, underground or elevated train tracks as well as disruptions caused by the building occupants and equipment. This may require the isolation of foundations and sensitive equipment, stiffened floor structures, use of vibration damping materials or a combination of all these factors. Certain construction processes such as pile driving, or installation of sheeting, may cause undesirable sound and vibration for adjacent facilities. The structural design and selection of structural systems must anticipate these issues and take them into account.
HVAC and electrical demands are also important considerations. Because of the process-intensive nature of these facilities, and the fact that medicine is an around-the-clock operation, demands for cooling and power are usually greater than for other building types. The need for higher quality air, minimum air flow rates for contamination control and humidified environments lead to larger and heavier equipment as well more ducts and pipes competing for limited ceiling and shaft space. Dedicated mechanical floors for a large hospital may require a double height floor to accommodate stacked units and require secondary systems of catwalks and platforms to service the units.
It is critical to establish the facility’s structural system as early as possible in the design phase with a detailed plus-delta analysis. Material and structural system selection is determined by the facility’s unique requirements, geographic location and local construction practices, construction schedule, and timeframe. Many healthcare facilities utilize structural steel, concrete, or a combination of the two. Timber construction may be utilized in some scenarios depending on the function of the facility and anticipated services to be provided.
While functional and operational needs of a healthcare facility must always be addressed, additional considerations such as patient and family experience, patient safety, and integration of the facility with the community may also impact the structural design.
Adaptive reuse of structures not originally designed as healthcare facilities, such as retail, office buildings, and warehouses pose unique challenges for the project team. Some key structural- and construction-related questions that may factor into the decision-making process include:
- What was the original structure designed for, and what is the new proposed use of the facility? Identify original design loads and structural systems used.
- What is the suitability of the existing facility for adaptive re-use? Are the available floor-to-floor heights adequate? Does it meet acoustic and vibration considerations?
- What is the level of difficulty in upgrading the structure, if needed? Are there logistical issues, including site access, crane locations?
- Have there been building codes changes since the original construction that may impact proposed modifications? Would this result in a change in building occupancy, e.g., business to institutional? What are the implications?
- Are original design and construction documents available, or will detailed site surveys be required to establish structural capacity? This may impact cost and schedule.
- Are there operational constraints, such as maintaining functionality of the overall facility while a portion of the building is being upgraded? Does this create schedule constraints for construction?
Designing for Flexibility
The use of a healthcare facility often evolves over time depending on the specific and changing needs of the healthcare market. Demand for particular program elements, such as beds, operating rooms, and diagnostic or treatment spaces may vary over time. The ongoing COVID-19 pandemic, for instance, has demonstrated how hospitals must adapt quickly to meet the needs of a specific crisis. It is likely that the next pandemic will have a different set of health parameters that will need to be addressed. The capability of a healthcare facility to meet these ever-changing needs will be impacted the facility’s flexibility. This pandemic has also highlighted the need for temporary facilities that can be constructed quickly and efficiently to provide emergency treatment to a large number of patients. This has led to renewed interest in modular construction, in which modules are assembled off-site and transported/erected on-site. This method has been explored for the adaptive reuse of existing structures such as retail and warehouses. In certain cases, an existing structure may serve as a shell for the pre-fabricated modules to be assembled and inserted into these shells.
Here are several major considerations that should be taken into account when designing the structure of new and adaptable facilities:
- Selecting structural systems that can be locally modified or reinforced easily without major disruption to overall operations
- Load capacity – use of baseline live loads that may exceed code-prescribed minimum loads for some program areas to accommodate temporary surge conditions
- Creating open floor plans by locating vertical circulation, major mechanical shafts, etc. away from the center of the floor that will maximize flexibility in the event of a major event
- Selecting façade systems that may be locally removed and re-installed to allow specialized medical or other equipment to be transported directly into elevated floors of the facility
As the healthcare industry continues to evolve, and new global health challenges present themselves periodically, it is incumbent upon facility owners, design professionals and the construction industry to remain innovative and seek solutions to problems that are yet to be defined.
Faz Ehsan, Ph.D., P.E., is a Managing Principal with Thornton Tomasetti.