The highs and lows of hospital heights
Single- and multistory buildings have their pros and cons. Do you know which design is generally the best?
A reader question came up regarding the viability of multistory hospitals. Given a choice, is it better for a clinic to be on a single floor or on multiple levels?
Practice owners, of course, have nowhere to go but up in some instances. Think small sites and locations in dense urban areas where ground floors aren’t big enough. My firm is working on an 80,300-square-foot hospital in India that is situated on less than an acre. The building is seven stories tall!
Where the choice exists, though, is taller better? Like many questions related to design, the answer is, it depends.
A common thought is that a smaller footprint allows for a smaller foundation and roof area, making the building less expensive. For some buildings, like houses, this often is true. And it certainly is true for large-scale, redundant floor-plan buildings such as apartments and office high-rises. When talking about animal hospitals, it’s not so clear-cut.
Gross Square Footage vs. Net
Whenever more than one floor is involved, we need to factor in the requirements for vertical circulation, or the movement of people from one level to another. Depending on the building’s size and use, you might need one or two exit stairways. Similarly, you might need an elevator. Those building features might not sound like much, but the dedicated space can add significantly to the size and cost of a structure.
When my firm designs any project, we start with a building program — a list of needed spaces, their attributes and where they ideally would be located. This document becomes the basis of the design. The total sizes of these rooms is the net square footage.
A measure of a building’s space efficiency is the net-to-gross square footage. Reasonably efficient hospitals will have a 25 percent “grossing factor.” That is the non-programmed areas for things like wall thicknesses, hallways and circulation, and incidental space. These will add 25 percent to the net square footage. A 6,400-net-square-foot hospital, for example, has 8,000 gross square feet.
So, what effect would this math have on a two-floor plan compared with a single story? Excluding vertical circulation, we would have two floors of 4,000 square feet each. Because of the building’s size, we would need two egress stairways and an elevator. Assuming a 12-foot floor-to-floor height, the stairs would take an additional 850 to 1,100 square feet. The smaller number assumes minimal size while the larger one provides enough width for functional second-floor clinical use. An elevator compliant with the American With Disabilities Act would add another 250 square feet. Add in vertical circulation and our grossing factor has gone from
25 percent to as much as 40 percent! Not very efficient at all.
As for cost savings, yes, we cut the roof and foundation areas in half. Offsetting that is the structural system for the added 4,000-square-foot second level, so the savings are not as large as one might guess. Between offsetting costs and increased gross size, building skyward is rarely less expensive.
Know Your Labor Costs
Factors beyond construction costs need to be considered. In addition to intelligent space utilization, modern hospital design focuses on staff efficiency. The single biggest expense over a building’s 30-year functional lifespan is not the initial construction but the staffing. Construction averages about 10 percent of the 30-year total while personnel represents about 40 percent. Putting the greatest effort into leveraging your most expensive asset makes sense.
How do you do that? By focusing on staff efficiency.
A rule of thumb says that for a person of average fitness, 50 to 60 feet of horizontal travel takes the same perceived effort and time as climbing one flight of stairs. If a staff member’s duties can be contained within a 50-foot path of travel, remaining on one floor would be more efficient than making the person regularly negotiate stairs. Of course, the scenario changes a bit when an elevator is included. Then the limiting factor becomes lift wait times.
Working with hundreds of practices over the years, my firm has found that, when possible, keeping all clinical functions on the ground floor is best. This observation usually relates to hospitals at the smaller end of the spectrum — about 10,000 square feet or less. If conditions are such that the entire program cannot fit on the lower level, some administrative spaces work reasonably well upstairs: management offices, phone reception, the breakroom, an IT closet, storage areas, and heating, ventilation and air conditioning equipment, for example.
Keep in mind that if the upper level holds a unique space that a staff member needs for her duties or is entitled to, like a break room, an ADA-compliant vertical access likely would be required. You cannot intentionally construct a building that would prohibit hiring a disabled person or keep her from doing her job.
Larger projects might need to have clinical spaces on multiple floors. In those cases, an elevator is certainly necessary. I try to limit client access to the ground floor, primarily the entry and reception areas, the waiting room, and exam rooms. Client elevator access becomes a non-issue this way, and the elevator can be located in a spot dedicated to staff and patient use.
After that, laying out a large hospital depends on the service mix. Large equipment rooms can be very expensive to place above ground level. MRI and CT machines and linear accelerators are heavy. Placing them on the second floor or higher creates a number of other expensive problems.
Know Your Limits
To the greatest extent possible, my firm tries to eliminate redundancies. If the main treatment room is on the ground floor but the surgery suite is upstairs, you might need an X-ray unit on both floors.
Beyond the cost of added equipment is the probability of more staffing. Like the building, the cost of equipment operators eclipses the equipment expense. In larger specialty or referral hospitals that house separate departments, extra staffing might not be a problem, but we find that centralized support services tend to increase a building’s utilization and reduce its size.
Occasionally, a practice owner requests multiple stories to improve the building’s street presence and create a more noticeable landmark. A taller building contributes to that feel, but there are other ways to achieve the effect. One needs to check local zoning constraints, but a building’s exterior massing can be quite impressive and even appear to conceal multiple stories without the challenges and expense of adding floors.
With the occasional exception of incidental second-story space, like a pitched roof attic, all in all the preference is to construct a single story whenever possible.
Constructive Criticism columnist Paul Gladysz is the principal architect at BDA Architecture. The Albuquerque, New Mexico, firm specializes in the planning, design and construction of animal care facilities.