Choosing the Right Mechanical System for Health Care

By Jeff Harris, Director of Mechanical Engineering, Hammel, Green and Abrahamson, Inc., Minneapolis July 1, 2006

Studies have shown that the mechanical system is not only a major contributor to the comfort and satisfaction of a building’s users, but also to the owner’s bottom line in terms of operations and maintenance costs. Therefore, selecting the most appropriate mechanical system is crucial for health-care facility managers and a decision that should be based on an objective assessment of both system performance and financial criteria.

Often, decisions about a mechanical system for a new facility on a health-care campus are based on facility managers’ experience with a particular type of system and their assumptions about its appropriateness for the new facility. For example, they may initially expect to see a hospital-type mechanical system design that incorporates water-cooled chillers; high-pressure steam boilers with heat exchangers and the ability to distribute steam to the sterilizers; an emergency generator; and central domestic hot water storage. Yet this might not be the best system for, say, a new outpatient clinic.

Decisions are often based on the track record of systems that are already in place, despite their appropriateness for the new building. Many times decisions about the mechanical systems are made without any direct communication with the institution’s executive leadership and are based on a vague understanding of what is too expensive. What’s needed is a process that increases the likelihood that facility managers will be able to gain the understanding of the institution’s executive leadership—or at least get them to buy into it.

The matrix

A decision-making matrix is a valuable tool for evaluating the degree to which various alternatives meet the institution’s criteria for the mechanical system. It enables the owner to step back a bit from its assumptions and experiences to gain a perspective on a number of feasible technical alternatives.

Developing a matrix requires the building system user group, working with its engineering consultants, to identify appropriate criteria, assign a priority “weight factor” to each criterion and rate each alternative on the degree to which it meets each criterion.

Identifying the criteria should be the first step in the process—before development of alternate mechanical system designs—to help maintain objectivity. The idea is for the criteria to drive development of the alternatives, not the other way around. The user group should start by considering questions such as: What does the market demand? What is the business plan? Who are our patients? What service level do they expect? How does this project fit into the master plan? And so forth.

Common criteria for many health-care institutions are:

  • patient and staff safety and comfort

  • initial and life-cycle costs

  • future expansion, system flexibility

  • energy efficiency/payback

  • maintainability

Depending on the institution’s master plan and the specific project, flexibility for future expansion might be a high priority. For example, if an academic medical center is in an urban core and is building the first of a multi-phase building program, then flexibility should be an important criterion. However, if a community hospital in a rural area is building a replacement hospital with a projected life span of 20 years, then flexibility may be less of an issue. For many institutions, building aesthetics are another concern, while for others, sustainable design is a factor in the selection of a mechanical system, whether the project is aiming for LEED certification or simply using environmental sustainability as a design guideline.

Weight factors

Next, the building system user group/project team should assign a relative weight factor to each criterion depending on its level of priority as a portion of a total of 1.0. For example, a mechanical system’s effect on patient and staff comfort might represent 25% of the relative weight of the decision (.25), while aesthetics might represent 10% (0.10). The weight factor is a method to keep the first cost, which is always a big concern, from becoming the only factor in determining which system is most suitable.

The criteria and relative weight given to each decision factor serve as a guideline for the mechanical engineers to develop several alternative schematic designs, a baseline budget estimate and construction estimates of each design. This is important: bringing an experienced health-care construction management firm on board at the planning stage ensures that the building user group/project team will be working with accurate estimates.

When the user group/project team reassemble, they will rate each alternative based on the set of criteria, assigning a score from 1.0 to 4.0 to each alternative based on their assessment of how well it meets each criterion, with 1.0 being worst and 4.0 being best. For example, rooftop units might only earn a score of 1.0 for patient and staff comfort, yet this type of system might earn a top score of 4.0 for its low initial cost. In contrast, a system installed in an excavated basement might earn a top score of 4.0 for the fact that it will not interfere with future vertical expansion of the building, but it might earn a relatively low score of 2.0 for initial cost. The weighted points of each option are totaled for a weighted score. (See Fairview Health Services Proves the Value of “the Matrix” .)

The group should also discuss the pros and cons of each alternative. For example, perhaps the building user group cites low initial cost as the main advantage of rooftop units, while the disadvantages include more time-consuming maintenance due to lack of accessibility; potential noise and vibration issues; and the system’s vulnerability to the effects of weather. The pros and cons should then be tallied for a total unweighted score. In addition, the group should use the construction estimates to gauge the relative increase or decrease in cost as compared to the baseline budget estimate.

Worth the effort?

Facility managers may wonder if this process and the results it produces are truly worth the effort of developing the matrix and scoring the alternatives. While it does require planning and scheduling—and enforcing attendance of at least one lengthy meeting of staff and leadership who normally don’t interface with building mechanical systems—the payoff is that the project team can make a decision that is fully supported. This helps reduce the urge to revisit decisions later in the project unless the priorities for the project change, because the decision is understood to reflect those priorities. On a personal level, the decision-makers are also invested in the earlier decision and are less likely to want to go backward.

When it comes time for a final selection of a technical alternative, it is valuable to include executive-level decision-makers from the facility as well as from the architecture firm. This greatly reduces the challenge facility managers often face of gaining acceptance for a particular decision, particularly if it represents an innovation.

Ultimately, use of this objective process and tool provides decision-makers with a higher comfort level because they will know they have selected a system that meets the performance and financial criteria that are important to their institution.