Implementing Health-Protective Features in Buildings: Practical Actions—Case Studies
E. Sarah Slaughter
MOCA Systems (Management of Construction Activities) uses proprietary technology to rapidly produce fully integrated project cost estimates and construction schedules. The heart of the MOCA technology is its MOCABuildTM software, a dynamic microsimulation system that models the performance of work on a construction site, literally building the facility in the computer before it has to be built on-site. The system’s database incorporates specific construction activities derived from about 65,000 hours of time and motion studies on construction projects; the activities of every worker on each physical component have been identified and tied to the resources and time required to perform them (see Figure 6.1).
As a result, an owner, architect, or general contractor can weigh design and construction options, benchmark performance expectations, and identify and correct problems that otherwise would remain undiscovered. MOCA provides the data needed by management to make decisions that are both correct and timely: cost estimates, material quantities, construction durations, and detailed construction schedules and staffing requirements for each subcontract. It typically takes about one hour to run a simulation for these construction projects, and several simulations can run simultaneously, producing results for multiple scenarios to the owner and its project team overnight.
One significant problem that has surfaced in working with clients over the past four years, particularly in terms of implementing new systems and practices, is uncertainty. In particular, how much is it actually going to cost to include certain elements, including those that might be health protective? How can the information just learned be used in the next project? MOCA has proved to be very effective in reducing that uncertainty to acceptable levels.
This presentation focuses on five case studies that illustrate how MOCA was used to analyze the impacts on costs and time of changes to specific projects that incorporate health-protective design elements. The elements include interior partitions, exterior enclosures, service systems, and the structure in four building types: federal courthouse and office building, a large high school, office buildings, and a high-rise residential building.
FEDERAL COURTHOUSE AND OFFICE BUILDING
Following the bombing of the Alfred P. Murrah Federal Building in Oklahoma City in 1995, a number of approaches were developed to increase the safety of the occupants of buildings in the event of future attacks. One of the suggestions that emerged to significantly diminish harm from projectiles in either a natural or man-made
disaster was to use a double layer of sheet rock on each side of interior partitions. In addition to increased safety from projectiles, improved sound attenuation is provided.
We studied the effects of building a new courthouse and office building with a double layer of sheet rock and found that the estimated cost increase was less than 1 percent for both labor and materials with essentially no impact on schedule.
RENOVATION AND ADDITION TO AN EXISTING HIGH SCHOOL
The next example is a major renovation and addition to a high school that would be occupied during construction. The renovation was to proceed in sections, and the designer has specified concrete masonry units (CMUs) for the interior partitions. This is not unusual since many existing schools have CMU block, but this material also tends to increase noise and echoing, particularly in hallways. The alternative was to substitute interior drywall partitions for the CMUs to attenuate sound.
Two other findings emerged from this project. First, when compared to drywall, CMUs are problematic for phased construction projects where design changes are inevitable. If a change is required, the CMUs have to be taken out with a jackhammer. The drywall is much easier to remove, and its removal entails less dust and noise. Also, in Massachusetts, where skilled labor is very expensive, eliminating CMU partitions (and the cost of masons) for this specific project had a tremendous impact on reducing costs—32 percent for the interior walls subcontract, 4 percent for related electrical work, and 2 percent for the overall project cost. This was accomplished with no overall impact on the project schedule. An additional benefit of saving this much on a public project (where all funding will be spent) was that these funds could then be available for other desirable building features, potentially including health-protective features that might not otherwise be incorporated.
The owners of this building wanted to obtain a platinum rating under the LEED™ (Leadership in Energy and Environmental Design) rating system of the U.S. Green Building Council. This project incorporated active shade mechanisms on all windows to track the movements of the sun and adjust window shades accordingly. This system decreases glare and increases the level of natural light that is reflected into the building while reducing the heat gain from the windows. However, oftentimes when new technologies are proposed with which the contractors are not familiar, rather arbitrary premiums are placed on their installation in the specialty contractor bid. The owners were incorporating so many new features in this project that they could not afford to pay a premium for every element, so the task was to help them realize their goal of incorporating sustainability technologies while decreasing the perception of risk to the subcontractors, the contractors, and even the financing institution.
A very simple flow diagram was developed that showed how tasks were to be performed, and a simulation was run showing the flow of work in the work zones on one floor and the flow from floor to floor. The specialty contractor and superintendent were then able to visualize the feasibility of the installation and buy into the process. The cost and schedule impact was less than 1 percent for the shades and related electrical work and much less than 1 percent for the building overall (see Figure 6.2).
In a related activity, the feasibility of designing for a 100-year facility life was analyzed. The question was basically: “How do you design a building to accommodate all the changes that will be necessary over the span of a century?” One of the recurring issues in major renovations is what to do with the fire protection system when the interior partitions are moved. The typical approach is to shut down and drain the system, cut the pipe, move the partitions, and then reverse the process. Needless to say, this is a costly process that greatly increases the facility’s downtime.
There is a fully tested and rated system available that consists of a flexible hose that goes from the main branch element to the fire protection sprinkler head, so contractors can move it without having to turn off the system. One model uses gaskets that integrate into the ceiling grid and is particularly appropriate for surgery suites, clean rooms, and other areas where the penetrations between the plenum ceiling area and the room underneath must be minimal.
In this project the installation time for the fire protection system was reduced by 27 percent, and the total cost of the project was reduced by 2 percent. However, the real savings was that, when combined with other activities, the total time required for alterations decreased by over 10 percent. That means that other projects could potentially be completed one to four months sooner, which can be a significant benefit for many clients. A system such as this could not only be beneficial to the health and safety of occupants but could also have positive economic benefits for the owner.
This project in Puerto Rico needed to account for both seismic and hurricane loads and utilized a special steel frame with full moment beam-to-column welded connections. The option examined employed a column tree, which consists of beams stubs prewelded to the column, and in the field the beam is bolted to the beam stub. This reduces the need for welding on-site, produces higher-quality welds, and significantly reduces the exposure of workers to hazardous on-site welding conditions. In this case, the chosen assembly decreased the cost of the steel by 5 percent and reduced the amount of iron worker labor on-site by 50 percent (see Figure 6.3). Construction time was decreased by 13 percent for the steel erection and by 8 percent for the overall project.
However, this option can have significantly different impacts on steel erection cost and duration for other structural configurations. A similar analysis of steel column trees in Boston showed an increase in cost of approximately 1 percent, which indicates that the potential savings from prefabrication of these elements are very site and resource specific.
BUILDING PROGRAM APPROACHES FOR IMPLEMENTING HEALTH-PROTECTIVE FEATURES
There are several proven approaches for incorporating desirable features across a wide range of buildings quickly and effectively that could readily apply to many of the health-protective features discussed at the workshop. The first is the platform design approach, which uses a standard building core and shell that are adapted with certain features such as the air ventilation system, operable windows, or other key elements. Hotels, office buildings, and other production developers frequently make use of this system. It separates the performance and the design from the different elements and is similar to the way that cars are now designed.
In contrast, the engineering systems approach is much more effective when dealing with complex, technology-sensitive, high-performance buildings, such as research and development facilities, laboratories, and so forth. In these cases, there are families of systems where the interdependencies between the elements are absolutely critical. They often require very advanced performance simulation in such areas as airflow, electrical load, and myriad other factors.
The third approach is the building library, which works well for hospitals and universities that have campuses composed of a variety of building types some of which may be brand-new while others are hundreds of years old. Despite great differences in the building shell, these facilities often have a standard room type (e.g., classroom or surgical suite), and clients want to know the cost to incorporate certain common elements or features into their existing facilities. These room definitions can be stored in a system library for easy reference as future needs arise.
If decision makers in both the public and the private sectors are to be convinced that they should incorporate health-protective features in buildings, they must understand what it is they are being asked to do. A clear detailed definition of each alternative must be provided. Clear criteria to distinguish the differences among these alternatives before making a selection are required. Methods for calculating the impact of a specific element or project and for measuring and monitoring its effectiveness should be in place. Finally, there should be an established method or procedures for comparing and disseminating the results of various projects.
ABOUT THE PRESENTER
E. Sarah Slaughter, Ph.D. is the president and chief executive officer of MOCA Systems, Inc., as well as the developer of MOCA’s core technology. Before founding MOCA in 1999, she was a professor in the Department of Civil and Environmental Engineering at the Massachusetts Institute of Technology (MIT) specializing in Construction Management. She has researched innovations in design and construction for 15 years and has published more than 50 articles and books on this topic. Dr. Slaughter is a recognized leader in her field, and has been selected for several prominent committees and awards. She received all of her degrees from MIT, including a B.S. in Civil Engineering, an M.S. in Civil Engineering and Technology and Policy, and a Ph.D. in Civil Engineering and Management Science.