Journal of Architectural Engineering

Models of occupant flow in buildings represent powerful tools for improving safety and efficiency of occupant movements in large public buildings. The ability to predict the movement of people is valuable from the view point of safety considerations as well as several nonemergency aspects such as the level of service, efficiency and comfort, as well as space cognition and interaction. Capturing the manner of occupant movement can be used for the design of pathways and corridors in large public buildings such as train stations, airports, academic buildings, and shopping centers. Surprisingly, to date there has been very limited research on correlating the design of the building corridors to the occupant flow. Short of code requirements for emergency egress, there are very few guidelines on sizing and designing corridors. This paper presents the findings of a study aimed at developing a method to evaluate the flow of occupants in corridors, so that designers can understand how well a particular corridor accommodates the occupants’ movements and activities. In this paper, a queuing model is developed for determining the occupant flow density in corridors. The queuing model can be used to determine the occupant flow density in a wide array of corridor layouts and designs and correlate it to the level of service. In addition, actual data were collected and analyzed to validate the results from the queuing model. It is shown that the model is robust and accurate enough to model a wide array of design variables. The analysis can be very useful in designing efficient corridors in buildings of various scales ranging from small shopping centers to large airports, resulting in potential construction cost savings. A computerized model is developed and presented along with an example.

Water seepage into interior spaces and the resultant staining of wall and/or ceiling surfaces is a common problem with eave ice dams. If the outdoor temperature is below freezing, the roof is poorly insulated, and if the roof snow layer is thick enough, the temperature at the bottom of the snow will be at freezing. A portion of the thermal energy goes into melting some of the roof snow, that is, meltwater is generated which flows downslope toward the eaves. Some of the meltwater refreezes at the cold eave, forming an ice dam. The potential for water seepage is related to the horizontal extent of the ice dam. Mitigation usually involves placing an impermeable “ice and snow guard” layer for some distance from the eave. This paper presents information on the horizontal extent of expected eave ice dams with various returns period for 15 U.S. cities. In addition a correlation between ice dam size and the 50-year ground snow load is presented which allows one to estimate ice dam size for any U.S. city.

Currently, the ASTM design methodology to determine the load resistance of annealed window glass incorporates a probability distribution to model glass load resistance. A probability of 8 lites per 1,000 broken at the first occurrence of the design load was selected to match a load resistance consistent with a historical design factor of 2.5. The historical use of a factor relationship leads to the misconception that the design methodology follows an allowable stress procedure. The misconception has led to another common misconception among architects and engineers that a constant maximum principal stress exists, associated with the load resistance for any combination of lite thickness, aspect ratio, and surface area. This paper presents the relationship between the maximum principal stress in glass lites associated with their design loads for a probability of breakage of 8 lites per 1,000. The relationship clearly shows that the maximum principal stress is not constant for a single lite thickness for varying rectangular dimensions much less for all lite geometry combinations. A series of charts illustrates the trends in magnitude and location of the maximum principal stress as a function of lite thickness, aspect ratio, and surface area.

The roofing industry in the United States generates annual revenues in excess of $23 billion. This represents a significant annual investment in infrastructure maintenance cost and the opportunity cost of these resources can significantly detract from an owner’s ability to invest in other areas. In addition, a failed or failing roof system represents a heightened opportunity for failure in the building envelope and inherently increases the risk of additional costs. Present roof asset management practice typically bases replacement decisions on fixed intervals, inspection results, maintenance issues, and, occasionally, failure risk. This paper develops a model for evaluating occupant costs and considering their impact in the roof management decision process through a total life-cycle cost (LCC) model that includes user/occupant cost model and correlates minimum total cost with improved intervention points in the asset deterioration cycle. The model is estimated from and applied to the extensive roof systems at Carnegie Mellon University in Pittsburgh, Pa. For these roofs, we find that the least cost roof service lives are roughly 30 years, but there can be considerable variation around this average for individual roofs.

High-performance green buildings require close integration of building systems with a special focus on energy, daylighting, and material analysis during their design processes. Design process modeling and use of visualization tools can facilitate better communication and collaboration between team members; hence better integration in the design process. This paper presents a case study of the integrated design process of an Early Childhood Learning Center as performed by a team of university students and faculty. A process modeling approach of key decisions, required consultants, and virtual prototypes of the building was used during the design development stages of the case study. This case illustrates the use of process modeling and visualization tools to provide an accurate building information system for integrated teams. Through this experience, process modeling and visualization tools were found to be useful mechanisms to achieve high performance design goals and minimize design process waste.