Journal of Architectural Engineering

This paper presents a case study of an institutional building's heating, ventilation, and air-conditioning (HVAC) system that was not providing satisfactory comfort control. In the investigation, significant design, construction, and operational problems were discovered. Poor communication between the architect, consulting engineers, construction personnel, and owner/financier was a significant factor in the failure of the comfort control system. Problems with the windows, insulation, design of the system zones, supply air fan, and indoor air quality due to poor ventilation were also identified and investigated. Recommendations for correction of these problems range from obvious, low-cost actions to more substantial retrofits of the HVAC system. Actions that should have been taken during the design stages of the project, as well as postoccupancy corrective measures, are discussed with emphasis on comfort, health, and economics. The results of this project show that a well-designed HVAC system will operate poorly if the building is not constructed or operated as planned. This case study should help institutional building contractors, owners, and operators avoid or identify and correct similar problems with their planned and existing comfort control systems. To ensure successful operation of their designs, HVAC designers need feedback from the architect, contractors, building owners, and occupants.

Severe windstorm events such as Hurricane Andrew in 1992 have underscored the vulnerability of building envelopes to breaching under the combined effects of windborne debris impacts and wind pressures. Damage to building interiors and disruption of building functions are exacerbated greatly when building envelopes are breached. When the inner glass ply in a laminated glass window unit is unbroken, the integrity of that part of the building envelope is preserved—provided that the inner glass ply has sufficient resistance to subsequent positive and negative wind pressures. In an effort to develop glazing systems that are resistant to breaching due to windborne debris impacts, laboratory studies have been conducted to investigate the resistance of various laminated glass units to inner glass ply fracture when subjected to simulated windborne debris impacts. Laboratory data indicate that increased interlayer thickness (i.e., the thickness of the polymeric layer between the glass plies in a laminated glass unit) reduces significantly the observed probability of inner glass ply fracture resulting from small windborne debris impacts.

This investigation is a computation of the trajectories of raindrops of various sizes in an irrotational, two-dimensional (2D) wind that flows to the side of a building sized horizontal cylinder. Vertical surface winds, as derived from a published survey of pressures on a model of a high-rise building, are used to modify the “cylinder wind” trajectories near the balconies to determine their ability to shelter ceiling-height, unsealed windows against impact and intrusion of rain there. It is determined that in a severe open country storm wind, portions of all drops with sizes smaller than about 2.3 mm in diameter will be driven upward to impact on unsealed window tops on the three floors above the stagnation point. Other drops sized from 4.5 mm down to the very smallest (0.1 mm) will fall below the stagnation point on the building. All window tops on the lower 10 floors will be well sheltered. Some favorable estimates of the accuracy of the calculations and some physical observations of vortex wind on the balconies of the building are provided. A scale effect was determined for a higher building and for one particular drop size.

The options of increased ventilation and/or increased filtration to improve indoor air quality in existing buildings were compared. Three buildings, located in Greensboro, N.C., were studied in order to predict the construction, retrofit, and operating costs associated with each option. The analyses included reviews of the building design drawings; site visits and inspections of the heating, ventilating, and air-conditioning systems; review of construction costs; and review of annual utility bills. Retrofit costs were estimated based on supplier quotations for equipment and construction labor estimating guides. Increases in annual maintenance costs were based on the replacement costs of filters plus 5 of the cost of all additional equipment installed. Changes in energy costs were projected using the ASEAM computer simulation program. For each building, the outdoor air was increased from its current operating amount to 100 outdoor air. Similarly, particulate and gas-phase filtration was incrementally increased to filter efficiencies of 95. The retrofit and operating costs and the estimated reduction in indoor air contamination levels were projected. A final costs comparison of alternatives was computed based on a system performance that would reduce indoor air contamination by 80. As expected, meeting the performance target was most costly for the building with split system heat pumps. The building with rooftop units, economizer cycle capability, and a central exhaust system was less expensive. The building with the chilled water system and air handling units with economizer cycles was least expensive. This last building, however, had the highest initial construction cost.

During the last two decades, various exterior wall systems have been applied to buildings in Saudi Arabia. The evaluation and selection of most of the exterior wall systems were based on the designer's experience, with no systematic approach used for the evaluation and selection. This paper presents an evaluation and selection technique based on value engineering principles for exterior wall systems. The study includes 14 exterior wall systems. The weighted evaluation techniques were used to evaluate the wall systems. The most important criteria used in this evaluation were obtained from a survey of 25 professional designers and consultants. These criteria include structural stability, strength, durability, fire safety, initial cost, maintainability, availability, aesthetics, and maintenance cost. The evaluation technique has helped in the selection and prioritization of a few wall systems among the various systems. This technique is recommended for the evaluation and selection of similar construction systems.