Journal of Architectural Engineering

Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.

Data were studied from tests of new and weathered rectangular annealed glass samples, each consisting of numerous specimens, loaded to fracture. The maximum principal tensile stress at the fracture origin was compared with the single largest maximum principal tensile stress (SLMPTS) within each specimen. The findings indicated that maximum principal tensile stresses at the fracture origins were always less, often significantly so, than SLMPTS in the specimens. In addition, fracture origins rarely, if ever, coincided with the location of SLMPTS in a rectangular glass lite specimen. These results support the notion that glass thickness selection should not be based on a maximum principal stress method.

The use of energy service performance contracts (ESPCs) has become a popular method for financing energy conservation upgrades. To date, the use of the stipulated savings approach, often expressed as tables and equations, has been a popular method for calculating energy savings in ESPCs. However, no studies to date have confirmed or denied the literature findings regarding the use and acceptance of this method in the current industry through a systematic investigation. Therefore, this research identified other practices by conducting an ethnographic study with subject-matter experts, by reviewing publicly available technical reference manuals, and by analyzing a typical utility assessment report from a recent ESPC. In particular, the methods for quantifying lighting and lighting control measures were explored in detail. The findings indicate that the current industry relies on a stipulated savings method as a foundation for determining the baseline and postretrofit savings. In addition, the current industry relies on experienced engineers and their valuable tactical and institutional knowledge to build upon the stipulated equations and tailor them to individual projects.

Different techniques and guidelines are available to select and quantify the savings from energy service projects. In this article, a comparison is presented between the engineering algorithms supported by energy service performance contract technical reference manuals and an as-built, calibrated whole-building energy simulation model. A lighting energy retrofit measure was selected to demonstrate the methodologies. The results show that the industry methods of quantifying the total savings for the lighting energy retrofit measure underreported the savings as compared with the as-built, calibrated whole-building energy simulation model. In particular, the breakdown of savings (e.g., electricity savings, adjustments to energy savings, and demand savings) was inconsistent between the various industry methods that are currently in use. The differences identified in this study were location specific and weather driven, and also included agreements with the local utility companies to quantify the demand savings. The study results also indicate that substituting a single measured occupancy parameter did not improve the current industry methods.

Ideally, minimum outdoor air and building static pressures are controlled through feedback controllers with the use of airflow and pressure sensors in air-handling units (AHUs). Unfortunately, because these sensors are not always installed in AHUs, it is common to maintain the minimum outdoor airflow by fixing the AHU control dampers at minimum positions and maintain the building static pressure by tracking the return fan speed with the supply fan speed. The purpose of this paper is to evaluate the system performance of these alternative controls. The outdoor airflow and building static pressure of an AHU is simulated using a nonlinear network solution. The simulation results show that the fixed damper position method can approximately maintain a constant outdoor airflow ratio with an appropriate damper connection if the building static pressure is perfectly controlled. The return fan speed linear tracking method along with the fixed damper position method shows performance in maintaining the minimum outdoor airflow ratio and positive building static pressure that is better than that with the return fan speed proportional or offset tracking method.

Housing units in the United States account for 18% of the total greenhouse gas emissions and 58% of public-supply water consumption. These negative environmental impacts of housing units can be reduced by integrating green building measures and fixtures, such as geothermal heat pumps and water-saving plumbing fixtures. The integration of these green measures often leads to an increase in the initial costs of the housing units, and therefore decision makers need to study and optimize the potential trade-offs between the environmental performance of housing units and their initial costs. This paper presents a multiobjective optimization model that is capable of optimizing housing design and construction decisions to generate optimal trade-offs between maximizing the environmental performance of housing units and minimizing their initial costs. The model was designed to maximize housing environmental performance during its operational phase by reducing its greenhouse gas emissions and water consumption. The model was developed in two main phases that formulated and implemented the model with the use of multiobjective genetic algorithms to provide the capability of generating Pareto optimal trade-offs between housing cost and environmental performance. Analysis of an application example is presented to demonstrate the use of the model and its capabilities in identifying Pareto optimal configurations of housing design and construction decisions. The primary contributions of this research to the body of knowledge include its comprehensive set of metrics and novel methodology that can be used to measure and quantify the impact of the design and construction decisions of housing units on their environmental performance, including greenhouse gas emissions and water consumption, and its novel multiobjective optimization methodology that is capable of generating Pareto optimal trade-offs between the environmental performance of housing units and their initial costs.

The green building concept has recently gained momentum, and the success of green projects to a large extent depends on the lifecycle cost. Water conservation components contribute almost 12%–15% to the capital cost of a conventional residential building. This paper aims to analyze the financial feasibility of using water conservation components by evaluating their lifecycle costs and operational savings in large mass housing projects. Four components have been evaluated for a case project located in a metropolitan suburban location in India. To analyze the benefits, two different water tariffs are considered: local corporation combined with mineralized water and well water. Lifecycle cost analysis (LCCA) suggests that, excluding the rainwater harvesting component, the significant share of cost for all other components is related to maintenance, repair, and replacement activities. Results of the analysis suggest that water components do not pay a return when a local corporation water tariff is considered at an 8% discount rate. The results of this study are expected to benefit project stakeholders in mass housing projects for their financial and budgetary decisions, thus making implementation of these component-based designs feasible.

Cross laminated timber (CLT) is a new panelized mass timber product that is suitable for building tall wood buildings (higher than eight stories) because of its structural robustness and superior fire resistance as compared with traditional light-framed wood systems. A number of tall CLT buildings have been constructed around the world in the past decade, and taller projects are being planned. The energy efficiency of this emerging building type was evaluated numerically in this comparative study with the use of a building energy simulation program. A 10-story multiunit residential building model constructed using CLT was simulated and compared with a light-frame metal construction model with the same floor plan. A sensitivity analysis was also conducted to study the impact of different weather profiles, building types, and internal load conditions on building energy consumption performance. It was concluded that CLT generally provides significant improvement on heating energy efficiency as a heavy and air-tight envelope, but its energy performance efficiency can be affected by weather, building size, internal loading, and HVAC control.

The roof-to-wall connection in a house is designed to transfer the uplift and lateral loads during strong winds by providing a continuous load path from the roof to the foundation. The uplift capacity and failure mode of the connection depends on the number and type of fasteners (nails), timber species, type of framing anchor, and constructions defects. This paper presents experimental results that were used to assess the uplift capacity variation of typical roof-to-wall connections. Based on tests with two types of connections (triple grip and truss grip) assembled with two types of timber (radiata pine and spruce pine), nails (hand and gun), and framing anchors (triple grip and universal triple grip), the results show that the variation in timber species, nail, and triple grip type changes the strength and the failure modes of the connection. The strength of the connection was reduced by about 24% when the timber species was changed from radiata pine to spruce pine and the hand nail to gun nail on the triple grip connection. This study also showed that construction defects in roof-to-wall connections influence the design uplift capacity. If there are two missing nails in the hand-nailed triple grip connection (i.e., one nail on the truss and another one on the top plate) the design uplift capacity reduces by about 40% of the ideal hand-nailed triple grip connection. This study identified the critical nails and their locations required to mitigate failure of the roof-to-wall triple grip connection subject to wind loading.

This study presentes a new nonparametric structural damage detection algorithm that integrates self-organizing maps with a pattern-recognition neural network to quantify and locate structural damage. In this algorithm, self-organizing maps are used to extract a number of damage indices from the ambient vibration response of the monitored structure. The presented study is unique because it demonstrates the development of a nonparametric vibration-based damage detection algorithm that utilizes self-organizing maps to extract meaningful damage indices from ambient vibration signals in the time domain. The ability of the algorithm to identify damage was demonstrated analytically using a finite-element model of a hot-rolled steel grid structure. The algorithm successfully located the structural damage under several damage cases, including damage resulting from local stiffness loss in members and damage resulting from changes in boundary conditions. A sensitivity study was also conducted to evaluate the effects of noise on the computed damage indices. The algorithm was proved to be successful even when the signals are noise-contaminated.

This paper presents the results of research that was conducted by interviewing architects and structural engineering practitioners to find more specificity on the topic of integration among the two fields. The responses analyzed here are those that portray the undesirable integration missteps. The results yield a framing of integration that is narrower than one might expect. Two areas of poor integration identified by architects give particular insight into the structural engineering and architecture relationship: the improper intellectual framing of the project and the perceived conservatism of the engineer. For engineers, the responses centered on the failure of the regular interactions of the professionals and the lack of architectural leadership. Beyond the profession-specific themes, a comparison of the responses from all practitioners shows that integration lapses happen when the structure itself is too large or a lack of foresight causes errors to arise during construction. The opportunity to review and criticize examples of bad integration, especially when contrasted with positive definitions, demonstrates that integration is multifaceted. Small process-based missteps can color the way a practitioner views the success of integration in a project or work methodology. In comparison to positive examples of integration, which include hope, aspiration, and aims, negative factors show that, along with the ideals, the daily working relationship between the architect and engineer is equally important.