Journal of Architectural Engineering

This paper presents a simulation environment developed to assess the energy use specific to integrated radiant heating and cooling systems. The developed simulation environment combines a transient finite difference solution for the two-dimensional model of an integrated radiant slab heating and cooling system with a resistance capacitance (RC) thermal network model for a multifloor building. The developed model of the integrated radiant system is able to account for thermal bridge effects on the energy performance of multifloor buildings. The predictions of the developed simulation environment are verified against those obtained from a detailed whole-building energy simulation tool under specific conditions. The developed simulation environment is then used to investigate the impact of thermal bridge effects on the performance of an integrated radiant heating and cooling system. Thermal bridging can affect significantly the energy performance of the integrated radiant systems by up to 8%. Several insulation configurations have been evaluated to assess the performance of the integrated radiant systems during both heating and cooling seasons for three U.S. locations: Chicago, IL; Golden, CO; and San Francisco, CA. A combination of horizontal and edge insulations is the most effective regardless of the building location. The most effective insulation configuration achieves up to 30% in heating energy savings and 35% in cooling energy savings compared with the building with no insulation.

Energy usage continues to increase across the globe, which has resulted in increased methods for conserving energy. However, most of these methods for decreasing energy consumption focus on political and economic policies, as well as curtailing usage by promoting individual energy-efficient products and practices such as appliances, electronics, and improved building envelope maintenance. To determine better methods and policies to conserve energy, individual habits and perceptions of energy usage need to be considered. One such consideration is a household’s perception of energy usage habits and the belief or self-efficacy that becoming an energy saver can make an impact. For this research, a field study was completed in the rural community of Woodbine, Iowa, to determine if self-efficacy via perceptions of energy consumption could predict actual energy usage. To examine the impact of self-efficacy on energy usage, perceptions of energy consumption were compared with actual changes in energy usage habits. During a 36-month period, the energy usage of 92 households was monitored, and the homeowners completed behavioral consumption surveys. The surveys assessed the participants’ perspectives on sustainability and energy use, comparing how perceptions relate to actual energy consumption. Homeowners who changed their energy usage habits were determined to be in the bottom half of energy users in their community; however, homeowners’ beliefs that their habits affect energy usage were more accurate predictors of their actual energy consumption. The results suggest a stronger correlation and effect size between self-efficacy and energy usage compared with changes in consumption habits and energy usage. This information can be used to better conduct interventions aimed at reducing community energy consumption. Future research should target psychological beliefs on energy consumption in addition to actual behaviors.

There is no general consensus among researchers for selecting appropriate set of ground motions for the evaluation of inelastic seismic response of plan-asymmetric structures. In this backdrop, the role of important ground motion characteristics on the demand of a plan-asymmetric system is studied by using a number of records with widely varying characteristics but adjusted (using wavelets) to a common spectral shape. An equivalent single-story rigid-diaphragm model with simple elastoplastic hysteresis behavior is employed. Efficient strength design, viz, center of strength–center of mass (CV-CM)–coinciding strategy, is adopted in recognition of the strength-dependent stiffness characteristics of the load-resisting elements. It has been shown that the torsion-induced response of such systems is statistically insensitive to important ground motion parameters such as duration, frequency content, the interrelationship between two horizontal components, and the energetic length scale. Conversely, this study shows that a remarkable correlation exists between the carefully selected ground motion parameters and overall seismic demand as a result of coupled lateral-torsional vibration. The results motivated the authors to conceptualize a master curve that offers an a priori estimate of inelastic seismic demand of asymmetric systems when two widely used ground motion parameters, viz, peak ground acceleration (PGA) and mean period ($T_m$), are known. Thus, this study provides a background for dispelling the long-held controversy regarding the selection of an appropriate ground motion suite for assessing torsional response.

The improvement of the building stocks represents an enormous potential for the reduction of energy use and greenhouse gas emissions. Therefore, it is crucial to convince and support building owners to invest in sustainable renovation. The main objective of this paper is to develop a more structured and holistic method of decision making toward nearly zero-energy building renovation. The methodology is evolutive, implementable on a large scale, and allows an optimal integration of nonexpert decision makers. In practice, such a scheme allowed most behavioral barriers to sustainable home renovation to be overcome. The homeowners were better integrated and their preferences and immaterial values were better taken into account. To keep the decision-making process economically viable and timely, the process as known today still needs to be improved, and new tools need to be developed. This paper presents a new scheme: the integrated renovation process. One successful case study is introduced, and recommendations for future developments needed in the field are provided.

Nonstructural vertical partitions and cladding can have a significant effect on the vibration serviceability of floor systems. A typical modern office building, consisting of steel–concrete composite floor systems, was created to investigate the potential beneficial effects of integrating nonstructural partitions into structural floor systems to reduce floor vibrations due to walking excitation. Two models of this building are presented: one to represent the completed building with an open-plan layout and another with partitions added in a beneficial pattern to enhance the floor’s vibration performance. The addition of nonstructural partitions successfully reduced floor accelerations due to walking excitation and helped the floor to satisfy the vibration serviceability criterion for office floors. The potential of vertical full-height nonstructural partitions and cladding to transmit vibrations between floors was also investigated. A vibration transmission simulation was conducted on the finite-element (FE) model to quantify vibration transmission between floors through the structural frame and nonstructural vertical partitions and cladding. The results were then compared with experimental results previously recorded on the floors of a real-life Charles Institute Building in Dublin, Ireland, featuring the same type of partitions but with a different structural frame. It was concluded that both the FE model and the real-life building featuring structural elements and full-height partitions have the potential to transmit a significant level of vibrations between two adjacent floors. The results presented in this paper will be of interest to design engineers and researchers in the area of vibration serviceability of floor systems because it highlights the potential of nonstructural elements to reduce the floor vibration response to acceptable levels, as well as their ability to transmit vibrations between floors.

The impact of buildings on the environment has created the need for green or sustainable buildings, which aim to reduce energy and resource consumption. Sustainable building assessment methods have emerged in recent years as a means to evaluate the performance of buildings across a broad range of sustainability considerations. This research presents a conceptual model for the assessment of sustainable commercial buildings with the use of fuzzy logic and the analytic hierarchy process (AHP). It covers 100 sustainability criteria. The proposed building evaluation model depends on two types of parameters: endogenous (constants: global weights of criteria) and exogenous (variables: performance score of building for each criterion). A building’s sustainability score reflects the interplay between these two parameters. Global weights of criteria can be developed through AHP. The performance scores of criteria can be determined through fuzzy logic. The proposed approach of building evaluation can produce significant benefits that are not likely to result from conventional practices.

A hybrid modeling framework was constructed to investigate the uncertainty in modeling the energy consumption of an existing campus building with minimal instrumentation. The hybrid framework consisted of a dynamic model of the building’s conditioned spaces, coupled with an empirical model of the building’s HVAC system. The empirical model was calibrated using linear regression of available HVAC system temperature and flow measurements from a building automation system to develop estimates of internal loads and relationships between envelope heat gains/losses and indoor/outdoor temperatures. Crabtree Hall, a 40-year-old building at the University of Pittsburgh, was used as an illustrative case study for this approach. A separate data collection time frame was used for empirical model verification in addition to the initial model development time frame. Comparative results from the model showed a 20% normalized RMS deviation for hourly net heating and cooling for the average day in a given month. This close agreement highlights the possibilities of this approach for rapid assessment of energy consumption and retrofit potential in existing buildings. Future work will include additional refinement of the components of energy consumption using mobile equipment to collect targeted measurements at additional locations, as well as cross-checking existing measurement locations. Additional future work should include extending this method to buildings with more complex HVAC systems, such as variable-air-volume systems and multiple thermal zones, to further verify and improve its robustness.

A complete sustainable-performance analysis that takes into consideration the whole of the triple bottom line of sustainability is necessary when one needs to balance social, economic, and environmental impacts in an optimal cost-effective design based fundamentally on sustainability performance objectives. This study introduces a methodology that can translate seismic building damage into clearly quantifiable social, economic, and environmental impacts, which can be used when selecting repair methods appropriate for various states of building damage and for the local economic and environmental situation. The authors also propose a lifecycle-assessment framework with which one can evaluate the costs and benefits associated with a seismic design over the lifecycle of a building. Two case studies are presented. The first case assesses the sustainability performance of a single RC building under seismic risk. The second case, taking into account the uncertainty associated with seismic events, comprises a risk-based cost-benefit analysis of the desirability, in terms of the three sustainability metrics (separately and in combination), of two seismic retrofit designs on a regional scale. A comparison of the relative merits of the two proposed retrofit designs revealed that preventing buildings from becoming irreparably damaged plays an important role in increasing the cost-efficiency of a retrofit design. These findings also indicate that, although neither design can be considered feasible with respect to the three sustainability metrics individually, the lower-cost/lower-resistance design is justifiable if measured by the combined benefit from all three metrics, expressed in monetary terms. This finding emphasizes the necessity of a complete sustainable-performance analysis for achieving a cost-effective design. Finally, when comparing all three metrics in monetary terms, the savings associated with the reduction in fatalities contribute the most to the total expected benefit of a retrofit project, followed by reduced repair costs and reduced CO₂ emissions.

It is important for students in academic disciplines related to building design and construction to gain an understanding of the different sustainable design considerations that will affect a building’s performance. Additionally, it is important for these students to be able to generate, visualize, and assess the performance of alternative design options to determine the best possible approach. The research presented in this paper tasked students with performing a building redesign activity in which they had to design, visualize, and assess exterior wall designs to retrofit an existing facility and improve its sustainable performance. It was of interest to understand how augmented reality and simulation game technologies would influence students’ design processes during the activity. To measure student performance, 34 architectural engineering students, 47 architecture students, and 27 civil engineering students were given the same design activity using an augmented reality–based educational game called ecoCampus. The results of their work were compared with those of 65 students who completed a similar design activity using only blank sheets of paper and of another group of 23 students who used a paper-based approximation of the computerized ecoCampus. The findings indicate that students in all disciplines who used ecoCampus were able to break the tendency toward design fixation. These students were also able to use the application to assess their designs and generate additional concepts with better overall performance across all disciplines compared with the students who used paper-based formats. Although these observed behaviors were beneficial, the students who used ecoCampus also demonstrated a tendency to experiment with the application and occasionally create unrealistic, novelty designs to try to break the game. The findings from this work will help inform future efforts to leverage augmented reality and simulation game technologies for other use cases to allow users to assess what-if design scenarios in which they might otherwise be prone to design fixation.

Sliding of contents during past earthquakes has caused injury, disruptions, and damage. As such, equations to predict the maximum sliding displacement of the contents are required to include its effect in building performance assessments. This paper examines six different prediction equations, including a new equation derived in this paper based on the first sliding excursion of contents subjected to sinusoidal floor motion. The accuracy of these equations was assessed by comparing the ratio of the maximum sliding displacement obtained from an analytical study to that from the prediction. The analytical study consisted of modeling the sliding movement of contents in three elastically responding 5-story buildings of varying periods subjected to the entire set of 3,225 unscaled ground motion records available on the Pacific Earthquake Engineering Research Center’s database. It was found that the prediction equation derived in this study had the best fit of all prediction equations considered, with the median sum of squared relative error between 4 and 6 times smaller than the next best prediction.

Phase-change materials (PCMs) have a high heat of fusion compared to that of traditional material, and for this reason, they are able to store and release larger amounts of energy at their transition temperature. The inclusion of PCMs in buildings has attracted much interest worldwide because of their ability to reduce building energy demand and increase indoor comfort. This paper presents the development and testing results of a concrete tile system with microencapsulated PCMs. The concrete tiles were cast for use in a high-performance house built for the Solar Decathlon China 2013 competition. The paper shows that the addition of PCMs reduced the overall compressive and flexural strength properties of the concrete. A more than 25% decrease in compressive strength was observed with the addition of 20% PCM per volume of concrete. However, a significant improvement in the thermal properties of the concrete tile PCMs was measured. The thermal energy storage capability of the PCM-enhanced concrete tiles was determined using the dynamic heat flowmeter apparatus method. It was demonstrated that a 3.8-cm-thick concrete tile with 13.5% PCM had a thermal storage capacity equivalent to a 5.9-cm-thick tile of regular concrete, a 155% increase in thermal storage capability. Finally, the results indicate that the use of PCM in concrete floor tiles can significantly improve their thermal behavior, especially in lightweight buildings, while also keeping the concrete’s strength loss within an acceptable range.