User satisfaction and energy use behavior in offices in Qatar

The occupant behavior significantly contributes to the total energy use in buildings and its understanding is greatly needed in energy analysis/simulation studies. Uncertainties about the occupant behavior adversely affect the building performance predictability of the simulation models. As field data in Qatar on occupant energy use and behavior was unavailable, we conducted an environmental satisfaction and energy use survey in the city of Doha, Qatar in seven office buildings. Building occupants were highly satisfied with their work environments with respect to most of the environmental parameters excepting acoustics. Access to operable controls such as windows, thermostats improved their satisfaction. Subjects in private offices were more satisfied with their work environments. We noted the self-declared productivity of respondents to be high in general. It was significantly higher in offices with better occupant access to temperature controls. Noise level dissatisfaction was the highest in high partitioned cubicle offices and satisfaction was high in open plan offices. These findings provide vital design direction for new offices and environmental systems design and for managerial motivational campaigns. Practical application: Using field study data, we analyzed the occupant behavior and environmental satisfaction in offices in Doha, Qatar. The Middle East in general and Qatar in particular are known to consume enormous energy for buildings leaving a large ecological footprint. The finding of this study informs the designers of air-conditioning systems about the user behavioral patterns. Further, these findings help the building managers in designing targeted energy awareness/saving campaigns, as user motivation is vital in energy saving. ? 2018, The Chartered Institution of Building Services Engineers 2018.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Qatar Foundation funded this research through grant number NPRP 7-143-2-070

Building energy model calibration using automated optimization-based algorithm

Multiple numbers of Building Energy Simulation (BES) programs have been improved and implemented during the last decades. BES models play a crucial role in understanding building energy demands and accelerating the malfunction diagnosis. However, due to the very high number of interacting parameters, most of the developed energy simulation programs do not accurately predict building energy performance under a known condition. Even the energy models which are developed with the very precise assignment of parameters, there is always significant discrepancies between the simulation results and the real-time data measurements. Current study develops an optimization-based framework to calibrate the whole building energy model. The optimization algorithm attempts to set the identified parameters to minimize the error between the simulation results and the real-time measurements. Due to the high number of parameters, the developed optimization algorithm utilizes a Harmony Search algorithm as its search engine coupled with the energy simulation model to accelerate the calibration process. Moreover, to illustrate the efficiency of using the developed framework, a case study of the office building is modeled and calibrated and the statistical analysis was conducted to assess the accuracy of the results. The results of the calibration process show the reliability of the framework. - 2019This work was supported by the Qatar National Research Foundation (QNRF)/National Priorities Research Program (NPRP 7 - 143 - 2 - 070). Authors would like to acknowledge their supports through this research.Scopu

The Application of Water Coupled Nonlinear Ultrasonics to Quantify the Dislocation Density in Aluminum 1100

This article investigates water coupled nonlinear ultrasonic testing to characterize dislocation density in Aluminum 1100 specimens. The different levels of dislocation densities are introduced to the samples by applying different levels of plastic strain at tensile loading. The ultrasonic testing includes 2.25 MHz transducer as transmitter and 5.0 MHz transducer as receiver in an immersion tank. In order to reduce the error introduced by Fourier Transform to obtain the amplitudes of the first and second harmonics, Wavelet Transform is applied to the transient data, and the wave amplitudes are identified after the wave is decomposed into its harmonics. The results of Fourier Transform and Wavelet Transform are compared, and concluded that Wavelet Transform provides more reliable reading in wave harmonic amplitudes. While water has significant nonlinearity within itself, the immersion ultrasound results agree with the literature of oil coupled ultrasound as well as the scanning electron microscopy (SEM) and Rockwell C hardness results of the specimens that the nonlinearity coefficient increases with the increase of dislocation density in aluminum.</p