The quality and controllability of the building façade can significantly contribute to building indoor environmental quality (IEQ) as well as the building's energy efficiency. Advanced technologies that support a façade's dynamic response to climatic changes, such as electrochromic (dynamic) glazing, have emerged as smart systems for IEQ and environmental sustainability. This research summarizes a four-season study of office workers moving from a floor with conventional blinds to work environments equipped with smart dynamic glazing which changes tint in response to weather condition to control daylighting levels. Multiple occupant environmental satisfaction surveys were conducted over one year to investigate differences in environmental and psychological responses to office settings with manual, and often static, facades as compared to offices with dynamic glazing. This research confirms that dynamic glazing significantly affected occupants' environmental satisfaction-enhancing individuals' environmental perceptions and psychological health-as compared to manual blinds. It reveals that the occupants in work environments with dynamic glazing reported 21.7% higher productivity gains, 24.8% increased ability to relax, 12.7% improved concentration, 25.3% better moods and 29.4% greater alertness than when they were in offices in the same building with manual shading devices. Also, the dynamic feature of the smart glazing showed a significant contribution to perceived work productivity while enhancing positive emotional responses by an average of 26%.Energies 2020, 13, 60 2 of 20 sustainability. Most significantly, dynamic glazing is known to contribute to reduced glare, thermal discomfort and reduced cooling loads. The visual transmittance of dynamic glazing can be increased or decreased based on pre-defined control algorithms, and it can control the illuminance of natural light admitted through glazing in an optimal way to enhance the visual quality and allow for continuous window views without compromising the thermal-quality condition. These technical merits have been especially important for office and healthcare facilities where the occupants' environmental health and work productivity are important.Recent research has investigated the efficacy of dynamic glass, focusing predominantly on energy performance. Tavares et al. investigated the energy conservation potential of adopting electrochromic windows in a Mediterranean climate [15]. The research confirmed that electrochromic glazing saved 15-20% energy in a cooling dominant climate depending on orientation, and the impact was most significant for the west façade. DeForest et al. simulated energy consumption of three building types in 16 U.S. climate zones, identifying that electrochromic windows outperformed other glazing choices in x of the 48 set of locations and building types [16]. Picco et al. used both experimental tests and computation simulations to evaluate the impact of electrochromic glazing on energy efficiency [17].This study tested four different...
Occupant surveys were conducted in 4 office buildings, 2 with traditional non-tinted low-e glass (LeG) and 2 with electrochromic glass (EC). 106 employees working in these buildings volunteered to participate in the study. Results showed that subjective reports of overall ambient lighting conditions were comparable in the buildings. However, EC optimizes daylight and reduces sunlight glare, and significantly more workers sat close to the windows in the EC buildings compared to the LeG buildings. Workers in the EC office buildings reported significantly better daylight, significantly less adverse glare, and significantly fewer symptoms of computer vision syndrome than those in the LeG buildings.
Fatigue experiments were performed on human subjects to study muscle fatigue measurements of the erector spinae muscles during cyclic and prolonged static stooped bending using electromyography (EMG). Nineteen subjects participated in the study. The median muscle firing frequency (fm) data of the erector spinae muscles were measured noninvasively and continuously during simulated cyclic and prolonged stooped work. In the prolonged condition, the subject conducted an isometric stooped work at 4:1 work to rest ratio; whereas in the cyclic condition, the subject conducted an isometric stooped work at 4:1 work-to-rest ratio; each followed by a recovery period. To quantify the rate of fatigue, a fatigue index was defined as the change in the fm with respect to muscle activation time. All measurements were normalized to each subject's individual erector spinae maximum voluntary contraction using the BieringSørenson Muscle Endurance test for lower back endurance as control measurement. The results indicated that the use of EMG showed no significant differences in the muscle fatigue between cyclic and prolonged stooped conditions. However, when EMG results for both are compared to the control conditions, similar fatigue responses are shown. This may be an indication that both cyclic and prolonged stooped work conditions are equally detrimental to the spine, which calls for effective interventions to limit their effects on workers who commonly perform these types of tasks.
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