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Exploring the Effects of Solar Irradiation, Building Glazing Systems, and Tunable LEDs on the Thermal Environment for Building Energy Savings

Author
Wang, Nan
Published
[University Park, Pennsylvania] : Pennsylvania State University, 2024.
Physical Description
1 electronic document
Additional Creators
Wang, Julian X. L.
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Restricted (PSU Only).
Summary
Human thermal comfort is one of the critical variables in the indoor environment, reflecting the performance of building operations. A functional building employs both active and passive strategies to maintain human thermal comfort. The most frequently used active strategy is adopting the heating, ventilation, and air conditioning (HVAC) system, which is the most energy-consuming system in a building. Thus, using alternative sources to enhance human thermal comfort offers potential energy savings in building operations. Given this background, this dissertation aims to explore the effects of three sources -- solar irradiation, building glazing systems, and tunable LEDs -- on human thermal comfort. Due to their diverse characteristics and influencing pathways, the impacts of these factors were investigated using different methodologies and perspectives. The three endeavors can be summarized as follows: The Effect of Shortwave Solar Irradiance on Indoor Human Thermal Comfort AIM: To accurately evaluate the impact of shortwave solar irradiance (300 nm to 2,500 nm) on user thermal comfort in near-window areas and to identify the conditions necessitating precise assessments. METHODOLOGY: A spectrally-resolved method was proposed and compared with the traditional constant-value method under 41 simulated solar conditions. These conditions account for factors that affect solar spectra penetration indoors at University Park, including the time of day, day of the year, window orientations, and weather. KEY FINDINGS: The spectrally-resolved method provides significantly more accurate, albeit more complex, predictions of human thermal effects under the influence of shortwave solar irradiance. However, the more complex spectrally-resolved method is only necessary under certain conditions where larger differences between the two methods exist. A workflow was developed to provide a preliminary judgment of when the spectrally-resolved method is necessary. The Effect of Building Glazing Systems on Indoor Human Thermal Comfort AIM: To develop a thermal effect index (TEI) for glazing systems and quantify their energy-saving potentials by transmitting different levels of shortwave solar irradiance. METHODOLOGY: The thermal comfort levels associated with different glazing systems from the International Glazing Database were simulated and calculated. A TEI was generated for these glazing systems based on the calculated values. Annual energy consumption for windows with distinct TEIs was then calculated using EnergyPlus. Moreover, spectral extraction was conducted by exhaustive search and correlation evaluation to effectively predict the transmittance properties of the glazing systems. KEY FINDINGS: Window glazing systems exhibit significantly different thermal effects, resulting in drastically different thermal comfort levels under the same solar conditions. Glazing systems with varying TEIs can provide energy savings of 2.1% to 18.1% in heating load, highlighting the importance of the thermal effect of glazing systems in energy-saving potential. Additionally, a method was proposed to quickly estimate the thermal effect of glazing systems under specific solar and other conditions. The Effect of tunable LEDs on Indoor Human Thermal Comfort in the Daytime AIM: To investigate the potential of LEDs with different energy distributions to influence human thermal comfort during the daytime without disturbing visual sensation. METHODOLOGY: A randomized, crossover, within-subject trial was conducted using two LED light sources with metameric spectra (blue-rich and red-rich white LEDs) to immerse a sample of students in an office environment during the daytime. Both air temperature ascending and descending cycles were conducted to assess human tolerance, accompanied by acquisition of psychological and physiological responses. KEY FINDINGS: Under blue-rich light, subjects tend to feel psychologically and physiologically cooler and are less tolerant of cold environments. The thermal effect of light sources has the potential to reduce the use of air conditioning for heating and cooling, leading to energy savings. Solar irradiance, building glazing systems, and tunable LEDs are three sources influencing human thermal comfort, potentially serving as alternatives to energy-consuming HVAC systems. To facilitate these benefits, these three sources, along with other environmental factors, will be further explored, modeled, and integrated to achieve smart control of building environments. This smart control system would not only enhance thermal comfort for occupants but also significantly improve the overall energy efficiency of buildings. Such an integrated approach is essential for sustainable building design and operation, paving the way for greener and more comfortable living and working spaces.
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Dissertation Note
Ph.D. Pennsylvania State University 2024.
Technical Details
The full text of the dissertation is available as an Adobe Acrobat .pdf file ; Adobe Acrobat Reader required to view the file.
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