Harmonizing Visual And Non-Visual Light Effects For Energy Efficient Classrooms' Designs
Open Access
- Author:
- Alkhatatbeh, Baraa
- Graduate Program:
- Architectural Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 05, 2023
- Committee Members:
- James Freihaut, Program Head/Chair
Somayeh Asadi, Chair & Dissertation Advisor
Rahman Azari, Outside Unit & Field Member
Julian Wang, Major Field Member
Houtan Jebelli, Major Field Member - Keywords:
- Classrooms' design
visual and non-visual effects of light
daylighting
Multi-objective optimization
energy use - Abstract:
- The effects of light on the human body can be generally classified into visual effects (IF) and non-visual effects (NIF). The IF is responsible for vision, while the NIF is responsible for many physiological, psychological, and behavioral rhythms. Daylight has been usually preferred over artificial light to meet the IF and NIF needs. The variable amount, spectral composition, timing, and duration of daylight throughout the day make it more potent in regulating circadian rhythms. Researchers reported that children and adolescents are more sensitive to lighting (both daylight and artificial light) than adults. This calls for special consideration for classrooms design as children spend around 30% of their life in school. Decisions made at the early stages of classroom design significantly impact the visual and non-visual benefits obtained from light, as the built environment can alter the light characteristics inside spaces. These decisions also influence the energy performance of classrooms and schools. This study uses multi-objective optimization to find the optimal classroom design in different climate zones in the U.S. based on visual, non-visual, and energy performance criteria. The visual benefits of daylight are expressed as the daylighting conditions at the horizontal desk-plane, while the non-visual benefits are expressed as the daylighting conditions at the vertical eye-level. Two classrooms-corridors typologies are explored in this dissertation: classrooms connected to single-loaded corridors and classrooms connected to double-loaded corridors. The optimal classrooms design and the design parameters’ level of importance have been identified for both typologies. The Department of Energy (DOE) primary school reference building has been used as a reference model as it represents 70% of U.S. schools. Results have shown that there are similar optimal solutions in terms of each objective across closely located climate zones for the single-loaded corridor typology. The daylighting and energy performance of these classrooms is mainly influenced by the window orientation and window to wall ratio (WWR). The classroom design with the best overall performance in all objectives has a rectangular plan and a northeast-oriented window. All optimal solutions have 3-5% higher window-to-wall ratio (WWR), higher window head height, and 25-35% less energy use than the reference classroom. Finding the optimal design of classrooms connected to double-loaded corridors is more complex. The oppositely oriented classrooms have competing objectives to improve their daylighting performance. The results indicate that the 3:2 width-to-depth plan shape in most optimal solutions performs better than the 5:4 width-to-depth plan of the reference model. Accordingly, wider windows and higher head height in the optimal design were able to allow more daylighting to the depth of the oppositely oriented classrooms while reducing the energy use. The results show that optimal classrooms’ design connected to double-loaded corridors, including window dimensions, orientation, and WWR vary by the climate zone. Although WWR is the most important design parameter on horizontal desk-plane and vertical eye-level for most cases, other parameters can be at least equally important especially for the vertical eye-level daylighting across different climate zones. The results of this dissertation can give guidance to architects, designers, and decision makers on classrooms design across studied climate zones.