• MS of Architecture
  • James R. Jones
  • Thesis Book
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  • Recent advancements in LED lighting have challenged the assumption that natural light always helps to reduce a building's energy consumption. While LEDs are highly efficient, a study found that in a windowless office using LED lights, the energy consumption was actually less than an office with solar energy. It was observed that energy savings occur in an open office with LED lighting only when windows cover no more than 10% of the façade. Beyond this point, the increased cooling load outweighs the savings from reduced heating and lighting, making 10% the optimal window-to-wall ratio (WWR) for LED-lit offices.
  • For offices with fluorescent lighting, the energy savings continue to improve as the WWR increases to 40%-45%, due to daylight replacing electric lighting. However, beyond a 50% WWR, energy consumption rises due to the increased cooling load. The study suggests a 20% WWR as optimal for fluorescent-lit offices.
  • The different impact of daylight on LED versus fluorescent lighting is attributed to the superior energy efficiency of LEDs, which makes them less reliant on daylight to save energy. In contrast, fluorescent lights benefit more from natural lighting due to their lower efficiency.
  • However, the study emphasizes that the optimal WWR should not be determined solely by energy performance. Other design criteria such as aesthetics, structural stability, spatial quality, and human well-being should be considered. The visual connection to the outside is important for the health and experience of occupants, especially for seniors and patients. Concepts like biophilia highlight the importance of connecting with nature.
  • Therefore, the ideal WWR should be a balanced decision that considers multiple factors to satisfy all requirements reasonably.
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Zahra thesis book final.docx
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