An understanding of indoor environmental quality (IEQ) and its effects on occupant well-being can inform building system design and operation. The use of wearables in field studies to collect subjective and objective health performance indicators (HPIs) from a large number of occupants could deliver important improvements in IEQ. To facilitate the use of wearables in IEQ studies, there is a need to identify which HPIs should be collected and to evaluate data accessibility from these devices. To address this issue, a literature review of previous IEQ studies was conducted to identify relationships between different IEQ factors and HPIs, with a focus on HPIs that were collected using wearables. A preliminary assessment of data accessibility from a selected wearable device (Fitbit Versa 2) was performed and documented. The review suggested the need to further investigate and collect sleep quality parameters, heart rate, stress response, as well as subjective ratings of comfort using wearables. The data accessibility assessment revealed issues related to missing data points and data resolution from the examined device. A set of recommendations is outlined to inform future studies.

Researchers have been exploring the influence of light on health in office settings for over two decades; however, a greater understanding of physiological responses and technology advancements are shifting the way researchers study the influence of light in realistic environments. New technologies paired with Ecological Momentary Assessments (EMAs) administered via smartphones provide ways to collect information about individual light exposure and occupant response throughout the day. The study aims to document occupant response to tunable lighting in a real office environment, including potential beneficial or adverse health and well-being effects. Twenty-three office employees agreed to participate in a twelve-week study examining occupant response to two lighting conditions (static vs. dynamic). No significant differences were observed for any of the measures, highlighting the importance and complexity of in-situ studies conducted in realistic environments. While prior office studies have shown a significant influence on daytime sleepiness and sleep quality, research has not shown mood or stress to be significantly impacted by lighting conditions. Correlation analyses regarding lighting satisfaction, environmental satisfaction, and visual comfort demonstrate a significant relationship between certain items that may inform future studies. Further, the high correlation means it is reasonable to assume that many environmental factors in offices can influence occupant behavior and well-being.

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Solid-state light sources can be more prone to larger temporal light modulation (TLM) than conventional sources. TLM visibility depends on wave shape, frequency, modulation depth and duty cycle, and is affected by the sensitivity of the observer. TLM can be visible well above the critical flicker fusion frequency, when there is relative movement between the observer’s eyes and light source, lighted space or moving objects in the field of view. This human subjects experiment explored visibility of the stroboscopic effect (SE) versus the phantom array effect (PAE) with targeted tasks under 74 TLM waveforms. The results showed the SE visibility peaks between 90 Hz and 120 Hz, while the PAE visibility peaks between 500 Hz and 1000 Hz. The phantom array is visible to sensitive participants at 6000 Hz. Both effects are more visible under rectangular versus sinusoidal TLM, higher modulation, and when duty cycles are 10% or 30% versus 50%. Higher sensitivity participants, differentiated using the Leiden Visual Sensitivity Scale, rated TLM waveforms as more visible, especially those inherently harder to see. This work lays a foundation for a PAE metric and guides driver and dimmer designers toward electronic circuits that minimize the visibility of TLM in LED products.

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