Circadian Daylight Performance of the Electrochromic Glazing

A workflow for analysis of the EC Window non-visual daylight performance



Photo of Ahoo Malekafzali. PhD.

Ahoo Malekafzali. PhD.

Sr. Technical Solutions Consultant

Sage Glass



Electrochromic windows introduced to building market as a smart glare control solution to provide visual comfort for building occupant. EC glazing can improve human health and comfort, by changing its visual and thermal properties to block glare, heat and balance daylight. The majority of previous studies on the daylight performance of the Electrochromic windows were focused on evaluation of the visual effect of light. However, recent findings on the nonvisual effects of light on human health, confirm the necessity of assessing the circadian light performance of the EC glazing.

This study proposes a framework for evaluating the nonvisual effects of light through the development of an algorithm for measurement of circadian light in the spaces with EC windows. This algorithm is based on modeling eye-level light exposures to analyze the availability of circadian effective daylight stimulus. Since EC glazing in multi-zone configuration can dynamically change its tint pattern, this study investigates the effect of each tint state on filtering the photopic and melanopic light.

EC glazing can be used in a single or multi-zone configuration. This workflow can evaluate the impact of zoning on daylight performance for addressing human non-visual needs. The applicability of the Workflow is demonstrated using an example model: an office space with south-facing window-wall with Electrochromic glazing. The result of the analysis is presented in the format of: hourly interior map of visual and non-visual effective area.


With the recent research findings that prove the impact of light on human health and wellbeing, the importance of well daylight design in the indoor environment is more clear to

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The human eye has a dual role in detecting light for a range of behavioral and physiological responses separate and apart from sight. The discovery of non-rod, non-cone photoreceptor (ipRGCs)

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Electrochromic glazing dynamically changes its tint state to block glare, balance daylight and transmitted heat. To assess the impact of EC on circadian light a simulation workflow was developed including

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Simulation results for all the daylight hours of March 21st are reported for three test case of Single zone EC, Multi-zone EC and, clear low E glazing systems. For each

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In this study a new modeling workflow has been developed for evaluation of the circadian light performance of EC window. Properties of light that impact non-visual photoreception are Wavelength, Intensity

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Conclusion and Future Work

Electrochromic glazing in multi-zone configuration has the best visual and non-visual performance among all tested options. Even though the simulated control strategy was designed to optimize visual comfort, its impact

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Rights and Permissions

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Malekafzali Ardakan, Ahoo, “A Workflow for Assessing Circadian Daylight Performance of the Electrochromic Glazing”, 2018 Building Performance Analysis Conference and SimBuild, September 26-28, 2018, Chicago, IL, USA.