Thermal Comfort Assessment of Multi-Zone Electrochromic Window

A New Approach for Evaluating Human Thermal Comfort in an Office with EC Window



Photo of Ahoo Malekafzali, Ph.D.

Ahoo Malekafzali, Ph.D.

Sr. Technical Solution Consultant

Sage Glass



Access to natural daylight and connection to the outdoor environment is one of the key elements of contemporary architecture. This design concept is characterized in buildings by large area glazing. However, large openings without proper shading strategy can cause visual and thermal discomfort for occupants in building perimeter zones. Electrochromic glazing can dynamically tint and vary its visual and thermal properties. EC glazing can prevent large amounts of solar energy from passing into the building interior to prevent over-heating.

This paper focuses on analyzing how Electrochromic (EC) glazing can affect occupant thermal comfort. Advanced human thermal comfort model developed by UC Berkeley and Center for Built Environment (CBE) was used in this study to predict body comfort and sensation. The level of accuracy of advanced thermal comfort model which can predict comfort for local body parts makes it a unique tool for assessment of comfort under non-uniform environments which is common due to variation in solar angle and solar radiation intensity.

For assessing thermal comfort performance of the Electrochromic glazing, two identical offices spaces, one with Electrochromic glazing in multi-zone configuration and one with low-E glazing were modeled. Thermal comfort and sensation of manikin were compared from both rooms at local and overall level. The analysis result showed that multi-zone Electrochromic glazing could significantly improve the thermal comfort levels of manikin model. Analysis result was reported in terms of color-coded manikin and interior solar radiation model for the selected hour that occupant receives direct sunlight penetration.


Electrochromic (EC) technology plays a major role in the development of dynamic smart glazing that can be controlled automatically and modulates transmitted heat and light. EC devices are multilayer systems

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Thermal comfort is defined as “that condition of mind which expresses satisfaction with the thermal environment and is assessed by subjective evaluation (ANSI/ASHRAE Standard 55-2010) Thermal comfort is difficult to

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UC Berkeley Thermal Comfort Model (BCM) has been used to predict thermal comfort for a wide range of solar angles. This multi-segment model predicts skin and core temperatures, sensation and

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SageGlass EC glazing was modeled in three horizontal zones for maximizing the thermal comfort and heat control performance while still admitting sufficient daylight and controlling the sunlight glare. For the

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Scenario 1: Conventional façade with overhang vs. SageGlass

Even in the middle of winter, there is sufficient solar radiation on the southeast elevation in a northern climate (Pennsylvania) to cause

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Conclusion and Future Work

Thermal comfort performance of the EC glazing was compared with low-E glazing in two case studies: conventional façade with overhang facing south-east and simple conventional façade facing west. EC glazing

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Rights and Permissions

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