Neutral daylight illumination with electrochromic glazing: simulation of ‘light mixing’

Electrochromic glazing generally exhibits a shift in spectral transmission as the glass darkens, e.g. causing it to appear blue as it tints. Occupants however are believed to prefer a neutral spectrum of daylight illumination without any pronounced hue. In this paper the authors show that it is possible to maintain a neutral spectrum of illumination with EC glazing under normal operation provided that just a small proportion of the EC glazing is kept in the clear state. Predictions from a theoretical model are compared with measurements of the daylight spectra in an office with EC glazing under various states of tint. The predicted spectra show excellent agreement with the measurements. The theoretical model is further validated using lighting simulation to demonstrate that, under normal operation, illumination from clear and full-tint EC is well-mixed, with that from clear glazing dominating the overall illumination

Evaluation of a mixed method approach for studying user interaction with novel building control technology

Energy-efficient building performance requires sophisticated control systems that are based on realistic occupant behaviour models. To provide robust data for the development of these models, research studies in real-world settings are needed. Yet, such studies are challenging and necessitate careful design in terms of data collection methods and procedures. This paper describes and critiques the design of a mixed methods approach for occupant behaviour research. It reviews the methodology developed for a longitudinal study in a real-world office environment where occupants’ experience with a novel facade technology (electrochromic glazing) was investigated. The methodology integrates objective physical measurements, observational data and self-reported experience data. Using data from one day of the study, this paper illustrates how the different sources can be combined in order to derive an in-depth understanding of the interplay between external daylight conditions, characteristics of the facade technology, occupant interaction with the technology and the resulting occupant experience. It was found that whilst the individual methods may be affected by practical limitations, these can be partially offset by combining physical measurements and observations with self-reported data. The paper critically evaluates the individual techniques, as well as the benefits of their integration and makes recommendations for the design of future occupant behaviour studies in real-world settings

Electrochromic glazing in buildings: A case study

© 2015 Wiley-VCH Verlag GmbH & Co. KGaA. A major application area for electrochromic devices is architectural glazing, particularly that for office buildings which are often highly glazed. This chapter begins with an overview of daylighting in non-residential buildings and explains why the traditional control solutions, for example, blinds, often lead to the under-exploitation of the daylighting potential of the building. It reviews the control of daylight in buildings together with reasons why the traditional methods, for example, venetian blinds, are habitually used in a sub-optimal fashion, often negating the daylight potential afforded by the glazing design. Various types of chromogenic and variable transmission glazing (VTG) are outlined, and the potential for practical use in buildings together with operational factors and performance issues is discussed. The chapter concludes with a description of and preliminary findings from a case study evaluation of a pair of offices spaces in the United Kingdom fitted with EC glazing