A. Luna Navarro
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56 records found
1
Interface design for lighting and shading controls
Device type, position, and system cues influencing user preference and acceptance
Journal article
(2026)
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P. de la Barra, P. Martinez-Alcaraz, E. Brembilla, G. Brager, K. Exss, A. Luna-Navarro
The integration of smart control systems in office buildings can be disruptive when individual preferences and expectations for control interfaces are overlooked. Understanding how human–building interaction influences environmental comfort and acceptance is essential for creating user-centered designs. This study aimed to evaluate the effectiveness of usability testing as an innovative method for assessing building system control interfaces and user interaction with automation. Specifically, we examined user preferences for shading and lighting controls in a controlled office laboratory, varying by “Type of Device” (analog vs. digital), “Position” (wall, desk, or split), and “System Cues” (information richness). In an experimental setting involving 20 participants, we investigated how these factors influence satisfaction and acceptance of automation. Using an adapted Post-Study System Usability Questionnaire (PSSUQ), we evaluated satisfaction with Ease of Use, Reachability, and Information. Findings show that while participants’ initial expectations favored simple analog controls, preferences shifted toward digital, information-rich systems after hands-on interaction. Ordered logistic regression confirmed that Reachability (β=2.317) and Ease of Use (β=1.831) were the strongest predictors of Overall Satisfaction (p<0.001), placing interface position as the primary design characteristic. However, preferences varied by office type: in shared offices, users preferred wall-mounted controls to facilitate shared access and visibility. These insights offer actionable guidance for designing smart control interfaces that enhance user satisfaction, support personal control, and promote greater acceptance of building automation.
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The integration of smart control systems in office buildings can be disruptive when individual preferences and expectations for control interfaces are overlooked. Understanding how human–building interaction influences environmental comfort and acceptance is essential for creating user-centered designs. This study aimed to evaluate the effectiveness of usability testing as an innovative method for assessing building system control interfaces and user interaction with automation. Specifically, we examined user preferences for shading and lighting controls in a controlled office laboratory, varying by “Type of Device” (analog vs. digital), “Position” (wall, desk, or split), and “System Cues” (information richness). In an experimental setting involving 20 participants, we investigated how these factors influence satisfaction and acceptance of automation. Using an adapted Post-Study System Usability Questionnaire (PSSUQ), we evaluated satisfaction with Ease of Use, Reachability, and Information. Findings show that while participants’ initial expectations favored simple analog controls, preferences shifted toward digital, information-rich systems after hands-on interaction. Ordered logistic regression confirmed that Reachability (β=2.317) and Ease of Use (β=1.831) were the strongest predictors of Overall Satisfaction (p<0.001), placing interface position as the primary design characteristic. However, preferences varied by office type: in shared offices, users preferred wall-mounted controls to facilitate shared access and visibility. These insights offer actionable guidance for designing smart control interfaces that enhance user satisfaction, support personal control, and promote greater acceptance of building automation.
Building automation and control systems (BACS) are central to energy performance and occupant comfort in non-residential buildings. Comfort is inherently multi-domain, including thermal, visual, acoustic, and air quality requirements. Multi-domain BACS involves frequent trade-offs across domains when conflicting control actions arise, such as providing glare control versus daylight availability. Yet existing occupant-centric control research treats building services in isolation, and prior multi-domain comfort reviews rarely examine how multi-domain demands are integrated into BACS decision logic across services. We conducted a systematic review of 43 studies to examine how multi-domain occupant demands are represented and operationalized in BACS. Across the evidence base, thermal comfort is universal, while visual and air quality are frequently included. Acoustics is rarely addressed due controllability constraints. Most studies remain unimodal in their demand representation, even when multiple domains are in scope. Integrated BACS implementations are therefore largely built on within-domain formulations. Multimodal demand models that encode cross-domain and combined effects are uncommon and are rarely implemented in integrated BACS. Rule-based strategies dominate multi-domain controllers. Optimization-based and learning-based controllers are also used, but they often rely on fixed weights or reward terms that make trade-offs difficult to interpret. In addition, actuator choice is rarely made explicit when multiple services can achieve the same target state. Future research should benchmark unimodal and multimodal demand formulations under comparable control contexts, extend bottom-up multimodal models beyond thermal and air quality into integrated BACS, especially for façade control, and develop transparent, preference-aware policy designs that make priorities and service actions understandable.
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Building automation and control systems (BACS) are central to energy performance and occupant comfort in non-residential buildings. Comfort is inherently multi-domain, including thermal, visual, acoustic, and air quality requirements. Multi-domain BACS involves frequent trade-offs across domains when conflicting control actions arise, such as providing glare control versus daylight availability. Yet existing occupant-centric control research treats building services in isolation, and prior multi-domain comfort reviews rarely examine how multi-domain demands are integrated into BACS decision logic across services. We conducted a systematic review of 43 studies to examine how multi-domain occupant demands are represented and operationalized in BACS. Across the evidence base, thermal comfort is universal, while visual and air quality are frequently included. Acoustics is rarely addressed due controllability constraints. Most studies remain unimodal in their demand representation, even when multiple domains are in scope. Integrated BACS implementations are therefore largely built on within-domain formulations. Multimodal demand models that encode cross-domain and combined effects are uncommon and are rarely implemented in integrated BACS. Rule-based strategies dominate multi-domain controllers. Optimization-based and learning-based controllers are also used, but they often rely on fixed weights or reward terms that make trade-offs difficult to interpret. In addition, actuator choice is rarely made explicit when multiple services can achieve the same target state. Future research should benchmark unimodal and multimodal demand formulations under comparable control contexts, extend bottom-up multimodal models beyond thermal and air quality into integrated BACS, especially for façade control, and develop transparent, preference-aware policy designs that make priorities and service actions understandable.
Corrigendum to ‘Resilience readiness levels for buildings
Establishing multi-hazard resilience metrics and rating systems’(International Journal of Disaster Risk Reduction, (2025), 128, C, (105746), (S2212420925005709), 10.1016/j.ijdrr.2025.105746)
Journal article
(2026)
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Simona Bianchi, Michele Matteoni, Kyujin Kim, Anna Maria Koniari, Kyra Koning, Alessandra Luna-Navarro, Zhikai Peng, Anna Silva, Mauro Overend, More Authors
The authors wish to replace the flood hazard map in Fig. 11a with an updated map for the Acerra region. The legend has been revised to display only the minimum and maximum flood depth values.(Figure presented) Fig. 11. (a) Flood hazard map for the Acerra region (Pluvial flooding - RCP 8.5 for year 2050, 50th Percentile - 1000 years return period) overlayed on the case study buildings (highlighted in orange).
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The authors wish to replace the flood hazard map in Fig. 11a with an updated map for the Acerra region. The legend has been revised to display only the minimum and maximum flood depth values.(Figure presented) Fig. 11. (a) Flood hazard map for the Acerra region (Pluvial flooding - RCP 8.5 for year 2050, 50th Percentile - 1000 years return period) overlayed on the case study buildings (highlighted in orange).
Building Automation and Control Systems (BACS) enhance energy efficiency in office buildings but often leave occupants dissatisfied, especially in shared offices with diverse indoor environmental preferences. Personal Comfort Models (PCM) capture individual preferences, yet these models can be difficult to apply in shared environments. This study examines whether a generalized personalized modeling would be necessary, or instead aggregated thermal preferences adequately represent individual needs in shared spaces. By mining the ASHRAE Global Thermal Comfort Database II, we analyzed 11 naturally ventilated office buildings spanning four climate zones, each providing 187 to 568 data points of subjective thermal preferences and concurrent environmental measurements. To capture uncertainties in occupant feedback and monitoring, we developed a Bayesian multinomial logistic framework. We compare an aggregated model (all responses together) with a hierarchical (partial-pooling) model having occupant-specific intercepts, using the No‑U‑Turn Sampler for Hamiltonian Monte Carlo. The Widely Applicable Bayesian Information Criterion confirms that hierarchical approach outperforms the aggregated model in every case. In four of the eleven studies, aggregated air temperature ranges satisfied occupants’ demands within a 95% posterior credible interval. Moreover, in most buildings, these temperature ranges aligned well with the majority of occupant preferences, suggesting that prior knowledge of building conditions or occupant variability might reduce the need for highly customized thermal environment. Future research should explore these findings in conditioned buildings and across other indoor environmental quality domains, where greater variability could exist.
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Building Automation and Control Systems (BACS) enhance energy efficiency in office buildings but often leave occupants dissatisfied, especially in shared offices with diverse indoor environmental preferences. Personal Comfort Models (PCM) capture individual preferences, yet these models can be difficult to apply in shared environments. This study examines whether a generalized personalized modeling would be necessary, or instead aggregated thermal preferences adequately represent individual needs in shared spaces. By mining the ASHRAE Global Thermal Comfort Database II, we analyzed 11 naturally ventilated office buildings spanning four climate zones, each providing 187 to 568 data points of subjective thermal preferences and concurrent environmental measurements. To capture uncertainties in occupant feedback and monitoring, we developed a Bayesian multinomial logistic framework. We compare an aggregated model (all responses together) with a hierarchical (partial-pooling) model having occupant-specific intercepts, using the No‑U‑Turn Sampler for Hamiltonian Monte Carlo. The Widely Applicable Bayesian Information Criterion confirms that hierarchical approach outperforms the aggregated model in every case. In four of the eleven studies, aggregated air temperature ranges satisfied occupants’ demands within a 95% posterior credible interval. Moreover, in most buildings, these temperature ranges aligned well with the majority of occupant preferences, suggesting that prior knowledge of building conditions or occupant variability might reduce the need for highly customized thermal environment. Future research should explore these findings in conditioned buildings and across other indoor environmental quality domains, where greater variability could exist.
The provision of personalized air velocity for occupants in open-plan offices during summer has the potential to enhance comfort, productivity and energy efficiency, by integrating Personalised Environmental Control Systems (PECS) in open plan offices. However, the design and integration of PECS in open space offices is often hindered by several design challenges, while the user-centred design of PECS requires the simultaneous understanding of several human requirements from a multi-domain perspective, ranging from ergonomics disciplines to indoor climate sciences. First, this study conducted interviews with practitioners from the indoor climate and office design sectors to evaluate the requirements of several stakeholders involved in the design of office spaces. Secondly, interviews with end-users are conducted to evaluate the key factors influencing user satisfaction with PECS. On the basis of these results, a framework is proposed to support the design of occupant-centred systems for increasing air movement in office spaces in a personalized and local manner. The framework identifies essential design factors and criteria, distinguishing between must-have and optional elements in user-centred PECS. Overall, this research contributes to the advancement of personalized environmental control systems, offering insights applicable to various workplace settings and climatic conditions.
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The provision of personalized air velocity for occupants in open-plan offices during summer has the potential to enhance comfort, productivity and energy efficiency, by integrating Personalised Environmental Control Systems (PECS) in open plan offices. However, the design and integration of PECS in open space offices is often hindered by several design challenges, while the user-centred design of PECS requires the simultaneous understanding of several human requirements from a multi-domain perspective, ranging from ergonomics disciplines to indoor climate sciences. First, this study conducted interviews with practitioners from the indoor climate and office design sectors to evaluate the requirements of several stakeholders involved in the design of office spaces. Secondly, interviews with end-users are conducted to evaluate the key factors influencing user satisfaction with PECS. On the basis of these results, a framework is proposed to support the design of occupant-centred systems for increasing air movement in office spaces in a personalized and local manner. The framework identifies essential design factors and criteria, distinguishing between must-have and optional elements in user-centred PECS. Overall, this research contributes to the advancement of personalized environmental control systems, offering insights applicable to various workplace settings and climatic conditions.
Conference paper
(2026)
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Eleni Chatzi Nestoros, Pablo Martinez-Alcaraz, Alejandro Fuentes, Juan Diego Blanco Cadena, Michela Turrin, Tiziana Poli, Alessandra Luna-Navarro
Urbanization and climate change have intensified urban heat island effects, significantly affecting outdoor thermal comfort (OTC) in cities. Traditional methods of assessing the influence of urban environments on OTC often rely heavily on computational simulations, neglecting the integration of user-centric data and comprehensive environmental monitoring. This study investigates the relationship between microclimatic conditions, thermal sensation, and human preferences to identify the key factors influencing outdoor thermal comfort. Using the Acquabella district in Milan as a case study, the research adopts a cross-examination approach that integrates qualitative and quantitative assessments to evaluate outdoor thermal conditions. The methodology combines user-centered participatory approaches, including a workshop and an online survey, to identify critical intervention areas and factors contributing to thermal discomfort. Thermal Sensation Votes (TSV) are collected and analyzed in QGIS, highlighting significant environmental and psychological factors influencing user perception. Preliminary simulations using SOLWEIG are employed to cross-examine the results, identifying spaces with varying levels of thermal comfort. This study underscores the value of combining objective and subjective measures to pinpoint areas of critical environmental quality and optimize decision-making processes. By leveraging user data, the methodology reduces computational demands while offering actionable insights for urban health. The approach is scalable to different urban contexts, fostering the development of resilient and climate-adaptive environments.
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Urbanization and climate change have intensified urban heat island effects, significantly affecting outdoor thermal comfort (OTC) in cities. Traditional methods of assessing the influence of urban environments on OTC often rely heavily on computational simulations, neglecting the integration of user-centric data and comprehensive environmental monitoring. This study investigates the relationship between microclimatic conditions, thermal sensation, and human preferences to identify the key factors influencing outdoor thermal comfort. Using the Acquabella district in Milan as a case study, the research adopts a cross-examination approach that integrates qualitative and quantitative assessments to evaluate outdoor thermal conditions. The methodology combines user-centered participatory approaches, including a workshop and an online survey, to identify critical intervention areas and factors contributing to thermal discomfort. Thermal Sensation Votes (TSV) are collected and analyzed in QGIS, highlighting significant environmental and psychological factors influencing user perception. Preliminary simulations using SOLWEIG are employed to cross-examine the results, identifying spaces with varying levels of thermal comfort. This study underscores the value of combining objective and subjective measures to pinpoint areas of critical environmental quality and optimize decision-making processes. By leveraging user data, the methodology reduces computational demands while offering actionable insights for urban health. The approach is scalable to different urban contexts, fostering the development of resilient and climate-adaptive environments.
Conference paper
(2026)
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E.R.L. Lenarduzzi, S. Maniatis, Alessandra Luna-Navarro, M.U.J. Peeters, Hadrien Heuclin, Francois Guillemot, R.C. Hartwell
The reuse and high-value recovery of architectural glazing offer significant potential to reduce waste and minimize the environmental impact of the glass sector. Still, there is a lack of a standardised approach to support decisions in environmentally efficient renovation pathways that integrate all life-cycle stages and account for varying glazing types, geographical locations, and service-life dynamics. This study develops a novel assessment framework to quantify the environmental and financial trade-offs of alternative glass recovery pathways. The computational framework incorporates life-cycle embodied carbon analyses across material recovery scenarios and temporal energy simulations parameterized by panel geometry, build-up, window condition, and collection site. The framework was applied to six reference glazing products in residential and commercial case studies located in France. It was found that carbon payback periods range from under five years for deteriorated early-generation glazing to well beyond 25 years for non-deteriorated products or products subject to high-infiltration conditions, highlighting the importance of existing building condition in guiding intervention decisions. Under current market conditions, it is shown that despite their embodied carbon benefits, reuse and remanufacturing both incur substantially higher 30-year net present value costs (EUR) compared to recycling recovered glazing and installing new high performance IGUs.
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The reuse and high-value recovery of architectural glazing offer significant potential to reduce waste and minimize the environmental impact of the glass sector. Still, there is a lack of a standardised approach to support decisions in environmentally efficient renovation pathways that integrate all life-cycle stages and account for varying glazing types, geographical locations, and service-life dynamics. This study develops a novel assessment framework to quantify the environmental and financial trade-offs of alternative glass recovery pathways. The computational framework incorporates life-cycle embodied carbon analyses across material recovery scenarios and temporal energy simulations parameterized by panel geometry, build-up, window condition, and collection site. The framework was applied to six reference glazing products in residential and commercial case studies located in France. It was found that carbon payback periods range from under five years for deteriorated early-generation glazing to well beyond 25 years for non-deteriorated products or products subject to high-infiltration conditions, highlighting the importance of existing building condition in guiding intervention decisions. Under current market conditions, it is shown that despite their embodied carbon benefits, reuse and remanufacturing both incur substantially higher 30-year net present value costs (EUR) compared to recycling recovered glazing and installing new high performance IGUs.
Journal article
(2026)
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Alvaro Balderrama, Alessandra Luna-Navarro, Jian Kang, Hussam Al Basha, Eric Verschuur, Daniel Arztmann, Ulrich Knaack
As automation is progressively more present in buildings, it is important to understand its impact on people’s experience of urban environments. This case study investigated how one automated shading system with motorized venetian blinds affects sound perception of the acoustic environment in the immediate outdoor surroundings of a university campus building in Detmold, Germany. Procedures of ISO 12913 series for soundscape research were followed to conduct acoustic measurements and derive psychoacoustic indicators. Additionally, soundwalks involving 41 participants and a laboratory study using immersive virtual reality (VR) with 34 participants were conducted to assess how individuals perceive the acoustic environment. The results show that the operation of automated blinds increases sound levels above reference thresholds at short distances, and has a consistent effect on the soundscape, shifting it from pleasant and calm to annoying and chaotic. These trends are notable in both on-site and laboratory data. Additionally, when participants evaluated the soundscape in direct visual connection with the operating façade shading system, they perceived the sounds to be less chaotic than when they were not seeing the façade. These findings highlight that automated buildings and façades are active sound sources capable of influencing environmental quality through acoustic and non-acoustic effects; therefore, their influence on the soundscape should be considered within performance assessments, smart/automation policy, and sustainability frameworks.
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As automation is progressively more present in buildings, it is important to understand its impact on people’s experience of urban environments. This case study investigated how one automated shading system with motorized venetian blinds affects sound perception of the acoustic environment in the immediate outdoor surroundings of a university campus building in Detmold, Germany. Procedures of ISO 12913 series for soundscape research were followed to conduct acoustic measurements and derive psychoacoustic indicators. Additionally, soundwalks involving 41 participants and a laboratory study using immersive virtual reality (VR) with 34 participants were conducted to assess how individuals perceive the acoustic environment. The results show that the operation of automated blinds increases sound levels above reference thresholds at short distances, and has a consistent effect on the soundscape, shifting it from pleasant and calm to annoying and chaotic. These trends are notable in both on-site and laboratory data. Additionally, when participants evaluated the soundscape in direct visual connection with the operating façade shading system, they perceived the sounds to be less chaotic than when they were not seeing the façade. These findings highlight that automated buildings and façades are active sound sources capable of influencing environmental quality through acoustic and non-acoustic effects; therefore, their influence on the soundscape should be considered within performance assessments, smart/automation policy, and sustainability frameworks.
Conference paper
(2026)
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Pedro de la Barra, Pablo Martinez-Alcaraz, Eleonora Brembilla, Alessandra Luna-Navarro
The integration of smart control systems in office buildings often neglects individual expectations and preferences, especially when occupants do not have personal control over their environment. While existing research has advanced personalized comfort models, simulated energy-use behaviors, and quantitative methods for occupant-centric building design, it often overlooks the critical role of personalized control interfaces. These interfaces are essential for integrating occupants into the operable building systems. This study investigates occupant preferences for personal control after experiencing different building control interfaces for lighting and roller shades in an office environment. Using a usability testing approach, 20 participants were involved in brief interaction sessions to evaluate how interface type (digital vs. analogue), position (wall-mounted vs. desk-mounted), and level of information influence occupants’ satisfaction. Additionally, we explored whether participants’ preferences for indoor environmental quality conditions correspond with their reported satisfaction with building control interfaces. Results show that interface placement significantly influences user preference, beyond ease of access. While participants initially favored analogue controls and manual operation, exposure to digital and automated systems led to greater acceptance, particularly when these systems provided clear information and maintained personal control. These findings underscore the importance of actual experiences with system interfaces in understanding occupant preferences and acceptance with building technologies, which is key for occupant-centered design in building control.
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The integration of smart control systems in office buildings often neglects individual expectations and preferences, especially when occupants do not have personal control over their environment. While existing research has advanced personalized comfort models, simulated energy-use behaviors, and quantitative methods for occupant-centric building design, it often overlooks the critical role of personalized control interfaces. These interfaces are essential for integrating occupants into the operable building systems. This study investigates occupant preferences for personal control after experiencing different building control interfaces for lighting and roller shades in an office environment. Using a usability testing approach, 20 participants were involved in brief interaction sessions to evaluate how interface type (digital vs. analogue), position (wall-mounted vs. desk-mounted), and level of information influence occupants’ satisfaction. Additionally, we explored whether participants’ preferences for indoor environmental quality conditions correspond with their reported satisfaction with building control interfaces. Results show that interface placement significantly influences user preference, beyond ease of access. While participants initially favored analogue controls and manual operation, exposure to digital and automated systems led to greater acceptance, particularly when these systems provided clear information and maintained personal control. These findings underscore the importance of actual experiences with system interfaces in understanding occupant preferences and acceptance with building technologies, which is key for occupant-centered design in building control.
Conference paper
(2026)
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P. de la Barra, M. S. Khanie, A. Luna-Navarro, P. Martinez-Alcaraz, D. Al Assaad, E. M. Barrett, G. Chinazzo, Z. Deng, B. Dong, More Authors
Buildings are striving to be both energy-efficient and occupant-centered. Personalized systems for lighting and dynamic fenestration systems, e.g., switchable glazing, are emerging as a key solution. These systems, called Personalized Environmental Control Systems (PECS), allow individuals to adjust their immediate environment without impacting others. While PECS initially focused on temperature and air quality, this study explores the potential for the luminous environment, introducing the concept of Visual PECS.
Daylighting and lighting controls build on a long history of personalized systems and methods, from prehistoric torches to adjustable desk lamps. They allow for individual control over (day)light spectrum and intensity, catering to personal needs and promoting circadian health and cellular processes (i.e., photobiomodulation). Additionally, they can reduce glare and improve visual comfort, leading to increased productivity and well-being. Despite this long history, studies formulating “personalized environmental control systems” (PECS) in the daylighting and lighting domain are rare. In this paper, we present preliminary results from a comprehensive review, where 31 papers were identified from an initial pool of 5,238. The findings highlighted two key benefits. First, semi-automated PECS offer the highest energy savings, highlighting the importance of understanding the relationship between users and automation. Secondly, PECS provides improved occupant experience since the ability to control their environment empowers occupants, leading to increased comfort and productivity. Overall, PECS have the potential to facilitate individual control over lighting and visual parameters, ultimately enhancing visual comfort and satisfaction as well as beyond-visual well-being. Our research builds upon the ongoing work of IEA EBC - Annex 87, which investigates the energy and environmental benefits of PECS. ...
Daylighting and lighting controls build on a long history of personalized systems and methods, from prehistoric torches to adjustable desk lamps. They allow for individual control over (day)light spectrum and intensity, catering to personal needs and promoting circadian health and cellular processes (i.e., photobiomodulation). Additionally, they can reduce glare and improve visual comfort, leading to increased productivity and well-being. Despite this long history, studies formulating “personalized environmental control systems” (PECS) in the daylighting and lighting domain are rare. In this paper, we present preliminary results from a comprehensive review, where 31 papers were identified from an initial pool of 5,238. The findings highlighted two key benefits. First, semi-automated PECS offer the highest energy savings, highlighting the importance of understanding the relationship between users and automation. Secondly, PECS provides improved occupant experience since the ability to control their environment empowers occupants, leading to increased comfort and productivity. Overall, PECS have the potential to facilitate individual control over lighting and visual parameters, ultimately enhancing visual comfort and satisfaction as well as beyond-visual well-being. Our research builds upon the ongoing work of IEA EBC - Annex 87, which investigates the energy and environmental benefits of PECS. ...
Buildings are striving to be both energy-efficient and occupant-centered. Personalized systems for lighting and dynamic fenestration systems, e.g., switchable glazing, are emerging as a key solution. These systems, called Personalized Environmental Control Systems (PECS), allow individuals to adjust their immediate environment without impacting others. While PECS initially focused on temperature and air quality, this study explores the potential for the luminous environment, introducing the concept of Visual PECS.
Daylighting and lighting controls build on a long history of personalized systems and methods, from prehistoric torches to adjustable desk lamps. They allow for individual control over (day)light spectrum and intensity, catering to personal needs and promoting circadian health and cellular processes (i.e., photobiomodulation). Additionally, they can reduce glare and improve visual comfort, leading to increased productivity and well-being. Despite this long history, studies formulating “personalized environmental control systems” (PECS) in the daylighting and lighting domain are rare. In this paper, we present preliminary results from a comprehensive review, where 31 papers were identified from an initial pool of 5,238. The findings highlighted two key benefits. First, semi-automated PECS offer the highest energy savings, highlighting the importance of understanding the relationship between users and automation. Secondly, PECS provides improved occupant experience since the ability to control their environment empowers occupants, leading to increased comfort and productivity. Overall, PECS have the potential to facilitate individual control over lighting and visual parameters, ultimately enhancing visual comfort and satisfaction as well as beyond-visual well-being. Our research builds upon the ongoing work of IEA EBC - Annex 87, which investigates the energy and environmental benefits of PECS.
Daylighting and lighting controls build on a long history of personalized systems and methods, from prehistoric torches to adjustable desk lamps. They allow for individual control over (day)light spectrum and intensity, catering to personal needs and promoting circadian health and cellular processes (i.e., photobiomodulation). Additionally, they can reduce glare and improve visual comfort, leading to increased productivity and well-being. Despite this long history, studies formulating “personalized environmental control systems” (PECS) in the daylighting and lighting domain are rare. In this paper, we present preliminary results from a comprehensive review, where 31 papers were identified from an initial pool of 5,238. The findings highlighted two key benefits. First, semi-automated PECS offer the highest energy savings, highlighting the importance of understanding the relationship between users and automation. Secondly, PECS provides improved occupant experience since the ability to control their environment empowers occupants, leading to increased comfort and productivity. Overall, PECS have the potential to facilitate individual control over lighting and visual parameters, ultimately enhancing visual comfort and satisfaction as well as beyond-visual well-being. Our research builds upon the ongoing work of IEA EBC - Annex 87, which investigates the energy and environmental benefits of PECS.
Resilience Readiness Levels for buildings
Establishing multi-hazard resilience metrics and rating systems
Journal article
(2025)
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Simona Bianchi, Michele Matteoni, Kyujin Kim, Anna Maria Koniari, Kyra Koning, Alessandra Luna-Navarro, Zhikai Peng, Anna Silva, Mauro Overend, More authors...
The built environment is vulnerable to climate-induced extreme events and natural disasters, which are repeatedly exposing communities to severe consequences and market disruptions. In response, the construction industry is developing resilient technologies for buildings, but the proposed solutions are often not cost-effective, rarely eco-friendly and typically fail to address multiple hazards present in many locations. These shortcomings stem from the absence of a clearly defined framework for quantifying holistic multi-hazard resilience. As a result, investment decisions are ill-informed and technical solutions are sub-optimal. This paper redresses this issue by proposing quantitative indicators and introducing the Resilience Readiness Levels to assess the resilience of buildings, considering multi-domain factors (physical, social, economic, environmental) in single or multi-hazard contexts (heat, seismic, wind, flood). The proposed resilience indices and calculation methods are based on a diverse set of scientific literature and real-world practices, and are demonstrated on Dutch and Italian urban blocks with different local hazards and building layouts. The results show that the multi-domain resilience approach can support informed early-stage building design and retrofit decision-making for single hazards, while aiding prioritization and intervention planning for improving building disaster preparedness in multi-hazard scenarios.
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The built environment is vulnerable to climate-induced extreme events and natural disasters, which are repeatedly exposing communities to severe consequences and market disruptions. In response, the construction industry is developing resilient technologies for buildings, but the proposed solutions are often not cost-effective, rarely eco-friendly and typically fail to address multiple hazards present in many locations. These shortcomings stem from the absence of a clearly defined framework for quantifying holistic multi-hazard resilience. As a result, investment decisions are ill-informed and technical solutions are sub-optimal. This paper redresses this issue by proposing quantitative indicators and introducing the Resilience Readiness Levels to assess the resilience of buildings, considering multi-domain factors (physical, social, economic, environmental) in single or multi-hazard contexts (heat, seismic, wind, flood). The proposed resilience indices and calculation methods are based on a diverse set of scientific literature and real-world practices, and are demonstrated on Dutch and Italian urban blocks with different local hazards and building layouts. The results show that the multi-domain resilience approach can support informed early-stage building design and retrofit decision-making for single hazards, while aiding prioritization and intervention planning for improving building disaster preparedness in multi-hazard scenarios.
Integrating heat and seismic risk
A multi-objective decision-making approach for facade retrofit design
Conference paper
(2025)
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Kyujin Kim, Simone D’Amore, Alessandra Luna-Navarro, Thaleia Konstantinou, Mauro Overend, Stefano Pampanin, Simona Bianchi
Current multi-hazard risk approaches in seismic engineering primarily focus on structural performance under hazards such as earthquakes, floods, and wind. Despite the distinct risk due to their direct impact on human health, heatwaves receive limited consideration. This unbalanced and fragmented approach is particularly noticeable in facade retrofit design, which has a significant influence on both structural vulnerability during earthquakes and indoor thermal conditions during heatwaves. In this case, integrating seismic and heat risk considerations would help balance performance trade-offs across both domains and assist designers in the selection and combination of technologies that are effective under seismic and heatwave conditions. This study therefore proposes a simulation-based multi-objective methodology for facade retrofit decision making. The suggested approach is demonstrated through a case study: a reinforced concrete building retrofitted using a timber rocking-dissipative external exoskeleton and precast concrete sandwich facade panels. Key facade design parameters-component capacity and dimensioning-were varied to generate a multivariate response for both seismic and thermal performance. The simulation results revealed two challenges for optimization: a limited sample size and nonlinear relationships between design inputs and performance outcomes. To address both, a multivariate regression was applied within segmented performance ranges, defined by breakpoints where the relationship between parameters and performance shifted. The resulting segmented multivariate model enabled the identification of optimal technology combinations within specific performance ranges and the generation of multiple Pareto fronts. This broadened the viable solution space and better supported project-specific trade-off decisions.
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Current multi-hazard risk approaches in seismic engineering primarily focus on structural performance under hazards such as earthquakes, floods, and wind. Despite the distinct risk due to their direct impact on human health, heatwaves receive limited consideration. This unbalanced and fragmented approach is particularly noticeable in facade retrofit design, which has a significant influence on both structural vulnerability during earthquakes and indoor thermal conditions during heatwaves. In this case, integrating seismic and heat risk considerations would help balance performance trade-offs across both domains and assist designers in the selection and combination of technologies that are effective under seismic and heatwave conditions. This study therefore proposes a simulation-based multi-objective methodology for facade retrofit decision making. The suggested approach is demonstrated through a case study: a reinforced concrete building retrofitted using a timber rocking-dissipative external exoskeleton and precast concrete sandwich facade panels. Key facade design parameters-component capacity and dimensioning-were varied to generate a multivariate response for both seismic and thermal performance. The simulation results revealed two challenges for optimization: a limited sample size and nonlinear relationships between design inputs and performance outcomes. To address both, a multivariate regression was applied within segmented performance ranges, defined by breakpoints where the relationship between parameters and performance shifted. The resulting segmented multivariate model enabled the identification of optimal technology combinations within specific performance ranges and the generation of multiple Pareto fronts. This broadened the viable solution space and better supported project-specific trade-off decisions.
Review
(2025)
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María Victoria Dávalos Quevedo, Alessandra Luna-Navarro, Uta Pottgiesser, Ulrich Blum
Occupant satisfaction in office spaces is a critical factor influencing occupant’s productivity, satisfaction and overall workplace experience. This systematic review examines the methodologies and approaches used to assess occupant satisfaction with office space design, identifying key evaluation tools and research trends. The study explores the extent to which existing methodologies integrate environmental, spatial and design factors to provide a comprehensive understanding of user experience. Additionally, it highlights the limitations in current assessment tools, including the lack of standardised frameworks for capturing occupant feedback at different stages of the design process. The findings suggest a growing shift towards data-driven and real-time feedback mechanisms to enhance workplace adaptability. By synthesising existing research, this review aims to provide insights for designers, facility managers and policymakers to refine evaluation methods and integrate occupant-centric strategies into office space planning.
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Occupant satisfaction in office spaces is a critical factor influencing occupant’s productivity, satisfaction and overall workplace experience. This systematic review examines the methodologies and approaches used to assess occupant satisfaction with office space design, identifying key evaluation tools and research trends. The study explores the extent to which existing methodologies integrate environmental, spatial and design factors to provide a comprehensive understanding of user experience. Additionally, it highlights the limitations in current assessment tools, including the lack of standardised frameworks for capturing occupant feedback at different stages of the design process. The findings suggest a growing shift towards data-driven and real-time feedback mechanisms to enhance workplace adaptability. By synthesising existing research, this review aims to provide insights for designers, facility managers and policymakers to refine evaluation methods and integrate occupant-centric strategies into office space planning.
Additive manufacturing with varying material properties of thermosetting reactive polymers
A framework and comparison of different modes for implementing material transitions
Additive Manufacturing with Varying Material Properties enables controlled spatial variation of material properties in 3D-printed components, facilitating custom-tailored characteristics, added functionalities and reduced assembly processes. To promote this approach in building façade applications, this paper presents a novel framework for Additive Manufacturing with varying material properties using a thermosetting reactive polymer, specifically polyurethane. By dynamically changing the polyurethane’s chemical composition, the material properties can be precisely controlled. The framework’s individual aspects, including the material, hardware setup and computational system, are described in detail. Additionally, the research explores the implementation of material transitions with this framework, highlighting three different modes (horizontal, vertical and multi plane) and their impact on print time and material consumption. The paper concludes by discussing the potential of this approach for building façade applications, addressing current challenges and outlining future research directions.
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Additive Manufacturing with Varying Material Properties enables controlled spatial variation of material properties in 3D-printed components, facilitating custom-tailored characteristics, added functionalities and reduced assembly processes. To promote this approach in building façade applications, this paper presents a novel framework for Additive Manufacturing with varying material properties using a thermosetting reactive polymer, specifically polyurethane. By dynamically changing the polyurethane’s chemical composition, the material properties can be precisely controlled. The framework’s individual aspects, including the material, hardware setup and computational system, are described in detail. Additionally, the research explores the implementation of material transitions with this framework, highlighting three different modes (horizontal, vertical and multi plane) and their impact on print time and material consumption. The paper concludes by discussing the potential of this approach for building façade applications, addressing current challenges and outlining future research directions.
Conference paper
(2025)
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Alessandra Luna-Navarro, Andrea Welti, Pedro de la Barra, Pablo Martinez-Alcaraz, Matteo Porta
The Smart Readiness Indicator (SRI), introduced by the European Union in 2018, assesses a building’s capacity to accommodate smart-ready services. This evaluation focuses on optimizing energy efficiency, aligning operations with occupant needs, and responding to signals from the grid. Previous studies have evaluated SRI feasibility in various locations and retrofit scenarios, estimating the costs associated with implementing smart technologies in existing European buildings. However, the specific impact of digitizing distinct building services on SRI scores remains unexplored. Particularly, adaptive façade technologies show potential in enhancing overall building performance, being worthy to understand how these services influence the smart readiness rating of buildings. This study investigates the impact of adaptive façade technologies on SRI scores and user satisfaction. A case study of an office building in Delft (The Netherlands) was selected to assess the impact of smart technologies on energy efficiency and comfort. This paper shows preliminary results from the pre-intervention phase, where the SRI was calculated for both the baseline condition and a scenario with the highest possible level of smart services for the building envelope. The results from the SRI methodology showed an increase of approximately 4% in energy efficiency and 15% in terms of energy flexibility. In addition, the SRI predicts similar improvements in user convenience, information, health & well-being, but only 4% in user comfort. This was confirmed by the assessments on user perception and preferences. Users reported to be “slightly satisfied” with several comfort domains. Additionally, several users considered better control of external shadings very important, which was currently reported as very disruptive by users. This preliminary finding shows potential for smart services applied at the façade level to improve user satisfaction if aspects of interaction and convenience are adequately addressed. Post-intervention phase data is now required to confirm these preliminary findings.
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The Smart Readiness Indicator (SRI), introduced by the European Union in 2018, assesses a building’s capacity to accommodate smart-ready services. This evaluation focuses on optimizing energy efficiency, aligning operations with occupant needs, and responding to signals from the grid. Previous studies have evaluated SRI feasibility in various locations and retrofit scenarios, estimating the costs associated with implementing smart technologies in existing European buildings. However, the specific impact of digitizing distinct building services on SRI scores remains unexplored. Particularly, adaptive façade technologies show potential in enhancing overall building performance, being worthy to understand how these services influence the smart readiness rating of buildings. This study investigates the impact of adaptive façade technologies on SRI scores and user satisfaction. A case study of an office building in Delft (The Netherlands) was selected to assess the impact of smart technologies on energy efficiency and comfort. This paper shows preliminary results from the pre-intervention phase, where the SRI was calculated for both the baseline condition and a scenario with the highest possible level of smart services for the building envelope. The results from the SRI methodology showed an increase of approximately 4% in energy efficiency and 15% in terms of energy flexibility. In addition, the SRI predicts similar improvements in user convenience, information, health & well-being, but only 4% in user comfort. This was confirmed by the assessments on user perception and preferences. Users reported to be “slightly satisfied” with several comfort domains. Additionally, several users considered better control of external shadings very important, which was currently reported as very disruptive by users. This preliminary finding shows potential for smart services applied at the façade level to improve user satisfaction if aspects of interaction and convenience are adequately addressed. Post-intervention phase data is now required to confirm these preliminary findings.
As cities continue to expand and densify, understanding how buildings affect people’s perception and experience of the acoustic environment in context becomes more relevant. This paper presents a conceptual framework of the influence of façades on the urban soundscape, based on the ISO 12913 series, in order to analyze the three main elements of the soundscape: people, acoustic environment and context, along with façade as a fourth element. The methodology included literature review, as well as an exploration of the ISO 12913 methods for soundscape assessment via soundwalks and laboratory experiments involving a total of forty-three (n = 43) participants. The results provide a promising framework for façade analysis to progress toward the integration of human-centered approaches into the field of façade acoustics and complement current building physics practice.
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As cities continue to expand and densify, understanding how buildings affect people’s perception and experience of the acoustic environment in context becomes more relevant. This paper presents a conceptual framework of the influence of façades on the urban soundscape, based on the ISO 12913 series, in order to analyze the three main elements of the soundscape: people, acoustic environment and context, along with façade as a fourth element. The methodology included literature review, as well as an exploration of the ISO 12913 methods for soundscape assessment via soundwalks and laboratory experiments involving a total of forty-three (n = 43) participants. The results provide a promising framework for façade analysis to progress toward the integration of human-centered approaches into the field of façade acoustics and complement current building physics practice.
Indoor Air and Thermal Quality in School Buildings
Demonstration of BIM-Integrated IoT Window Signaling System
Conference paper
(2025)
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Alessandro D’Amico, Federico Fiume, Pedro de la Barra, Alessandra Luna-Navarro
Indoor Environmental Quality (IEQ) plays a crucial role in the health, well-being, and cognitive performance of students in school environments. This study presents the integration of Building Information Modeling (BIM) and Internet of Things (IoT) sensors for real-time IEQ monitoring and dynamic ventilation control. A BIM-integrated window signaling system was developed using visual programming to process real-time sensor data and provide feedback on optimal window operation times. The methodology consisted of five phases: (1) development of a BIM model of the case study and calculation of window opening time, (2) on-site deployment of an IoT sensor system, (3) integration of real-time environmental data into the BIM model, (4) generation of a continuously updated digital twin for IEQ assessment, and (5) comparison between calculated ventilation times and measured environmental parameters. The system was tested in two classrooms of a school in Rome, Italy, where temperature and CO₂ concentration were continuously monitored. The results indicate that the calculated ventilation schedules effectively maintained indoor temperatures within recommended thresholds. However, CO₂ levels frequently exceeded the guide value threshold in one classroom, revealing discrepancies between the expected and actual window opening behaviors of occupants. The study underscores the role of occupant compliance in ventilation effectiveness and demonstrates how BIM can function as a dynamic decision-support tool by integrating real-time environmental data, automated parameter updates, and graphical trend visualization.
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Indoor Environmental Quality (IEQ) plays a crucial role in the health, well-being, and cognitive performance of students in school environments. This study presents the integration of Building Information Modeling (BIM) and Internet of Things (IoT) sensors for real-time IEQ monitoring and dynamic ventilation control. A BIM-integrated window signaling system was developed using visual programming to process real-time sensor data and provide feedback on optimal window operation times. The methodology consisted of five phases: (1) development of a BIM model of the case study and calculation of window opening time, (2) on-site deployment of an IoT sensor system, (3) integration of real-time environmental data into the BIM model, (4) generation of a continuously updated digital twin for IEQ assessment, and (5) comparison between calculated ventilation times and measured environmental parameters. The system was tested in two classrooms of a school in Rome, Italy, where temperature and CO₂ concentration were continuously monitored. The results indicate that the calculated ventilation schedules effectively maintained indoor temperatures within recommended thresholds. However, CO₂ levels frequently exceeded the guide value threshold in one classroom, revealing discrepancies between the expected and actual window opening behaviors of occupants. The study underscores the role of occupant compliance in ventilation effectiveness and demonstrates how BIM can function as a dynamic decision-support tool by integrating real-time environmental data, automated parameter updates, and graphical trend visualization.
Journal article
(2025)
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Simone Torresin, Larissa Pereira de Souza, Seda Yuksel Dicle, Douaa Al-Assaad, Francesco Aletta, Alvaro Balderrama, Mariya P. Bivolarova, Pyoung Jik Lee, Alessandra Luna Navarro, More authors...
Personalised Environmental Control Systems (PECS) enable occupants to locally adjust environmental parameters without affecting others. Rooted in the fields of thermal and air quality management, this approach is key for enhancing satisfaction and well-being in the built environment by empowering occupants to control their immediate surroundings. Moreover, it offers energy-saving potential by optimizing conditions in targeted areas rather than across the entire environment. Within the framework of the IEA EBC Annex 87, the concept was explored for the first time in the acoustic domain. After defining Acoustic PECS, a systematic review according to PRISMA guidelines was conducted to unpack (1) technologies in the literature aligning with this concept; (2) their impact on occupants; and (3) current limitations. The literature search, conducted on Scopus, Web of Science, APA, and PubMed, included field or laboratory studies assessing systems enabling local acoustic control in settings that are relevant for office environments. Review papers, medical device studies, and reports without insights on occupant impact were excluded. Thirty-eight studies were selected, covering active and passive systems, building-attached, furniture-integrated, and wearable devices. The qualitative analysis highlighted potential positive effects in challenging acoustic environments, including reduced annoyance, improved work performance, masking or cancellation of intrusive noises, and enhancements in short-term memory, among other benefits, despite existing technological and methodological limitations. The evidence collected is constrained by the limited number of identified studies and methodological gaps stemming from the relatively wide focus of the studies where such devices were investigated. The definition of Acoustic PECS provides a foundation for future research, guiding the development of these systems and fostering high-quality and consistent evidence of their impacts.
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Personalised Environmental Control Systems (PECS) enable occupants to locally adjust environmental parameters without affecting others. Rooted in the fields of thermal and air quality management, this approach is key for enhancing satisfaction and well-being in the built environment by empowering occupants to control their immediate surroundings. Moreover, it offers energy-saving potential by optimizing conditions in targeted areas rather than across the entire environment. Within the framework of the IEA EBC Annex 87, the concept was explored for the first time in the acoustic domain. After defining Acoustic PECS, a systematic review according to PRISMA guidelines was conducted to unpack (1) technologies in the literature aligning with this concept; (2) their impact on occupants; and (3) current limitations. The literature search, conducted on Scopus, Web of Science, APA, and PubMed, included field or laboratory studies assessing systems enabling local acoustic control in settings that are relevant for office environments. Review papers, medical device studies, and reports without insights on occupant impact were excluded. Thirty-eight studies were selected, covering active and passive systems, building-attached, furniture-integrated, and wearable devices. The qualitative analysis highlighted potential positive effects in challenging acoustic environments, including reduced annoyance, improved work performance, masking or cancellation of intrusive noises, and enhancements in short-term memory, among other benefits, despite existing technological and methodological limitations. The evidence collected is constrained by the limited number of identified studies and methodological gaps stemming from the relatively wide focus of the studies where such devices were investigated. The definition of Acoustic PECS provides a foundation for future research, guiding the development of these systems and fostering high-quality and consistent evidence of their impacts.
The increase in carbon emissions has contributed to rising global temperatures, necessitating higher energy consumption in buildings to maintain thermal comfort during the summer months. The building envelope, as the protective layer of a building, plays a critical role in maintaining indoor comfort and dictating building energy use. However, when assessing the performance of the building envelope, occupant interaction is poorly considered. This study investigates the impact of occupant façade interaction when evaluating alternative façade solutions for thermal comfort in summer season. Occupant behaviour models, specifically window operation models, are identified and implemented to assess their impact on indoor comfort and air quality. This is done by first identifying façade archetypes and generating scenarios with selected occupant behavior models. The results revealed that occupant interaction with windows significantly impact internal air temperatures and thermal comfort, while alternative façade solutions have a relatively lower impact. Largest ventilation areas were associated with lower air temperatures. Consequently, the number of discomfort hours are also lower in scenarios with occupant interaction compared to without. The impact of the façade ventilation area, window-to-wall ratio and thermal mass was more relevant in the scenarios where windows were always closed. The findings of this study can serve as a foundation for the development of strategies that promote occupant interaction with the façade which can lead to reduced building energy demand.
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The increase in carbon emissions has contributed to rising global temperatures, necessitating higher energy consumption in buildings to maintain thermal comfort during the summer months. The building envelope, as the protective layer of a building, plays a critical role in maintaining indoor comfort and dictating building energy use. However, when assessing the performance of the building envelope, occupant interaction is poorly considered. This study investigates the impact of occupant façade interaction when evaluating alternative façade solutions for thermal comfort in summer season. Occupant behaviour models, specifically window operation models, are identified and implemented to assess their impact on indoor comfort and air quality. This is done by first identifying façade archetypes and generating scenarios with selected occupant behavior models. The results revealed that occupant interaction with windows significantly impact internal air temperatures and thermal comfort, while alternative façade solutions have a relatively lower impact. Largest ventilation areas were associated with lower air temperatures. Consequently, the number of discomfort hours are also lower in scenarios with occupant interaction compared to without. The impact of the façade ventilation area, window-to-wall ratio and thermal mass was more relevant in the scenarios where windows were always closed. The findings of this study can serve as a foundation for the development of strategies that promote occupant interaction with the façade which can lead to reduced building energy demand.
Conference paper
(2025)
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M.J. Tenpierik, Z. Huijbregts, T. Konstantinou, E. Brembilla, Alessandra Luna-Navarro, T.T. Jonathan, Spyros Bousios
Rising temperatures are leading to an increase in the cooling demand of buildings. Electrochromic (EC) glazing can be a promising solution for controlling solar heat gains while maintaining outdoor views. This paper presents the results of the monitoring of prototype panels of a novel type of inkjet-printed EC glass under real use and weather conditions in a small office building in the Netherlands. This building contained two identical west-facing meeting rooms of which one was equipped with EC triple glass IGUs and the other with normal triple glass IGUs. Each room was equipped with local heating/cooling units of which the energy use was monitored, and with an extensive environmental sensor network. Sensor and calendar data was fed into an energy balance model for each of the rooms for the entire measurement period, allowing to correct for differences between the two rooms with respect to heat losses and gains and use conditions. The results of the monitoring showed that in the meeting room with EC glass IGUs, the heating demand increased by 34% in Jan.-Mar. 2024 while in Sept. 2023 the cooling demand decreased by 3%. The main reason for the increase in heating demand was found to be the lower g-value of the EC glass IGUs in clear state as compared to the normal IGUs. The almost similar cooling demand was a result of a trade-off between the lower direct solar transmittance of the EC glass IGUs and the heating up of the absorptive layer inside the IGUs. Furthermore, an experiment with participants showed that in general in dark state, satisfaction with view clarity, daylight colour and daylight availability was higher for the EC glass IGUs. In transparent state, no significant difference was perceived between the EC glass IGUs and standard IGUs, except for view clarity.
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Rising temperatures are leading to an increase in the cooling demand of buildings. Electrochromic (EC) glazing can be a promising solution for controlling solar heat gains while maintaining outdoor views. This paper presents the results of the monitoring of prototype panels of a novel type of inkjet-printed EC glass under real use and weather conditions in a small office building in the Netherlands. This building contained two identical west-facing meeting rooms of which one was equipped with EC triple glass IGUs and the other with normal triple glass IGUs. Each room was equipped with local heating/cooling units of which the energy use was monitored, and with an extensive environmental sensor network. Sensor and calendar data was fed into an energy balance model for each of the rooms for the entire measurement period, allowing to correct for differences between the two rooms with respect to heat losses and gains and use conditions. The results of the monitoring showed that in the meeting room with EC glass IGUs, the heating demand increased by 34% in Jan.-Mar. 2024 while in Sept. 2023 the cooling demand decreased by 3%. The main reason for the increase in heating demand was found to be the lower g-value of the EC glass IGUs in clear state as compared to the normal IGUs. The almost similar cooling demand was a result of a trade-off between the lower direct solar transmittance of the EC glass IGUs and the heating up of the absorptive layer inside the IGUs. Furthermore, an experiment with participants showed that in general in dark state, satisfaction with view clarity, daylight colour and daylight availability was higher for the EC glass IGUs. In transparent state, no significant difference was perceived between the EC glass IGUs and standard IGUs, except for view clarity.