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Patterns of occupant interaction with window blinds: A literature review
Abstract
There is no comprehensive consensus about the way people operate blinds or the motivating factors that influence their decisions. However, there is a substantial body of research, encompassing data from more than 50 buildings worldwide, that offers guidance. Patterns of blind use can affect the energy consumption of buildings substantially and therefore energy and daylighting simulations that do not account properly for these blind use patterns will have greater error. An outline for a new more nuanced model for simulation-based blind control is offered. Specifically, this paper reviews the energy implications of blind use, blind occlusion and rate of change from field studies, specific quantitative measures influencing user blind control, investigations into user acceptance of automated blind control, and finally conclusions and knowledge gaps are summarized and suggested next steps for research are provided. Addressing these gaps is critical for the continued progress of the energy efficiency movement.
... People use window coverings, also known as blinds, for various reasons, and they can be installed inside, outdoors, or inside the walls of a building. Also, building energy consumption is impacted by the position and operation of blinds [12]. ...
... If placed outside of the thermal envelope, blinds have the potential to lower peak cooling demand and energy consumption. By reducing the amount of waste heat generated by lights, efficient daylight-sensing control systems can help lower cooling demands [12]. ...
... Improved predicted energy and natural lighting simulation accuracy requires an accurate understanding of blind use [12]. There are two blind-controlling systems: Manual user interaction and Automated blinds-by-control sensors. ...
... Windows provide daylight into buildings, visual connection to outside, and ventilation. To ensure that the indoor environment remains within comfortable limits, window shadings are often used when building users experience visual and/or thermal discomfort [1][2][3][4][5][6]. Climatic zone, geographical locations, and prevailing sky conditions will play seminal roles that determine blind occlusion patterns, preventing users from experiencing uncomfortable conditions (e.g., excessive sunlight) [7]. ...
... Climatic zone, geographical locations, and prevailing sky conditions will play seminal roles that determine blind occlusion patterns, preventing users from experiencing uncomfortable conditions (e.g., excessive sunlight) [7]. The orientation of windows relative to the Sun will also determine the likelihood of blind usage, depending on the time of day and year [3,6,8,9]. ...
... Predicting building users' control preferences and actions has become increasingly important to help understand building performance, energy demands, and to further develop extant building designs and systems [3,[10][11][12]. However, how user preferences and actions are determined by the indoor environment is not always well understood. ...
Window shading control is motivated by many reasons. Very few studies consider the influence of non-physical
factors that underpin occupant motives for shading control. A candidate reason that concerned this study was
cultural differences. Diverging values, beliefs and norms can lead to different design considerations for building
architecture to accommodate users’ expectations. This can also influence a wider array of window functions, e.g.,
daylight access, thermal comfort, natural ventilation, privacy and view out. We investigated the influence of
cultural differences in this context. An online survey was administered to collect responses from Arab and non-
Arab population groups from across the globe. We compared how occupants would prioritise different window
functions in their typical workspaces to better meet their needs across these two groups. The analyses showed
that Arab respondents prioritised privacy more than non-Arab respondents. The importance placed on privacy
was consistently larger for the Arab group when they worked from their own residential home (r = 0.36),
rather than at their office workspace (r = 0.16). Shading control for daylight access was a highly prioritised
motive for both groups, which was also equally weighted as the most important reason for both opening and
closing window shades with no statistical difference (r = -0.10) found between both groups. Thermal comfort
was deemed more important by the Arab respondents, although this may have been caused by climate factors.
The study highlights how culture has important implications on window preferences and shading control, which
can be influential in the context of design considerations to accommodate user needs.
... In the same way that From the previous paragraphs we know that dynamic, occupant-controlled shading objects are frequently deployed based on current standards and have significant impacts of light propagation in an interior. In reality they may be deployed more frequently (Van Den Wymelenberg 2012). Beyond what is typically assumed to be "building design," the selection of shading materials or types (such as venetian blinds or electrochromic windows) can have significant impacts on comfort and building performance. ...
... Jakubiec and Reinhart 2011;Heschong et al. 2012). Given that window shading systems are a part of a majority of architectural designs from commercial office buildings to residential buildings (Bennet, O'Brien, and Gunay 2014), it is sensible to include them in simulation results(Van Den Wymelenberg, Inanici, and Johnson 2010;Van Den Wymelenberg 2012;O'Brien, Kapsis, and Athienitis 2013;Konstantzos, Tzempelikos, and Chan 2015;Konstantzos and Tzempelikos 2017). ...
This chapter describes and visually illustrates three performance-driven design workflows that can be used to drive design decisions in very different contexts. First, spatial performance visualizations of passive architectural design in tropical climates are illustrated, constituting a passive design dashboard. Second, simple annual performance analysis of visual and thermal comfort is investigated for a range of façade options. Third and finally, the influence of dynamic elements such as window shades and temperature setpoints are considered relative to the conclusions of the previous simple analysis.
... However, simulating human behavior within buildings presents substantial challenges due to its inherently complex and unpredictable nature. Unlike mechanical systems, human actions are influenced by a myriad of factors, including personal preferences, cultural habits, and varying degrees of awareness about energy use [5][6][7]. This complexity poses difficulties in creating accurate and reliable simulations that reflect real-world scenarios. ...
Buildings significantly impact urban energy consumption. Mobile passive solutions, such asmanual solar protections, can mitigate heat gains, but their effectiveness depends on occupants’decisions. Analyzing occupant adjustments of manual systems is challenging due to thecomplexity of human behavior. While multiple studies have observed human-building in-teractions, analyzing large buildings over extended periods remains a technical challenge. Thisstudy examines 359 manually controlled solar protections over a year using systematic photo-graphic data. To manage the large volume of images, an unsupervised machine learning algo-rithm was employed to cluster similar solar protection positions for each window, which werethen manually tagged to identify their positions. Results show that solar protections are mostlyclosed year-round (28 % aperture on average), with minimal differences between occupied andnon-occupied days and between warm and cool seasons. Notably, one-third of the solar pro-tections were not operated throughout the year. Our results provide insights into the usage ofmanual façade systems and offer valuable knowledge for energy simulation. Methodologically,the use of machine-learning algorithms presents a new way to process large datasets of images,emphasizing the importance of prioritizing quality over quantity and strategic data collection.Future research can apply this methodology to different building types and climates to gainbroader insights into occupant behavior and solar protection interactions.
... Traditional blinds, one of the most common building skin types, primarily improve indoor daylighting performance by shading sunlight directly with a single performance objective. However, the design of blinds with a fixed tilt angle may lead to poor daylighting performance and potentially increase the energy consumption of the building [38]. Olbina et al. [39] pointed out that different parts of the window carry multiple functions, requiring different skin forms and control strategies in different parts of the window. ...
The adaptive façades serve as the interface between the indoor and outdoor energy of the building. Adaptive façade optimization design can improve daylighting performance, the thermal environment, view performance, and solar energy utilization efficiency, thus reducing building energy consumption. However, traditional design frameworks often neglect the influence of building envelope performance characteristics on adaptive façade optimization design. This paper aims to reveal the potential functional relationship between building façade performance characteristics and adaptive façade design. It proposes an adaptive façade optimization design framework based on building envelope performance characteristics. The method was then applied to a typical office building in northern China. This framework utilizes a K-means clustering algorithm to analyze building envelope performance characteristics, establish a link to adaptive façade design, and use the optimization algorithm and machine learning to make multi-objective optimization predictions. Finally, Pearson’s correlation analysis and visual decision tools were employed to explore the optimization potential of adaptive façades concerning indoor daylighting performance, view performance, and solar energy utilization. The results showed that the optimized adaptive façade design enhances useful daylight illuminance (UDI) by 0.52%, quality of view (QV) by 5.36%, and beneficial solar radiation energy (BSR) by 14.93% compared to traditional blinds. In addition, each office unit can generate 309.94 KWh of photovoltaic power per year using photovoltaic shading systems. The framework provides new perspectives and methods for adaptive façade optimization design, which helps to achieve multiple performance objectives for buildings.
... As an illustration, the LUR indicator can be affected by the occupants switching on the lights for hours of their presence [9]. In addition, glare levels from the penetration of direct sun light, being a significant factor, impact the operation of the blinds by the occupants [94], which affects KPIs like the useful daylight illuminance indicator or daylight glare probability (GDP) [95]. ...
... total solar heat transmittance of glazing g gl = 0.6 (X 3 = 0). After substituting X 2 , X 3 , and X 4 into Equation (15) and performing the appropriate calculations and algebraic simplifications, we have equations that provide a mathematical description of the recommended values of the window area with the physical parameters changed above for their north (19) and south (20) orientations, respectively. ...
Location is crucial when it comes to reducing the energy demand of buildings. Deterministic mathematical models of the energy demand of a single-family building were developed for the cities of Wrocław and Suwałki, representing the mild and severe climatic conditions of Poland, respectively, and compared with energy demand for Białystok, representing medium conditions. Models include the windows area, heat transfer coefficient, solar radiation transmittance of glazing, and orientation of windows. For medium conditions (Białystok), the energy demand is 18.3% higher than for mild conditions (Wrocław) and 7.3% lower than for severe climate conditions (Suwałki). Location does not influence the nature of the effect of the factors on energy demand, which increases with an increase in heat transfer coefficient and a decrease in window area, glazing solar radiation transmittance, and orientation change from north to south. The large impact of solar gains was proved. The optimisation procedure was performed and mathematical descriptions of recommended parameters were created to ensure the equivalent energy efficiency of windows for each orientation and location. For Bialystok, north-facing windows can have an area 1.32 times larger and south-facing windows 1.48 times smaller than east-facing windows to ensure a building’s energy demand remains constant.
... For example, occupants have been found to modulate window openings (e.g., using blinds) based on global horizontal radiation (e.g., Tokel, 2006) or radiation incident on windows (e.g., Inkarojrit , 2008) suggesting under periods of high radiation occupants may curtail their daylight access. If we examine types of users or occupants, daylighting studies have identified two types of users 1) active users 2) passive users ( Van Den Wymelenberg, 2012, Reinhart , 2004. Active users respond to environmental changes to modulate window openings and thus modulate the indoor environment. ...
The aim of this study is to assess the daylight access levels (vertical illuminance) in Indian homes. Daylight access levels in an occupied space on a given day are dependent on three main factors, the prevailing weather conditions, the design of the home, and occupant behavior. This study aims to isolate the effect of occupant interventions that result in lowering the daylight levels inside the home. The occupants may intervene intentionally or unconventionality in ways such as using curtains, hanging laundry, putting up screens, adding plants to balconies, furniture placement, and infrequent cleaning of windows. In this study, these are treated as occupant behavior traits that may impede daylight access. 12 homes in Ahmadabad (hot and dry climate) were monitored for a week each (data logged at 15-minute intervals, October 2022- Jan 2023) for daylight levels received in the living room. The use of electric lighting and activities being carried out by occupants were also monitored. The ideal potential of the home to provide daylight access, if no occupant interventions were present, is estimated using computer simulation. The frequency and duration of occupant interventions are estimated by running correlation tests between prevailing weather and indoor daylight levels.
... These include measures to reduce solar gain (e.g., shading), to remove internal heat (e.g., night ventilation), or to modulate the heat transfer profile (e.g., high thermal inertia) [21]. The two main passive measures of preventing overheating in summer: night ventilation and window shading are highly dependent on occupant behavior [22,23]. ...
Studies of the effects of removing underfloor insulation and increasing the thermal capacity of building walls are currently found almost exclusively in existing vernacular architecture and rammed-earth buildings, mostly in countries with warm climates. This paper proposes the combined use of these two measures to reduce the risk of overheating in a detached single-family house in a temperate climate during the summer. Experimental studies conducted during the largest heat wave on record in the summer of 2019 showed that peak daytime temperatures decreased by 5.2 °C to 7.1 °C, and peak nighttime temperatures decreased by 4.7 °C to 6.8 °C. Simulation studies taking into account occupant heat showed that the proposed passive methods could, under the IPCC 8.5 scenario, eliminate the need for mechanical cooling in a detached single-family house in the temperate climate of Central and Eastern Europe by 2100. The actual heating energy consumption for the building with an uninsulated floor and increased wall heat capacity was 5.5 kWh/m² higher than for the reference building, indicating that it can be a near-zero energy building. The proposed concept is in line with the new approach to the energy design of buildings, which should not be limited to reducing thermal energy demand, but should also respond to the needs arising from global warming.
... According to Clery et al. [45], while 25% of UK households use internal blinds in the summer heat, only 4% use the much more protective external blinds. Van den Wymelenberg [46] states that there is not enough knowledge about how people operate blinds and what motivates them. There is even less knowledge about this than about opening windows. ...
In most studies, the effect of the thermal capacity of the building envelope on changes in internal temperatures is reduced to a 24 h period. During this period, daytime heat gains are balanced by nighttime heat losses. The maximum indoor temperature, the diurnal variation of the indoor temperature and the time lag between the occurrence of the maximum daily temperature determine the effect achieved. The aim of the article was to show that the effect of the thermal capacity of a building on the indoor temperature is not limited to 24 h but accumulates over a period of several days, mainly depending on the temperature and solar radiation history of the previous days. As a result, contrary to what some studies have suggested, the bedrooms of heavier buildings remained significantly colder at night during periods of prolonged high outdoor temperatures. The results obtained may fundamentally influence the perception of the effect of using the high thermal capacity of the building envelope to reduce high indoor temperatures in hot weather.
... Despite the numerous benefits of access to daylight in indoor spaces, many existing workplaces do not actively use it [21], because daylight's dynamic nature makes it difficult to control; furthermore, it could cause glare or hinder thermal comfort [22,23]. To minimize these negative effects while providing daylight in indoor spaces, it is necessary to consider how it will enter the space during the building design stage. ...
The quality of indoor lighting significantly influences human well-being, emphasizing the need to integrate lighting planning into the architectural design process. To optimize indoor lighting conditions, light environment simulations are commonly employed. While much of the relevant literature clearly shows that simulations are widely used to predict lighting environments, there is limited active research validating these simulations. Therefore, this study aimed to assess the alignment between actual measurements and simulations, specifically focusing on daylight-induced glare. To achieve this, a comparative analysis and verification of glare levels between simulations and actual measurements were conducted that accounted for glare location and direction. Disparities between the simulated and measured glare levels were revealed contingent on the glare location and direction. These variations primarily arose from the simulation’s utilization of a fisheye field of view (FOV) for glare measurement. To improve the accuracy of glare analysis in simulations, it is advisable to follow the standards related to the human perception of glare, such as the human field of view (FOV), instead of solely depending on a fisheye FOV. The study’s limitations include challenges in environmental replication, minor measurement errors, and tree branch shading interference. Despite the potential for simulations to not replicate temporary glare effects, consistent differences with actual measurements indicate that the fisheye FOV was a key contributing factor.
... Among these, multiple studies highlight the importance of daylight mitigation, as the glare and visual comfort are strongly correlated [48,49]. Wymelenberg [50,51] claims to prioritize occupants' daylight and glare comfort over energy saving in fenestration control because it is reported that the level of indoor visual satisfaction, rather than the daylight level or thermal comfort, more critically motivate individuals to open/close win-dow shading. Therefore, in the design of automated KF control strategies, creating a glare-free environment should be prioritized over other factors [52]. ...
The authors present the first on-site investigation of artificial intelligence (AI)-integrated three-dimensionally movable kinetic façade (KF). Despite continued architectural interest on the KF to improve indoor visual comfort, its in-situ operational strategy has been little addressed. To examine our primary hypothesis that the adaptive KF controlled by AI models improves indoor daylight probability (DGP) in real time, we developed an electromagnetic hexagonal KF mechanism, and three machine-learning (ML) regressors (eXtreme Gradient Boosting (XGB), Random Forest (RFR), Decision Tree) were implemented on a Raspberry Pi board to control the KF (width = 1.73 m, height = 1.1 m). 20,000 data from Radiance were used for model construction, and illumi-nance sensors were installed for on-site validation in a private office mockup. The façade shape was optimally morphed every 90s, using differential evolution. In the verification, XGB showed the greatest accuracy (R 2 = 91.2%) with decent prediction time efficiency (μ = 0.58 s), but the RFR accuracy (R 2 = 79.8%) slightly outperformed XGB in the field.
... The blind position was estimated using a Python script based on the signal length of the blind movement. Shade adjustments frequency was reported as the number of movements per day per office [37]. In this study, UOAs are defined as the number of shade adjustments per each scenario. ...
This paper presents an experimental study conducted in a full-scale test cell ‘‘btga-box’’ from July until September 2020 at Wuppertal University, Germany. This study focused on evaluating occupant interaction and satisfaction with automated shading systems in office environments, and the underlying thermal and
visual conditions under different scenarios to optimize automated shading design and operation for improving occupant comfort and energy efficiency. Six different scenarios were evaluated using several performance metrics. Twenty-eight participants of varying ages, gender, and ethnicity took part in the experiments. After each scenario, the participants were asked to complete a web-based questionnaire to report their behaviour, their perceived thermal and visual comfort, satisfaction, and preferences concerning the performance of automated shading controls. Concurrently, indoor environmental parameters, weather data, and system and user-triggered actions were recorded. The key findings of this study suggest that a robust shading system (i.e., few override actions) can be achieved by: deploying a multi-objective control strategy with an intermediate
position, an acceptable range of irradiance thresholds, and a decent level of other adaptive behavioural control
options (i.e., window opening, fan usage, and light control). Providing active cooling or ventilation systems
(i.e., operable windows, exhaust ventilation, and ceiling fan) can improve user satisfaction with the indoor environment, including shade operation. Using a small window size combined with a high irradiance shade lowering threshold decreased the user-raising actions by 49% compared to the low threshold. However, energy
implications should be considered for further studies since user satisfaction with blind control should be balanced with energy efficiency.
... Still, it is crucial to avoid excessive sun penetration that could cause potential occupant discomfort [6]- [8]. When occupants experience visual discomfort from harsh sunlight, people usually shut the blinds, which can eventually increase electric energy consumption for room lighting [9]- [12]. The shut-off shading device setting would remain even after the discomfort issue was resolved, as most people were unlikely to adjust blinds actively over a day to maximize daylighting benefits [12], [13]. ...
p>The aim is to take full advantage of the natural sunlight inside the aircraft cabin. The paper presents the design of an intelligent window system for aircraft cabins, aiming to enhance the flight experience by automatically maintaining a personalised comfortable light level by changing the transparency of the electrochromic window. The system utilizes an adaptive Neural Fuzzy Inference System (ANFIS) to create personalized light levels, considering factors such as gender, age, activity, and Daylight Glare Index (DGI). The light level is controlled through a Proportional-Derivative (PD) based controller, which adjusts the transparency of the electrochromic window to achieve and maintain the desired lighting conditions. The automatic transparency control of the window and controller performance is realised in the test chamber. </p
... Still, it is crucial to avoid excessive sun penetration that could cause potential occupant discomfort [6]- [8]. When occupants experience visual discomfort from harsh sunlight, people usually shut the blinds, which can eventually increase electric energy consumption for room lighting [9]- [12]. The shut-off shading device setting would remain even after the discomfort issue was resolved, as most people were unlikely to adjust blinds actively over a day to maximize daylighting benefits [12], [13]. ...
p>The aim is to take full advantage of the natural sunlight inside the aircraft cabin. The paper presents the design of an intelligent window system for aircraft cabins, aiming to enhance the flight experience by automatically maintaining a personalised comfortable light level by changing the transparency of the electrochromic window. The system utilizes an adaptive Neural Fuzzy Inference System (ANFIS) to create personalized light levels, considering factors such as gender, age, activity, and Daylight Glare Index (DGI). The light level is controlled through a Proportional-Derivative (PD) based controller, which adjusts the transparency of the electrochromic window to achieve and maintain the desired lighting conditions. The automatic transparency control of the window and controller performance is realised in the test chamber. </p
... Manual shading controls lead to not well-lit spaces because of the lack of interaction between users and shading systems (Van Den Wymelenberg, 2012;Sadeghi et al., 2016). Hence, a well-designed static shading system can overcome this limitation, providing better performance on an annual basis. ...
Purpose
The paper aims to investigate the comfort-related performances of an innovative solar shading solution based on a new composite patented material that consists of a cement-based matrix coupled with a stretchable three-dimensional textile. The paper’s aim is, through a performance-based generative design approach, to develop a high-performance static shading system able to guarantee adequate daylit spaces, a connection with the outdoors and a glare-free environment in the view of a holistic and occupant-centric daylight assessment.
Design/methodology/approach
The paper describes the design and simulation process of a complex static shading system for digital manufacturing purposes. Initially, the optical material properties were characterized to calibrate radiance-based simulations. The developed models were then implemented in a multi-objective genetic optimization algorithm to improve the shading geometries, and their performance was assessed and compared with traditional external louvres and overhangs.
Findings
The system developed demonstrates, for a reference office space located in Milan (Italy), the potential of increasing useful daylight illuminance by 35% with a reduced glare of up to 70%–80% while providing better uniformity and connection with the outdoors as a result of a topological optimization of the shape and position of the openings.
Originality/value
The paper presents the innovative nature of a new composite material that, coupled with the proposed performance-based optimization process, enables the fabrication of optimized shading/cladding surfaces with complex geometries whose formability does not require ad hoc formworks, making the process fast and economic.
... The blind position was estimated using a Python script based on the signal length of the blind movement. Shade adjustments frequency was reported as the number of movements per day per office [37]. In this study, UOAs are defined as the number of shade adjustments per each scenario. ...
... Manually moveable shading devices are low in efficiency, depending on occupants' operation [31], and the estimation of their energy saving is unpredictable [31]. According to van den Wymelenberg (2012), digitally controlled motorized blinds benefit from monitoring blind positions through digital control points properly [36]. Manual operation of shading systems does not meet all the occupants' personal reference, visual, lighting, and thermal requirements. ...
In humid subtropical climates with a green environment, windows are the most dominant envelope elements affecting indoor visual and thermal comfort and visual connection to the outdoors. This research aims to optimize a dynamic external shading system for north-facing windows in Sydney, Australia, which acts automatically in eight predefined scenarios in response to indoor comfort conditions. The method of investigation was simulating a multi-objective optimization approach using Non-dominated Sorting Particle Swarm Optimization (NSPSO) to assess visual and thermal comfort along with energy usage and view of the outside. A combination of human and sensor assessments were applied to validate the simulations. A set of sensors and High Quality (HQ) cameras fed the system input to operate the shade. Simulations and field measurements demonstrated that optimized shading scenarios brought average yearly reductions of 71.43%, 72.52%, and 1.78% in Annual Solar Exposure, Spatial Daylight Glare, and LEED Quality View, respectively, without sacrificing Daylight Autonomy. Moreover, yearly improvements of 71.77% in cooling demand were achieved. The downside of the shading system was an increase of 0.80% in heating load and 23.76% in lighting electricity, which could be a trade-off for improved comfort and energy savings. This study investigated the effect of dynamic external shade on visual and thermal comfort together with energy usage and view, which has not been investigated for southern-hemisphere dwellings. A camera-sensor-fed mechanism operated the external shade automatically, providing indoor comfort without manual operation.
... Closed-loop controls consider indoor and outdoor feedback, while openloop controls do not. Studies on dynamic shading control show that in most countries, residential buildings use manual solar shadings, while office buildings, especially new office buildings, use automated control [28][29][30]. ...
Adaptive building envelope technologies can increase the energy efficiency of buildings. Adaptive facades can be controlled automatically and respond to environmental changes. There is no standard method for evaluating control strategies for adaptive façade elements, particularly for dynamic shadings. Therefore, the ISO/DIS 52016–3 recommended different default control strategies to compare the energy use of various building variants. ISO/DIS 52016–3 presents the procedures for considering the effect of adaptive building envelope elements in calculating the energy needs for heating, cooling, internal temperatures, and sensible and latent heat loads. This paper presents a comprehensive study of the impacts of the newly published ISO/DIS 52016–3 on energy performances and thermal comfort in office buildings with adaptive facades. The simulations were performed for an office room in Brussels with four scenarios: no shading and fixed shading (fixed horizontal louvers) with static control, external roller blinds, and Venetian blinds employing automatic control strategies suggested by ISO/DIS 52016–3. Energy Management Systems (EMS) as a user-customized coding plugin in EnergyPlus was utilised for implementation of each control strategy algorithm. The findings indicated that in the case of roller blinds, the energy performance of the selected office was improved by 19.47% compared to the fixed shading. This study shows that the chosen roller blinds performed the best in decreasing the annual cooling loads with a value of 63.9%, 44.12%, and 8.2% compared to scenarios of no shading, fixed shading, and Venetian blind, respectively. Furthermore, the results showed that the fixed shading would occasionally outperform automated Venetian blinds.
... In addition to higher levels of user satisfaction, occupants tend to utilize daylight more in offices with easy manual controls, leading to less lighting energy consumption [22]. The investigations regarding userbuilding interaction have revealed the pattern of user control on shade positions [23] and the energy implications of blind use [24]. The user-façade interaction is not affected only by the environmental conditions, as human attributes have been found to be a significant factor in predicting the shading and subsequently lighting controls [25]. ...
In shared office spaces, occupants' comfort criteria are limited to locally controlled zones while ambient features of the environment and the potential negative impacts of others' behavior require a well-designed control system, especially over adaptive façade elements. This means setting up control strategies for a wider spectrum of varying comfort perceptions from person to person dictates an approach towards personalizing adaptive facades. Thereby, this research coupled a simulation-based methodology with fuzzy logic and a genetic algorithm to personalize façade modules based on the visual discomfort conditions of the occupants. Results confirmed that increasing the control freedom by personalization accounting for multi-objective criteria including glare, daylight, and view could satisfy occupants from 83% to 100%. Moreover, the proposed façade personalization framework could enhance visual comfort compared with two typical automated Venetian blind controls, significantly. This study provides novel insights for designers and operators to decentralize facades' elements by accepting occupants’ feedback as part of their control loops.
... Another approach to building cooling is shading, which is influenced by equipment (e.g., Hussain et al. [26], Kim et al. [27]), user behaviour (e.g., Kevin [28], William et al. [29]), and control strategies (e.g., Line et al. [30], Amir et al. [31], Yun et al. [32]). ...
Passive houses have strong thermal insulation and airtightness of doors and windows, and they are generally used in cold climates. This case study aims to evaluate the energy-saving potential of this technology in the hot-summer and cold-winter areas (Cf in Köppen climate classification) of China. The results show that after enhancing the thermal insulation and airtightness, the energy consumption in winter significantly decreased by 62% overall. However, the energy consumption of cooling in the transition season and summer increased, which is caused by overheating. Hybrid ventilative cooling and shading can solve this problem. In particular, when the indoor temperature range is set to the adaptive thermal comfort of natural ventilation, the energy consumption from air conditioner cooling can be greatly reduced by 81% overall. Passive houses combined with ventilative cooling has significant application value in this climate zone.
... In the same way that From the previous paragraphs we know that dynamic, occupant-controlled shading objects are frequently deployed based on current standards and have significant impacts of light propagation in an interior. In reality they may be deployed more frequently (Van Den Wymelenberg 2012). Beyond what is typically assumed to be "building design," the selection of shading materials or types (such as venetian blinds or electrochromic windows) can have significant impacts on comfort and building performance. ...
... If adequately installed and managed, solar shadings allow to reduce both heating and cooling needs, maximizing solar gains in winter, and reducing loads in summer; indeed, coupled with proper building automation mechanisms, these systems may help achieving significant energy savings [5,10]. Moreover, the use of smart solar shadings can effectively influence occupants' comfort, in terms of both visual and thermal performance [10][11][12]. Solar shading devices can be manually operated by occupants according to their comfort perceptions or be automatically controlled through an efficient combination of sensors and actuators, which can enable the opening or closing of the different shading systems according to specific variables (e.g., internal temperature, external temperature, external solar radiation on window, etc.). In line with this, the use of smart automation and control strategies can increase their capability of optimizing the use of energy resources and building systems [5]. ...
In the framework of the current energy transition, the building sector is experiencing a smart revolution, recognizing how the adoption of advanced control strategies and smart management systems can increase buildings energy efficiency and improve occupants’ comfort. As a key element for smart buildings, solar shading devices coupled with effective control systems need to be strategically assessed. The investment decision-making process for selecting the proper shading systems is influenced by the existence of potential conflicts from economic, environmental, social, and energy standpoints, thus asking to be supported by innovative methodological approaches able to include all these aspects in the decisional framework. To this purpose, the work aims to propose a multi-disciplinary methodological framework to support decision-makers in ranking a set of solar shading device and relative control strategy, integrating energy dynamic simulations with multi-criteria decision analysis techniques. The analysis focuses on office buildings, recognizing their huge impact in terms of energy consumptions and the need to guarantee proper indoor conditions to increase employees’ productivity and well-being. To test the applicability of the multi-step methodology for this building category, the proposed approach is applied to an office building located in the North-West of Italy, aiming to assess and compare different alternative combinations of shadings devices and management strategies. The advanced features of building energy modelling and simulation and the application of PROMETHEE II (Preference Ranking Organization METHod for Enrichment Evaluation II) method as multi-criteria analysis allows to provide recommendations to decision-makers to identify the systems to be installed, able to guarantee the best trade-off between internal comfort, operational energy, and environmental costs for the building under investigation.
... Low sun angles are a feature of high latitude regions, where electric lighting is essential for both visual and thermal comfort and daylighting needs to be optimized [34,35]. A reasonable illuminance level able to contribute to an impression of daylight presence in building cores and rooms without vertical windows was found to be equal to 50 lux [36]. Office buildings use about 40% of their energy for electric lighting, but this rate becomes even higher for other building types, such as commercial or industrial [34]. ...
Transforming historical listed buildings into workplaces is a serious challenge, particularly for buildings with relatively small windows in the façades, which determine scarce daylighting indoors. This paper studied how daylighting can be significantly increased in a case-study historical building through rooflighting systems, as the façade cannot be modified. The case-study was a historic and iconic warehouse built-in 1681 in Trondheim, Norway. The optimized configuration was analyzed in terms of daylight amount and view analysis, according to EN 17037 and to LEED v4.1 protocol. A critical evaluation of the actual applicability of the optimized Scenario in the real building was carried out along with the constructors. A 3D model was built in Rhinoceros, and daylighting simulations of the base-case (the building in the existing configuration) and for 6 alternative Scenarios were run through Climate Studio. The following metrics were calculated: Daylight Factor (DF), Spatial Daylight Autonomy (sDA), Annual Sunlight Exposure (ASE), and views. An optimized configuration was eventually identified through the Galapagos component in Grasshopper, with an average DF value of 2.7% (against 0.9% in the base-case configuration), higher than the target DFm of 2.4% for Norway), and a sDA value of 50.2% (14.2% in base-case configuration).
... Literature has repeatedly, however, emphasized the influence of occupant daylight control on their satisfaction [29,43,44]. Van den Wymelenberg, for instance, reviewed the patterns of occupant interaction with window blinds [45], which was not solely focused on fabrics but also on venetian blinds. Among the identified research gaps, this paper listed the need to adequately address "blind occlusion" that shall reflect both "blind height and tilt" (in the case of venetian blinds) as both factors considerably affect view out, daylight provision, and glare. ...
Providing adequate glare protection and a view to the outside through fabric shading devices is challenging because these two objectives require conflicting material properties for a fully lowered shading. In a semi-controlled office-like experiment involving 32 participants, we investigated four types of neutrally-colored fabrics (charcoal and gray) with Openness Factors (OF) smaller than 7% focussing on view clarity, discomfort glare with the sun in the field of view, and participants' behavior when it comes to blind control. The results show that fabrics with OF<3% could provide adequate glare protection but no satisfactory view out. The charcoal-colored fabric of>6% resulted in lower glare protection but higher quality of view out. Our results show inconsistencies with the EN14501 blind classifications for glare and visual contact (i.e., view clarity), but good agreement with the recently developed view clarity index. During the final session, three quarters of participants raised the blinds to allow an average of 10° view to the outside, reporting as primary motivations the wish for more light and view out. Despite the relatively small rise of the fabric (15% of the total shade), daylight levels and view out were significantly improved, suggesting that operable blinds should not be controlled nor described according to the "all-or-nothing" approach. The change in fabric height did not compromise glare perception. These results suggest that if the control of shading height is effectively provided to occupants, then the fabric material could be selected primarily based on glare requirements.
Windows in buildings impact energy usage for temperature control through solar heat gain and enable natural light to reduce reliance on artificial lighting. Balancing solar heat gain and daylight utilization is a challenge, which can be addressed by employing automated or manual blind systems to manage daylight and enhance user comfort and energy efficiency. Additionally, accurate weather forecasts are essential for predicting energy-efficient strategies through individual building energy simulations, as weather conditions synergistically interact with occupant behavior to influence energy consumption patterns. This research aims to assess the energy consumption associated with manual and automated internal window blinds in medium-sized office buildings situated within two distinct and significant climate zones in the United States, considering both present and future climate change scenarios based on the IPCC report (RCP 4.5-8.5). Employing a simulation-based methodology, the study unveiled varying effectiveness levels of diverse window blind configurations contingent on the specific climate zones (e.g., 4A Mixed-Humid, 2B Hot-Dry). In different climate zones, on-site energy consumption alterations for heating and cooling become evident as temperatures escalate in the forthcoming years. Using simulation as the method and comparing RCP 4.5 and 8.5 scenarios reveals that automated blinds-a more efficient choice than manual blinds-significantly reduces cooling energy consumption, particularly under RCP 8.5 in a 4A Mixed-Humid zone. Rising temperatures in Climate Zone 2B Hot-Dry are a factor in increased energy requirements for cooling and decreased energy requirements for heating due to climate change. This study provides enlightening insights into the potential benefits of diverse window-covering strategies concerning energy conservation within varied climatic contexts for the future.
The emergence of adaptive facades offers a new approach for buildings to enhance their resilience against external weather conditions while responding to occupants’ demands, thereby improving both indoor environmental quality and energy performance. Appropriate control methods are crucial to achieving these purposes. However, most existing studies for automatic control of blinds have focused on visual comfort, leaving potential for further energy savings by reducing cooling and artificial lighting demands. Additionally, current optimization methods for slat angles are mostly simplified as a discrete process, neglecting the impact of thermal mass in building envelopes. Therefore, this paper aims to explore the energy reduction potential of window blinds by developing an iterative optimization method for devising hourly adaptive control strategies. To this end, a co-simulation platform between EnergyPlus and Python was established for the optimization and a case study in a subtropical city was conducted. The proposed strategies effectively balanced lighting and cooling demands to achieve an overall energy reduction of 7.3%–12.5% compared to reference cases while also ensuring visual comfort by mitigating glare risk and excessive daylight. These advantages were also compared with several simpler control scenarios, with analyses tailored to various glazing types and orientations. Furthermore, the optimal window configurations with blind control strategies for different orientations were determined. The findings also indicated that glass properties markedly impact the performance of control strategies, underscoring the necessity of holistically considering shading components and glazing types in the optimization to achieve optimal performance.
Computational performance-driven design optimization (CPDDO) informs early building design decisions, enhancing projects’ responsiveness to local climates. This paper reviews recent CPDDO studies, identifies prevalent gaps, and proposes a refined optimization framework. The framework stands out by: (1) integrating view quality alongside energy, daylight, and thermal comfort considerations, with a vector-simulation-based metric considering content, access and clarity; (2) incorporating users’ adaptive behavior patterns in simulations; and (3) employing a hybrid weighting method to accommodate diverse project demands and support robust design decisions. This study applies the framework to optimize the shape and facade variables of a medium-sized office building in Guangzhou, Chongqing, Qingdao, Lanzhou, and Changchun, representing hot, warm, mixed, cool, and cold climates, respectively. Results highlight that geometry features (aspect ratio, orientation, window-to-wall ratio (WWR), and shading devices), as well as window and blinds constructions significantly impact energy, daylight, thermal comfort and view quality. Different climatic conditions, objective priorities, and facade orientations necessitate tailored design variables. Furthermore, certain findings challenge conventional recommendations; for instance, buildings in colder climates benefit from increased WWR, due to enhanced potential to harness solar radiation and improved view access, while high-performance envelope thermal settings mitigate heat transfer. These findings underscore the need for detailed, targeted research in early-stage design. The developed CPDDO framework proves effective and user-friendly, offering new possibilities for optimizing building performance, thus holds the potential to foster green, comfortable, and sustainable architecture in various practical applications.
This study investigates the impact of varied daylight illuminance levels on user preferences and cognitive performance in offices, employing a virtual reality platform and HDRI 360-degree panorama images, whose illuminance level was validated using simulation. With 46 participants, a cognitive task known as the Stroop-test was conducted under nine illuminance levels, ranging up to 1500 lux. Additionally, participants were surveyed to determine their preferred horizontal illuminance level at desk height. The results uncovered distinct user preferences, with the majority of participants favoring illuminance levels above 700 lux, specifically 1100 and 790 lux, for reading and work-related tasks. Notably, none of the participants opted for illuminance levels below 300 lux, indicating these levels were deemed insufficient for their tasks. An analysis of cognitive task performance
revealed significant differences between various illuminance levels. Generally, increasing the illuminance level in an office building will increase the office workers’ task performance. As illuminance levels exceeded 300 lux, participants exhibited enhanced performance in tasks such as reading words (RW), naming colors (NC), and total Stroop-test performance (TT). The 700–1500 lux can be considered a suitable illuminance level for high precision tasks, and 300–700 lux can be considered the medium illuminance in office environments. Based on these findings, an optimal illuminance range of 900–1100 lux is recommended for office environments, aligning with both user preferences and performance. This study offers valuable insights for architects and researchers in the development of daylighting design guidelines aimed at enhancing employees’ cognitive capabilities and satisfaction.
Nowadays, thermal inner comfort has become a prerogative either for inhabitants, workers, or even casual users of any type of buildings. Simultaneously, current historic juncture has converted energy saving and CO2 emissions reduction into a must. Particularly, when it comes to patrimonial constructions in use, both objectives are to be achieved complying with the legal framework that ensures future preservation.
The aim of this work is to quantify eventual energy savings in an Asturian historical residence (the Busquets House), when comfort heating requirements are cut down. To do so, comfort condition has been established according to Dear and Brager (2001) adaptative model and reductions have been set according to lower 80% and 90% acceptable limits. A transient regime simulation of the house thermal behavior was also developed. Therein, former conditions were integrated as inputs and final heating energy demand was obtained as an output.
Simulation results revealed that, in a regular use scenario, 100% acceptability requires 12.317 MWh/year, 90% acceptability needs 8.183 MWh/year, and 80% acceptability demands 6.830 MWh/year. In other words, if criteria of 20% most cold-sensitive people were not to be considered, heating expenditure at the Busquets House could be reduced by 46.29%.
The world is facing a rapid increase of air conditioning of buildings. It is the motivation of Annex 80 to develop, assess and communicate solutions of resilient cooling and overheating protection. Resilient Cooling is used to denote low energy and low carbon cooling solutions that strengthen the ability of individuals and our community to withstand, and prevent, thermal and other impacts of changes in global and local climates. It encompasses the assessment and Research & Development of both active and passive cooling technologies of the following four groups: Reduce heat loads to people and indoor environments. Remove sensible heat from indoor environments. Enhance personal comfort apart from space cooling. Remove latent heat from indoor environments. The present review sums up the state of the art in cooling solutions which may be regarded as resilient. Its main objective is to systematically describe the available cooling solutions, their physical basis, their benefits and limitations, their technology readiness level, their practical availability, and applicability. Doing so, the State-of-the-Art Review forms the basis for the work of EBC Annex 80.
With the increasing demand for sustainable design and green
buildings, performance is becoming an important driving force
behind design decisions. Currently, however, possible solutions
explored to better building performance, considering the variety
of technological developments in other fields, are limited. Two of
the main limitations for an early designer are performance
evaluation methods and automation systems to facilitate
buildings to become smart. This research proposes a new shading
performance optimization and automation process that can help
designers evaluate both daylighting and energy performance,
generate optimized smart design options that can be optimized
during their service life to provide user-specific solutions to
occupants' needs.
The proposed method of performance optimization utilizes
various tools and technologies including parametric design,
building simulation modeling, Genetic Algorithms, and Machine
Learning tools. In this method, prevalent shading design
alternatives are explored through parametric design. Daylighting
and energy modeling simulations are performed to evaluate
shading device performance. Genetic Algorithms are used to
identify design options with optimal energy and daylighting
performance. And a user-specific automation algorithm is
developed to automate the performance of dynamic shading
devices. A case study is conducted to verify the effectiveness of
the overall design process. Various results were analyzed and the
potential influence of design decisions in different shading designs
was discussed. Finally, possible future work related to this
research is discussed.
Building ventilation rate is a crucial factor in the indoor air quality (IAQ). Furthermore, building-related parameters (window geometry, building orientation, height, and shape) have a substantial impact on the ventilation rates. However, most building designs reported in the literature from various income group countries failed to fulfill the recommended ventilation standards. A systematic and critical review was conducted on the collated literature from the past 20 years using various databases, yielding 145 related articles. Building-related factors influencing the ventilation rates were thoroughly studied in different income groups. In addition, the existing ventilation rates in various building environments were examined. The data analysis of critical literature suggests that the ventilation rates in 80% of the building environments were found lower than the prescribed standards irrespective of the income group countries. Thus, the current study highlights the need for redesign of the existing or new buildings for meeting the adequate ventilation rates.
Occupant behavior is one of the factors that impact the buildings’ energy consumption. Occupants interact with building systems to adjust their indoor environmental conditions to meet their comfort levels. Occupants’ behavior to control those multiple conditions have been studied in isolation. Previous research highlighted the impact that contextual factors, such as interior design, have on occupants’ energy-related behaviors. This study focused on psychological, contextual, and environmental reasons leading to energy-related occupants’ behavior. It investigated the impact of spatial factors: orientation, floor level, space type, and furniture layout on occupants’ behavioral beliefs about operating windows and adjusting blinds. Results revealed a significant relationship between the spatial factors and occupants’ behavioral beliefs about operating windows and adjusting blinds. It is recommended to consider occupants’ behavioral beliefs related to the spatial factors in the preliminary stages of the design process to contribute to efficient space planning and thus enhance the building’s energy performance.
Roller blinds can reduce the heating and cooling building energy consumption required to maintain thermal comfort. The effectiveness of roller blinds is influenced by the strategies and input parameters for their control. This study is the first to identify the most effective of seven alternative control parameters to control roller blinds. It further defines the benefits from using paired control parameters to maximise energy savings and optimise occupants' comfort. For the particular case studies and conditions examined, it is concluded that operating roller blinds using indoor air temperature as a single control parameter with rule-based controller provided, 16 %, 19 % and 45 % in heating, cooling and lighting energy savings in Dublin, Berlin and Madrid respectively compared to a window without roller blinds, with an average 51 % daylight discomfort reduction. Using both internal temperature and outdoor ambient temperature to control the roller blinds had little effect on energy need, with only a further 0.6 %, 0.5 % and 0.3 % energy savings and an average of 2 % reduction in daylight discomfort achieved compared to using solely indoor temperature as the control parameter.
The sustainability of vernacular dwellings is closely connected with the fulfilment of the daily needs of the inhabitants, as well as the incorporation of multiple environmental features into their design. These environmental features ensure a climate responsive approach and improve the thermal performance of the dwellings. The vernacular architecture of Cyprus follows the main principles of vernacular architecture in the eastern Mediterranean region as a whole, and thus it is considered as a typical case study, suitable for in-depth investigation. The research findings presented here are an overview of systematic research carried out over the last ten years at the University of Cyprus, mainly through two multidisciplinary research programmes. Specifically, various environmental aspects were thoroughly investigated, starting from the selection and investigation of rural and urban settlements in different climatic areas (urban scale), moving to the building scale and to the selection of a representative number of vernacular dwellings for qualitative, as well as quantitative investigation. Following this, the research focuses on the different spaces within the dwellings (such as courtyards, semi-open spaces and subterranean areas), as well as on various passive strategies (such as ventilation and lighting), ending with the investigation of the thermal behaviour of the traditional building materials used for the erection of the aforementioned dwellings. The research reveals the necessity for a qualitative and quantitative assessment of vernacular architecture through a multicriteria process, and indicates a methodology that can be implemented in other similar cases especially around the Mediterranean area.
In this text, the history of thermal comfort metrics (Chap. 2) and visual comfort metrics (Chap. 3) has been traced, forming the basis of an understanding for how the practice of building performance and occupant comfort has arrived at contemporary comfort measures. This was followed by illustrative examples of simulation-based workflows integrating comfort in theoretical design projects (Chap. 4), primarily with a focus on decision-making and visual communication. This terminal chapter provides the author’s opinionated point of view on the current state of practice and where it may head in the future.
The history of human understanding of visual discomfort and the derivation of metrics to assess discomfort glare are chronicled. The time covered by this discussion is from the early 1900s until the present day. By understanding how assessment of visual discomfort has developed over time, the reader will gain an understanding of the challenges of discomfort glare analysis today.
The history of the understanding of thermal comfort and its translation into thermal comfort standards are described within this chapter. The focus of this study is largely historical, beginning with early designs of heating and air conditioning and concluding with the recent versions of ASHRAE 55 and ISO 7730. Through tracing the history of thermal comfort in this way, an understanding can be gained of our current assessment practices for thermal discomfort. The chapter concludes with contemporary research-driven criticism of current thermal comfort standards.
This study aims to categorise the existing irradiance-based blind control occupant behaviour models (BC-OBMs) into distinct clusters of the same characteristics using an unsupervised machine learning approach. Fourteen BC-OBMs, including two base case models (blinds always opened – AL1 and always closed – AL2), have been simulated for an office building in Tiruchirappalli, India and categorised into three distinct clusters named: Passive open (C1), Passive close (C2), and Active (C3). C1 and C2 performed similarly to the base case models, AL1 and AL2, respectively. In contrast, C3 performed as an active cluster with a high number of blind movements (NBMs). This study also quantifies the degree of absolute error between the identified clusters and the base case model AL1 (as per the practice followed in Indian building energy codes) and emphasises the need to incorporate the BC-OBMs into the building energy codes to predict the artificial lighting consumption and lighting levels accurately. To the best of the authors' knowledge, this study is a novel attempt to categorise the existing irradiance-based BC-OBMs into distinct clusters. The research methodology adopted for this study can also be used in future research to categorise the window, artificial light, fan, and thermostat use OBMs into distinctive categories.
One of the most important concerns when designing buildings as liveable spaces is the indoor comfort. This depends on different factors, including daylight availability and discomfort glare conditions.
The increasing use of glazing areas in the building's envelopes can lead to high energy consumption and problems such as visual discomfort. The use of shading devices stands out as a sustainable design strategy to reduce energy consumption in the buildings. This work presents an experimental analysis of the impact of an innovative shading device, a double-tilted venetian blind (DTVB) with different positions of upper and lower slats, on the indoor daylight conditions. Moreover, discomfort glare evaluation, through DGPs metric, is performed.
The experimental campaign was conducted in an outdoor test cell during three periods of the year: summer solstice, winter solstice and autumn equinox. Experiments were carried out with both white and grey DTVBs, for several positions of upper and lower slats, under clear and overcast sky conditions. This comprises the measurement of indoor and outdoor horizontal and vertical illuminances and irradiances and solar and visible transmittance of the fenestration. It was concluded that DTVBs can achieve a higher performance, regarding solar protection, daylighting and glare control, when compared with more traditional venetian blinds systems.
A post occupancy field study of daylit classrooms in three new elementary schools identifies perceptual and behavioural dimensions that impact the success of sidelighting strategies. The research utilizes multiple methods including observation, measurement, and teacher surveys to uncover a balance of quantitative and qualitative attributes. The emergent theme is that despite apparent issues associated with daylight variability and control, teachers are enthusiastic about the asset of natural light and views. Better interior management of the daylight source has the potential to improve the quality of the luminous environment and increase energy savings. Daylighting strategies should be considered within the context of orientation and end-user interactions.
In this paper, the potential, limitations and applicability of the High Dynamic Range (HDR) photography technique are evaluated as a luminance mapping tool. Multiple exposure photographs of static scenes were taken with a commercially available digital camera to capture the wide luminance variation within the scenes. The camera response function was computationally derived by using Photosphere software, and was used to fuse the multiple photographs into an HDR image. The vignetting effects and point spread function of the camera and lens system were determined. Laboratory and field studies showed that the pixel values in the HDR photographs correspond to the physical quantity of luminance with reasonable precision and repeatability.
We describe two methods which rely on bidirectional scattering distribution functions (BSDFs) to model the daylighting performance of complex fenestration systems (CFS), enabling greater flexibility and accuracy in evaluating arbitrary assemblies of glazing, shading, and other optically-complex coplanar window systems. Two tools within Radiance enable a) efficient annual performance evaluations of CFS, and b) accurate renderings of CFS despite the loss of spatial resolution associated with low-resolution BSDF datasets for inhomogeneous systems. Validation, accuracy, and limitations of the methods are discussed.
Solar shading devices are commonly used in offices to reduce cooling loads and glare from windows, but they also affect daylighting and the view to the outside. In this study, the function and op-eration of an awning and an exterior venetian blind as well as their influence on the view out was assessed by fifty office workers. The preferred position of the shading devices, the interior illumination and the weather conditions were recorded. An interior dimmable lighting fixture was introduced in order to see if there was a difference between the shading devices regarding the need of complementary electric lighting. The awning was found easier to adjust than the venetian blind. Both shading devices somewhat affected the view to the outside. The shading devices were used frequently to avoid glare from the window. How-ever, preliminary results show no or weak correlation between common lighting concepts such as interior illuminance or sky luminance and how much the shading device was pulled down. On the other hand, there was a weak relationship between the existence of sunlight patches in the room and the position of the shading device. Further, the awning showed to be sensitive to wind, creating a disturbing "flickering" sunlight patch on sunny, windy days. There was no difference between the shading systems in the use of complementary electric lighting.
A simulation algorithm is proposed that predicts the lighting energy performance of manually and automatically controlled electric lighting and blind systems in private and two-person offices. Algorithm inputs are annual profiles of user occupancy and work plane illuminances. These two inputs are combined with probabilistic switching patterns, which have been derived from field data, in order to predict the status of the electric lighting and blinds throughout the year. The model features four different user types to mimic variation in control behavior between different occupants.An example application in a private office with a southern facade yields that––depending on the user type––the electric lighting energy demand for a manually controlled electric lighting and blind system ranges from 10 to 39 kW h/m2 yr. The predicted mean energy savings of a switch-off occupancy sensor in the example office are 20%. Depending on how reliably occupants switch off a dimmed lighting system, mean electric lighting energy savings due to a daylight-linked photocell control range from 60% to zero.
We registered how eight subjects used their remotely controlled black Venetian blinds in eight individual offices, every 15 min, over a period of 30 weeks. This also included measuring parameters such as the illuminance on the window, the illuminance on the VDU screen, the ambient temperature inside the room, the presence of the worker and the state of the artificial lighting. During the same period, we registered the position of the blinds in seven other offices fitted with manually controlled fabric blinds, through webcam pictures taken every 15 min. There was no further monitoring inside these offices.With the data collected, several hypotheses regarding the use of Venetian blinds in offices were tested. It appeared that office workers were consistent in the way they used their shading system, however it was difficult to draw general conclusions on blind usage. The type of control of the shading system also seemed to be important. Remotely controlled black Venetian blinds were used three times more often than manually controlled fabric blinds. In addition, most of the time users adjusted the tilt of the slats of the Venetian blinds downwards, towards the external ground. We also came to the conclusion that the higher the quality of the VDU screen (in terms of emitted luminance levels), the more likely a worker was to tolerate high levels of diffuse reflections on it, hence taking more advantage of the daylight available.
This paper reviews, validates and extends present knowledge of the degree and kind of manual control strategies of blinds and electric lighting systems that are used in private and two-person offices. A new monitoring setup was applied from March to December 2000 in 10 daylit offices in Germany that featured manually operated electric lighting and automatically controlled external venetian blinds with manual override. The data shows that individuals consistently followed the same control strategy for their electric lighting and blinds. Groups of individuals tended to activate their electric lighting according to Hunt's probability function, although there was a large spread between individual control levels. All subjects used their blinds to avoid direct sunlight above 50 W/m2, and incoming solar gains above 50 klux (∼450 W/m2). They also were more willing to accept automatic blind opening than closing.
Estimations of daylight factors, used to calculate energy savings, typically do not consider occupants' use of window blinds. The data indicate that such estimations should include some assessment of window blind usage, because over half of the window area is usually occluded in some way by blinds. It appears that many occupants purposely use window blinds to sunlight from penetrating their working space. Rsum Dans l'estimation des coefficients d'clairage de jour, qui servent calculer les conomies d'nergie, on ne tient gnralement pas compte de l'utilisation des stores par les occupants. Les rsultats de travaux indiquent qu'il faudrait le faire, car plus de la moiti de la superficie des fentres est habituellement occluse, d'une faon ou d'une autre, par des stores. Il semble que nombre d'occupants s'en servent pour empcher la lumire solaire de pntrer dans leur lieu de travail.
The control strategies for coordinating the variable solar-optical properties of a dynamic building envelope system with a daylight-controlled electric lighting system have been studied with the aim of reducing electricity consumption and increase comfort in the perimeter zone of commercial buildings. Using the DOE-2 building energy simulation program, it is shown that (1) predictive control algorithms may significantly increase the energy efficiency of systems with nonoptimal solar-optical properties, such automated venetian blinds, and (2) simpler, nonpredictive control strategies may suffice for more advanced envelope systems incorporating spectrally selective, narrow-band electrochromic coatings.
Daylight has the potential to positively impact occupants and reduce energy consumption in buildings if utilized correctly (Edwards & Torcellini, 2002). However, unintended negative outcomes can arise from unsuccessful daylighting schemes. Common issues, such as glare and heat gain, are important architectural considerations in design of the building envelope, but less studied are corresponding interior design considerations (such as furniture layout and access to controls) and associated occupant interactions and appraisals. The purpose of the current study is to expose some of the key issues related to the occupant use of daylight and daylight control in perimeter offices, to discuss the contributing design process factors, and to suggest possible improvements to the design process including an increased role for interior designers. The research methodology followed a case study approach and included post-occupancy evaluation (POE) questionnaires, interviews, and observations of a single higher education building with intentionally daylit perimeter offices. We discovered that the building in question was passed between three separate design teams throughout the design process, which may have contributed to the lack of integration between the architectural daylight design and the interior furniture and daylighting control fit-out. More than 50% of total respondents (n = 35) reported obstructed blind controls due to poor furniture design and layout. Of these, nearly 60% of occupants modified their office environment to gain access to blind controls. Ultimately, findings of this study demonstrate the importance of an integrated, multidisciplinary approach to daylighting design, one that considers both the specific building context and the human response.
Dynamic envelope/lighting systems have the potential to optimize the perimeter zone energy balance between daylight admission and solar heat gain rejection on a real-time basis, and to increase occupant comfort. Two side-by-side full-scale offices in Oakland, California were built to further develop and test this concept. An automated venetian blind was operated in synchronization with a dimmable electric lighting system to block direct sun, provide the design workplane illuminance, and maximize view. The research program encompassed system design refinements, energy measurements, and human factors tests. In this study, we present lighting energy and cooling load data that were monitored in this facility over the course of a year. Significant energy savings and peak demand reductions were attained with the automated Venetian blind/lighting system compared to a static venetian blind with the same dimmable electric lighting system. Correlations between key weather parameters and cooling and lighting were used to illustrate how the dynamic system was able to simultaneously achieve optimization between lighting and cooling end uses under the full range of weather conditions of this sunny, moderate climate. Energy efficiency estimates were conservative since experience shows that conventional daylighting control systems and manually operated shading devices are rarely used effectively in real world applications.
New research in daylighting metrics and developments in validated digital High Dynamic Range (HDR) photography techniques suggest that luminance based lighting controls have the potential to provide occupant satisfaction and energy saving improvements over traditional illuminance based lighting controls. This paper studies occupant preference and acceptance of patterns of luminance using HDR imaging and a repeated measures design methodology in a daylit office environment. Three existing luminance threshold analysis methods [method1: predetermined absolute luminance threshold (for example, 2000 cd/m2), method2: scene based mean luminance threshold and method3: task based mean luminance threshold] were studied along with additional candidate metrics for their ability to explain luminance variability of 18 participant assessments of ‘preferred’ and just disturbing' scenes under daylighting conditions. Per-pixel luminance data from each scene were used to calculate Daylighting Glare Probability (DGP), Daylight Glare Index (DGI), and other candidate metrics using these three luminance threshold analysis methods. Of the established methods, the most consistent and effective metrics to explain variability in subjective responses were found to be; mean luminance of the task (using method3; adjr2 = 0.59), mean luminance of the entire scene (using method2; adjr2 = 0.44), and DGP using 2000 cd/m2 as a glare source identifier (using method1; adjr2 = 0.41). Of the 150 candidate metrics tested, the most effective was the ‘mean luminance of the glare sources’, where the glare sources were identified as 7* the mean luminance of the task position (adjr2 = 0.64). Furthermore, DGP consistently performed better than DGI, confirming previous findings. ‘Preferred’ scenes never had more than 10 percent of the field of view (FOV) that exceeded 2000 cd/m2. Standard deviation of the entire scene luminance also proved to be a good predictor of satisfaction with general visual appearance.
The control actions by the inhabitants of buildings can significantly affect the energy performance of buildings and their environmental impact. However, relatively few studies have investigated such actions in detail and on a long-term basis. In most buildings, occupants operate control devices such as windows, shades, luminaries, radiators, and fans to bring about desirable indoor environmental conditions. Knowledge of such user actions is crucial for accurate prediction of building performance (energy use, indoor climate) and effective operation of building service systems. The present contribution describes an effort to observe control-oriented occupant behavior in office buildings in Austria over a period of 1 year. Thereby, user control actions as related to one or more of the building systems for ambient lighting, shading, window ventilation, and heating were monitored together with indoor and outdoor environmental parameters. The collected data has been analyzed to explore relationships between the kinds and frequency of the control actions and the magnitude and dynamism of indoor and outdoor environmental changes. Moreover, implications of user actions for energy use are studied.
Luminous environment apects related to the integration of control systems with ElectroChromic (EC) windows for non-residential buildings are analyzed. On/off and linear control strategies to reverse the EC transparency from the bleached to the coloured state, integrated with dimming and on/off artificial light control systems, are investigated as regards visual aspects. Different EC window systems are compared with a double sheet glass system equipped with different internal shading for some Italian cities in typical Mediterranean geographic areas. An integrated energy analysis program, IENUS (Integrated Energy Use Simulation), that simulates hourly thermal and luminous aspects on the base of TMYs (Typical Meteorological Years) is used as a work tool.
Commercial buildings with large exposed glazed façades require solar shading devices in order to protect occupants from uncomfortable direct glare. Automated window blinds can be used to reduce direct glare, while regulating the transmittance of daylight or solar gains. At the same time, they may be integrated with the building automation system to provide load management by limiting solar gains and by adjusting electric lighting levels based on the available daylight. The purpose of this study is to model the light transmittance of a window-venetian blind system, and to simulate and measure the controlled system performance regarding daylighting efficiency, and the reduction in electric lighting power consumption. Blind control is to be carried out only when exterior solar radiation levels exceed a certain threshold; otherwise the blinds remain fully open (horizontal) in order to maximize view and daylight provision. In order to verify the model results, measurements are being taken at the Concordia University Solar Laboratory. This paper presents the measured transmitted illuminance measurements with the controlled venetian blind, as well as the associated lighting energy savings.
An innovative automated blind and lighting control system was developed to eliminate direct solar penetration and keep working plane illuminances within an optimal range, while making maximum use of daylight, and minimizing blind movement. Data collected from a controlled experiment indicate that the system eliminated direct solar glare and kept the working plane illuminance within the target range, while providing only 30% more electric lighting than a theoretical system with no blinds and perfect knowledge of the working plane illuminance. The system needed to provide 60% less electric lighting than a similar system with switchable rather than dimmable luminaires. Total blind movement varied from less than 1 min to over 6 min in one day depending on the weather, with an average of 190 s. Similar integrated systems have the potential to save a large fraction of the electricity used for lighting, while providing an amenable visual environment.
This study investigates control strategies for coordinating the variable solar-optical properties of a dynamic building envelope system with a daylight controlled electric lighting system to reduce electricity consumption and increase comfort in the perimeter zone of commercial buildings. Control strategy design can be based on either simple, instantaneous measured data, or on complex, predictive algorithms that estimate the energy consumption for a selected operating state of the dynamic envelope and lighting system. The potential benefits of optimizing the operation of a dynamic envelope and lighting system are (1) significant reductions in electrical energy end-uses - lighting, and cooling due to solar and lighting heat gains - over that achieved by conventional static envelope and lighting systems, (2) significant reductions in peak demand, and (3) increased occupant visual and thermal comfort. The DOE-2 building energy simulation program was used to model two dynamic envelope and lighting systems, an automated venetian blind and an electrochromic glazing system, and their control strategies under a range of building conditions. The energy performance of simple control strategies are compared to the optimum performance of a theoretical envelope and lighting system to determine the maximum potential benefit of using more complex, predictive control algorithms. Results indicate that (1) predictive control algorithms may significantly increase the energy-efficiency of systems with non-optimal solar-optical properties such as the automated venetian blind, and (2) simpler, non-predictive control strategies may suffice for more advanced envelope systems 1 incorporating spectrally selective, narrow-band electrochromic coatings.
Blinds are used widely in numerous buildings to conserve energy and provide for occupants' comfort in the perimeter zone. However, manual or motorized blinds are limited in their ability to reduce energy consumption and to provide comfort because occupants themselves must operate blinds to block direct solar radiation. Thus, the use of automated blinds would more fully exploit the full benefits of blinds.This study aims to find out whether the environmental performance of a building can be improved by the application of an automated Venetian blind in comparison to a manual or motorized Venetian blind and whether occupants may feel discomfort by the application of an automated Venetian blind in the summer season. This study also aims to find out the insufficiency of the automatic control algorithm of that automated Venetian blind for future study of the development of that algorithm.Through this study, the potential energy savings and the comfort enhancement when using the automated blind was confirmed and the insufficiency of the automatic control algorithm of that was also found out.
Adequate indoor illuminance is accepted as one important determinant of conditions for comfort and productivity in offices. This paper uses the results of field surveys in 26 offices in five European countries (France, Greece, Portugal, Sweden and the UK) to investigate what illuminance levels are actually achieved on office desks, what light level is considered ‘best’ by occupants, and how this is affected by outdoor sky conditions and illuminance. The paper also explores how blinds and lights are used by occupants to modify light levels at their desks. The office workers show a remarkable degree of adaptation to different light intensities. They use controls to modify the light level at their desks to almost the same mean level irrespective of the sky conditions outside. There is a small but significant effect of lighting on self-reported productivity which seems to be higher when offices are daylit.
The energy efficiency of switchable (variable transmittance) windows having a control system based on occupancy, temperature and impinging solar radiation is evaluated. The heating and cooling performance of the switchable windows are compared with the performance of several conventional glazings. The study indicates that the energy efficiency of switchable windows depends highly on several different parameters, such as location, type of building, orientation, occupancy, etc., but that there is a potential to use a "intelligent" control system for the switchable window in order to reduce the need for external energy and potentially also improve the comfort. The energy efficiency of switchable windows increases with internal heat production and is more beneficial the sunnier and the warmer the location is.
Industries have developed different types of transparent materials and light control systems to improve the design and the operation of buildings to take full advantage of daylight. This paper analyses energy, thermal and visual aspects connected to the integration of electrochromic windows as a part of a light control system. Energy saving and environmental control optimizations for non-residential buildings are analyzed by the advanced simulation package Integrated ENergy Use Simulation (IENUS), that can integrate thermal and visual aspects. Different double-glazed electrochromic windows and light management strategies are taken up for Mediterranean climate using Typical Meteorological Years (TMY).
A prototype integrated, dynamic building envelope and lighting system designed to optimize daylight admission and solar heat gain rejection on a real-time basis in a commercial office building is evaluated. Office worker response to the system and occupant-based modifications to the control system are investigated to determine if the design and operation of the prototype system can be improved. Key findings from the study are: (1) the prototype integrated envelope and lighting system is ready for field testing, (2) most office workers (N= 14) were satisfied with the system, and (3) there were few complaints. Additional studies are needed to explain how illuminance distribution, lighting quality, and room design can affect workplane illuminance preferences.
Estimations of daylight factors, used to calculate energy savings, typically do not consider occupants' use of window blinds. The data indicate that such estimations should include some assessment of window blind usage, because over half of the window area is usually occluded in some way by blinds. It appears that many occupants purposely use window blinds to prevent sunlight from penetrating their working space.
Based on almost seven years of continuous measurements, we have analysed in detail the influence of occupancy patterns, indoor temperature and outdoor climate parameters (temperature, wind speed and direction, relative humidity and rainfall) on window opening and closing behaviour. In this we have also considered the variability of behaviours between individuals. This paper begins by presenting some of the key findings from these analyses. We go on to develop and test several modelling approaches, including logistic probability distributions, Markov chains and continuous-time random processes. Based on detailed statistical analysis and cross-validation of each variant, we propose a hybrid of these techniques which models stochastic usage behaviour in a comprehensive and efficient way. We conclude by describing an algorithm for implementing this model in dynamic building simulation tools.
Algorithms to describe the manual control of window blinds and electric lighting, in response to comfort stimuli, were incorporated into a building thermal model. By comparison with fixed control schedules, this paper examines the impact of manual control on model predictions of thermal comfort and building energy consumption. For a typical, south-facing office in Toronto, the thermal comfort of an occupant close to the window was substantially improved by the provision of window blinds. Compared to an office with no blinds, mean PPD (predicted percentage of occupants dissatisfied with the thermal environment) was lowered from 22 to 13%, and overheated hours were reduced by over 200 per year. However, when the lighting was also manually controlled, the blinds imposed an energy penalty. Though reduced solar gain lowered cooling energy by 7%, heating energy increased by 17%, and reduced daylight increased lighting energy by 66%. The implications of these results on the modelling of occupied buildings are discussed. Des algorithmes servant à décrire la commande manuelle des stores et de l'éclairage électrique, en réponse à des stimulus relatifs au confort, ont été incorporés dans un modèle thermique de bâtiment. En procédant par comparaison avec des programmes de commande fixes, on examine dans le document l'incidence de la commande manuelle sur des prédictions de modèle de confort thermique et de consommation d'énergie du bâtiment. Dans le cas d'un bureau type orienté vers le sud à Toronto, la pose de stores a amélioré de façon substantielle le confort thermique d'un occupant se trouvant à proximité de la fenêtre. Par comparaison avec un bureau dont les fenêtres n'étaient munies d'aucun store, le PPD moyen (pourcentage prévisible d'insatisfaits de l'environnement thermique) a diminué de 22 à 13 % et les heures de surchauffe ont été réduites de plus de 200 par année. Cependant, lorsque l'éclairage était lui aussi commandé manuellement, la présence de stores entraînait une perte énergétique. Même si la réduction des gains d'énergie solaire a fait diminuer de 7 % la consommation d'énergie de refroidissement, la consommation d'énergie de chauffage a augmenté de 17 % et la réduction de la lumière naturelle a entraîné une augmentation de 66 % de la consommation d'énergie liée à l'éclairage. Le document traite des répercussions de ces résultats sur la modélisation des bâtiments occupés. RES
The central goal of this project within the SAVE programme is to obtain a reliable estimate of how the use of daylighting technologies could contribute to a reduction of total energy use in buildings, changes in the profile of peak electric loads and environmental effects. The use of daylighting controls coupled with energy efficient lighting and novel daylighting technologies shows potential in reducing electricity consumption in buildings and providing better thermal and visual comfort for the occupants. In the long term cost benefits are projected due to lower energy bills and in some cases potentially lower capital costs due to the smaller installed capacity required for the heating and cooling system.
Thesis (Ph. D. in Architecture)--University of California, Berkeley, Fall 2005. Includes bibliographical references (leaves 222-237).
Examines the current assumptions in occupants' use of blinds and the impact these assumptions have on a building's environment. It then compares the assumed use with the actual use from monitored data of blind use in both summer and winter conditions in 3 buildings. In particular, the impact of facade orientation, sunshine, and electric lighting on blind use is investigated. Results confirm that on average, 40% of a building's facade is obscured by blinds resulting in a reduction in daylight. This reduction in daylight is equivalent to an unobstructed glazed area of 68% of the building's facade. Occupants' use of blinds is predominantly not affected by solar availability as often modelled.
This thesis describes the results of a research to find out how users interact with shading and lighting devices in an office building in Vienna, Austria. The aim of the research is to explore the parameters that lead occupants to change shade positions. For this purpose, changes in shading on the southwest and north fa?ades of the building were observed by capturing images of the whole fa?ade. Weather conditions were registered by the weather station mounted on the top of the building. Inside the building, 15 rooms on the southwest fa?ade and 14 rooms on the north fa?ade were selected. Users? operation of lighting was captured in each room. Data over a period of twelve months was collected and analyzed. The relationship between users? behavior and environmental parameters was studied. The potential for energy saving through the use of occupancy sensors was explored.
Reliable simulation of buildings' energy performance requires, amongst other things, the availability of detailed information on the magnitudes of incident solar radiation on building facades. However, the availability of the measured data concerning the incident solar radiation on vertical surfaces is restricted to only few locations. In addition, concurrent measurements of horizontal global and horizontal diffuse (or direct normal) irradiance data are likewise available only for a limited number of locations. In contrast, global horizontal irradiance data is available for many locations. This research demonstrates how to computationally derive incident irradiance values on vertical (or otherwise inclined) building surfaces from measured globalirradiance values. Given this context, three methods are considered to compute incident vertical irradiance values based on measured global horizontal irradiance data. Vertical solar irradiance measurements are described. Then, the computationally derived values are compared withcorresponding measurements. The results are evaluated based on their correlation coefficients and relative error. Finally, the application of horizontal-to- vertical irradiance mapping is demonstrated using the case of an office building at Vienna University of Technology.
Indoor Environmental Conditions in New York City Public School Class-rooms – A Survey
- J L Sze
J.L. Sze, Indoor Environmental Conditions in New York City Public School Class-rooms – A Survey, Harvard University, Cambridge, MA, 2009.
Occupancy Data for Thermal Calculations in Non-Domestic Buildings
- Oscar Faber
Oscar Faber Associates, Occupancy Data for Thermal Calculations in Non-Domestic Buildings, Building Research Establishment, 1992, Contract: F3/31158.
Effectiveness of dynamic daylighting. Post occupancy evaluation of a higher Ed building
- J Theodorson
- J Day
J. Theodorson, J. Day, Effectiveness of dynamic daylighting. Post occupancy evaluation of a higher Ed building, in: Proceedings of PLEA 2011 – Architecture and Sustainable Development, Louvain-la-Neuve, Belgium, 2011.
Window blinds as a potential energy saver – a case study
- A I Rubin
- B L Collins
- R L Tibbott
A.I. Rubin, B.L. Collins, R.L. Tibbott, Window blinds as a potential energy saver – a case study, in: NSB Building Science Series 112, National Bureau of Standards, Washington, DC, 1978, May.
Using daylighting controls in offices? Post occu-pancy study about their integration with the electric lighting
- E Cunill
- R Serra
- M Wilson
E. Cunill, R. Serra, M. Wilson, Using daylighting controls in offices? Post occu-pancy study about their integration with the electric lighting, in: Proceedings of PLEA 2007 – Wind Sun and Architecture, Singapore, 2007.
European Building Automation Systems Market: Paving the Way for Smart and Energy Efficient Buildings
- Frost
- Sullivan
Frost & Sullivan, European Building Automation Systems Market: Paving the Way for Smart and Energy Efficient Buildings, Frost & Sullivan, London, UK, 2011, M709-19, August.
Control of Solar Shading
- P Littlefair
P. Littlefair, Control of Solar Shading, BRE Environmental Engineering Centre, 2002, September.
Daylighting nomographs revisited – rules of thumb to predict energy savings from photocell controlled dimming systems, in: Sim-Build
- R Manudhane
- C F Reinhar
R. Manudhane, C.F. Reinhar, Daylighting nomographs revisited – rules of thumb to predict energy savings from photocell controlled dimming systems, in: Sim-Build 2010, New York, NY, 2010.
Questions Regarding Warema Climatronic Factory Sun Control Set-tings
- A Wicha
A. Wicha, Questions Regarding Warema Climatronic Factory Sun Control Set-tings, 2011, October.
Commissioning and Verification Pro-cedures for the Automated Roller Shade System at The New York Times Headquarters
- E Lee
- R Clear
- G Ward
- L Fernandes
E. Lee, R. Clear, G. Ward, L. Fernandes, Commissioning and Verification Pro-cedures for the Automated Roller Shade System at The New York Times Headquarters, New York, New York, Lawrence Berkeley National Laboratory, Berkeley, CA, 2007, May.
Findings from the New York Times MechoShade System User Over-rides
- J Ashmore
J. Ashmore, Findings from the New York Times MechoShade System User Over-rides, 2011, October.