A high luminance contrast between windows and surrounding surfaces can increase the risk of disco... more A high luminance contrast between windows and surrounding surfaces can increase the risk of discomfort glare, which can diminish office workers' satisfaction and productivity. Accordingly, it can lead to occupant interventions, such as drawing window blinds or increasing electric light levels, which are intended to enhance indoor visual comfort but counterproductively act to increase energy consumption. Increasing the luminance of the areas surrounding the windows using a supplementary lighting system, such as wall-washing with light emitting diode (LED) linear luminaires, could reduce discomfort glare arising from windowed walls. This paper reports on the results of a study in a typical office room in Brisbane, Australia. The outcomes of this study indicate that creating a luminance contrast of between 11:1 and 12:1 on the window wall in an office room with a 45% window-to-exterior-wall ratio using a supplementary LED system leads to improved subjective assessments of window appearance. The results suggest that such an enhancement could significantly reduce discomfort glare from windows, as well as diminishing the likelihood of the users intending to turn on the ceiling lights or to move the blinds.
Proceedings of the Asia-Pacific Lighting Systems Workshop 2015, May 2015
Vertical windows are the most common and simplest method to introduce daylight to interior spaces... more Vertical windows are the most common and simplest method to introduce daylight to interior spaces of office buildings, while also providing a view and connection to the outside. However, high contrast ratios between windows and surrounding surfaces can cause visual discomfort for occupants and can negatively influence their health and productivity. Consequently, building occupants may try to adapt their working environment through closing blinds and turning on lights in order to improve indoor visual comfort. Such interventions defeat the purpose of daylight harvesting systems and can increase the forecast electric lighting consumption in buildings that include such systems. A simple strategy to prevent these problematic consequences is to reduce the luminance contrasts presented by the window wall by increasing the luminance of areas surrounding the window through the sparing use of energy-efficient supplementary lighting, such light emitting diodes (LEDs). This paper presents the result of a pilot study in typical office in Brisbane, Australia that tests the effectiveness of a supplementary LED lighting system. The study shows an improvement in the appraisal of the visual environment is achieved using the supplementary system, along with up to 88% reductions in luminance contrast at the window wall. Also observed is a 36% reduction in the likelihood of user interventions that would increase energy usage. These results are used as the basis of an annual energy simulation of the test office and indicate that supplementary systems could be used to save energy beyond what is typically realised in side lit office spaces.
Glare indices have yet to be extensively tested in daylit open plan offices, as such there is no ... more Glare indices have yet to be extensively tested in daylit open plan offices, as such there is no effective method to predict discomfort glare within these spaces. This study into discomfort glare in open plan green buildings targeted full-time employees, working under their everyday lighting conditions. Three green buildings in Brisbane were used for data collection, two were Green Star accredited and the other contained innovative daylighting strategies. Data were collected on full-time employees, mostly aged between 30 and 50 years, who broadly reflect the demographics of the wider working population in Australia. It was discovered 36 of the 64 respondents experienced discomfort from both electric and daylight sources at their workspace.
The study used a specially tailored post-occupancy evaluation (POE) survey to help assess discomfort glare. Luminance maps extracted from High Dynamic Range (HDR) images were used to capture the luminous environment of the occupants. These were analysed using participant data and the program Evalglare.
The physical results indicated no correlation with other developed glare metrics for daylight within these open plan green buildings, including the recently developed Daylight Glare Probability (DGP) Index. The strong influence of vertical illuminance, Ev in the DGP precludes the mostly contrast-based glare from windows observed in this investigation from forming a significant part of this index. Furthermore, critical assessment of the survey techniques used are considered. These will provide insight for further research into discomfort glare in the endeavour to fully develop a suitable glare metric.
A high contrast ratio between windows and surrounding walls may lead to office workers visual dis... more A high contrast ratio between windows and surrounding walls may lead to office workers visual discomfort that could negatively affect their satisfaction and productivity. Consequently, occupants may try to adapt their working environment by closing blinds and/ or turning on the lights to enhance indoor visual comfort, which can reduce predicted energy savings. The hypothesis of this study is that reducing luminance contrast ratio on the window wall will improve window appearance which potentially will reduce visual discomfort and decrease workers interventions. Thus, this PhD research proposes a simple strategy to diminish the luminance contrast on the window wall by increasing the luminance of the areas surrounding the windows using supplementary light emitting diode (LED) systems. To test the hypothesis, this investigation will involve three experiments in different office layouts with various window types and orientations in Brisbane, Australia. It will assess user preferences for different luminance patterns in windowed offices featuring flexible, low-power LED lighting installations that allows multiple lighting design options on the window wall. Detailed luminance and illuminance measures will be used to match quantitative lighting design assessment to user preferences.
The international focus on embracing daylighting for energy efficient lighting purposes and the c... more The international focus on embracing daylighting for energy efficient lighting purposes and the corporate sector’s indulgence in the perception of workplace and work practice “transparency” has spurned an increase in highly glazed commercial buildings. This in turn has renewed issues of visual comfort and daylight-derived glare for occupants. In order to ascertain evidence, or predict risk, of these events; appraisals of these complex visual environments require detailed information on the luminances present in an occupant’s field of view. Conventional luminance meters are an expensive and time consuming method of achieving these results. To create a luminance map of an occupant’s visual field using such a meter requires too many individual measurements to be a practical measurement technique. The application of digital cameras as luminance measurement devices has solved this problem. With high dynamic range imaging, a single digital image can be created to provide luminances on a p...
Living and Learning: Research for a Better Built Environment, 49th International Conference of the Architectural Science Association, 2015
High contrast ratios between windows and surrounding surfaces could cause reduced visibility
or d... more High contrast ratios between windows and surrounding surfaces could cause reduced visibility or discomfort for occupants. Consequently, building users may choose to intervene in lighting conditions through closing blinds and turning on the lamps in order to enhance indoor visual comfort. Such interventions increase projected electric lighting use in buildings. One simple method to prevent these problematic issues is increasing the luminance of the areas surrounding to the bright surface of windows through the use of energy-efficient supplementary lighting, such Light Emitting Diodes (LEDs). This paper reports on the results of a pilot study in conventional office in Brisbane, Australia. The outcomes of this study indicated that a supplementary LED system of approximately 18 W could reduce the luminance contrast on the window wall from values in the order of 117:1 to 33:1. In addition, the results of this experiment suggested that this supplementary strategy could increase the subjective scale appraisal of window appearance by approximately 33%, as well as reducing the likelihood of users’ intention to turn on the ceiling lights by about 27%. It could also diminish the likelihood of occupants’ intention to move the blind down by more than 90%.
A high luminance contrast between windows and surrounding surfaces can increase the risk of disco... more A high luminance contrast between windows and surrounding surfaces can increase the risk of discomfort glare, which can diminish office workers' satisfaction and productivity. Accordingly, it can lead to occupant interventions, such as drawing window blinds or increasing electric light levels, which are intended to enhance indoor visual comfort but counterproductively act to increase energy consumption. Increasing the luminance of the areas surrounding the windows using a supplementary lighting system, such as wall-washing with light emitting diode (LED) linear luminaires, could reduce discomfort glare arising from windowed walls. This paper reports on the results of a study in a typical office room in Brisbane, Australia. The outcomes of this study indicate that creating a luminance contrast of between 11:1 and 12:1 on the window wall in an office room with a 45% window-to-exterior-wall ratio using a supplementary LED system leads to improved subjective assessments of window appearance. The results suggest that such an enhancement could significantly reduce discomfort glare from windows, as well as diminishing the likelihood of the users intending to turn on the ceiling lights or to move the blinds.
Proceedings of the Asia-Pacific Lighting Systems Workshop 2015, May 2015
Vertical windows are the most common and simplest method to introduce daylight to interior spaces... more Vertical windows are the most common and simplest method to introduce daylight to interior spaces of office buildings, while also providing a view and connection to the outside. However, high contrast ratios between windows and surrounding surfaces can cause visual discomfort for occupants and can negatively influence their health and productivity. Consequently, building occupants may try to adapt their working environment through closing blinds and turning on lights in order to improve indoor visual comfort. Such interventions defeat the purpose of daylight harvesting systems and can increase the forecast electric lighting consumption in buildings that include such systems. A simple strategy to prevent these problematic consequences is to reduce the luminance contrasts presented by the window wall by increasing the luminance of areas surrounding the window through the sparing use of energy-efficient supplementary lighting, such light emitting diodes (LEDs). This paper presents the result of a pilot study in typical office in Brisbane, Australia that tests the effectiveness of a supplementary LED lighting system. The study shows an improvement in the appraisal of the visual environment is achieved using the supplementary system, along with up to 88% reductions in luminance contrast at the window wall. Also observed is a 36% reduction in the likelihood of user interventions that would increase energy usage. These results are used as the basis of an annual energy simulation of the test office and indicate that supplementary systems could be used to save energy beyond what is typically realised in side lit office spaces.
Glare indices have yet to be extensively tested in daylit open plan offices, as such there is no ... more Glare indices have yet to be extensively tested in daylit open plan offices, as such there is no effective method to predict discomfort glare within these spaces. This study into discomfort glare in open plan green buildings targeted full-time employees, working under their everyday lighting conditions. Three green buildings in Brisbane were used for data collection, two were Green Star accredited and the other contained innovative daylighting strategies. Data were collected on full-time employees, mostly aged between 30 and 50 years, who broadly reflect the demographics of the wider working population in Australia. It was discovered 36 of the 64 respondents experienced discomfort from both electric and daylight sources at their workspace.
The study used a specially tailored post-occupancy evaluation (POE) survey to help assess discomfort glare. Luminance maps extracted from High Dynamic Range (HDR) images were used to capture the luminous environment of the occupants. These were analysed using participant data and the program Evalglare.
The physical results indicated no correlation with other developed glare metrics for daylight within these open plan green buildings, including the recently developed Daylight Glare Probability (DGP) Index. The strong influence of vertical illuminance, Ev in the DGP precludes the mostly contrast-based glare from windows observed in this investigation from forming a significant part of this index. Furthermore, critical assessment of the survey techniques used are considered. These will provide insight for further research into discomfort glare in the endeavour to fully develop a suitable glare metric.
A high contrast ratio between windows and surrounding walls may lead to office workers visual dis... more A high contrast ratio between windows and surrounding walls may lead to office workers visual discomfort that could negatively affect their satisfaction and productivity. Consequently, occupants may try to adapt their working environment by closing blinds and/ or turning on the lights to enhance indoor visual comfort, which can reduce predicted energy savings. The hypothesis of this study is that reducing luminance contrast ratio on the window wall will improve window appearance which potentially will reduce visual discomfort and decrease workers interventions. Thus, this PhD research proposes a simple strategy to diminish the luminance contrast on the window wall by increasing the luminance of the areas surrounding the windows using supplementary light emitting diode (LED) systems. To test the hypothesis, this investigation will involve three experiments in different office layouts with various window types and orientations in Brisbane, Australia. It will assess user preferences for different luminance patterns in windowed offices featuring flexible, low-power LED lighting installations that allows multiple lighting design options on the window wall. Detailed luminance and illuminance measures will be used to match quantitative lighting design assessment to user preferences.
The international focus on embracing daylighting for energy efficient lighting purposes and the c... more The international focus on embracing daylighting for energy efficient lighting purposes and the corporate sector’s indulgence in the perception of workplace and work practice “transparency” has spurned an increase in highly glazed commercial buildings. This in turn has renewed issues of visual comfort and daylight-derived glare for occupants. In order to ascertain evidence, or predict risk, of these events; appraisals of these complex visual environments require detailed information on the luminances present in an occupant’s field of view. Conventional luminance meters are an expensive and time consuming method of achieving these results. To create a luminance map of an occupant’s visual field using such a meter requires too many individual measurements to be a practical measurement technique. The application of digital cameras as luminance measurement devices has solved this problem. With high dynamic range imaging, a single digital image can be created to provide luminances on a p...
Living and Learning: Research for a Better Built Environment, 49th International Conference of the Architectural Science Association, 2015
High contrast ratios between windows and surrounding surfaces could cause reduced visibility
or d... more High contrast ratios between windows and surrounding surfaces could cause reduced visibility or discomfort for occupants. Consequently, building users may choose to intervene in lighting conditions through closing blinds and turning on the lamps in order to enhance indoor visual comfort. Such interventions increase projected electric lighting use in buildings. One simple method to prevent these problematic issues is increasing the luminance of the areas surrounding to the bright surface of windows through the use of energy-efficient supplementary lighting, such Light Emitting Diodes (LEDs). This paper reports on the results of a pilot study in conventional office in Brisbane, Australia. The outcomes of this study indicated that a supplementary LED system of approximately 18 W could reduce the luminance contrast on the window wall from values in the order of 117:1 to 33:1. In addition, the results of this experiment suggested that this supplementary strategy could increase the subjective scale appraisal of window appearance by approximately 33%, as well as reducing the likelihood of users’ intention to turn on the ceiling lights by about 27%. It could also diminish the likelihood of occupants’ intention to move the blind down by more than 90%.
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The study used a specially tailored post-occupancy evaluation (POE) survey to help assess discomfort glare. Luminance maps extracted from High Dynamic Range (HDR) images were used to capture the luminous environment of the occupants. These were analysed using participant data and the program Evalglare.
The physical results indicated no correlation with other developed glare metrics for daylight within these open plan green buildings, including the recently developed Daylight Glare Probability (DGP) Index. The strong influence of vertical illuminance, Ev in the DGP precludes the mostly contrast-based glare from windows observed in this investigation from forming a significant part of this index. Furthermore, critical assessment of the survey techniques used are considered. These will provide insight for further research into discomfort glare in the endeavour to fully develop a suitable glare metric.
or discomfort for occupants. Consequently, building users may choose to intervene in lighting conditions
through closing blinds and turning on the lamps in order to enhance indoor visual comfort. Such
interventions increase projected electric lighting use in buildings. One simple method to prevent these
problematic issues is increasing the luminance of the areas surrounding to the bright surface of windows
through the use of energy-efficient supplementary lighting, such Light Emitting Diodes (LEDs). This paper
reports on the results of a pilot study in conventional office in Brisbane, Australia. The outcomes of this
study indicated that a supplementary LED system of approximately 18 W could reduce the luminance
contrast on the window wall from values in the order of 117:1 to 33:1. In addition, the results of this
experiment suggested that this supplementary strategy could increase the subjective scale appraisal of
window appearance by approximately 33%, as well as reducing the likelihood of users’ intention to turn
on the ceiling lights by about 27%. It could also diminish the likelihood of occupants’ intention to move
the blind down by more than 90%.
The study used a specially tailored post-occupancy evaluation (POE) survey to help assess discomfort glare. Luminance maps extracted from High Dynamic Range (HDR) images were used to capture the luminous environment of the occupants. These were analysed using participant data and the program Evalglare.
The physical results indicated no correlation with other developed glare metrics for daylight within these open plan green buildings, including the recently developed Daylight Glare Probability (DGP) Index. The strong influence of vertical illuminance, Ev in the DGP precludes the mostly contrast-based glare from windows observed in this investigation from forming a significant part of this index. Furthermore, critical assessment of the survey techniques used are considered. These will provide insight for further research into discomfort glare in the endeavour to fully develop a suitable glare metric.
or discomfort for occupants. Consequently, building users may choose to intervene in lighting conditions
through closing blinds and turning on the lamps in order to enhance indoor visual comfort. Such
interventions increase projected electric lighting use in buildings. One simple method to prevent these
problematic issues is increasing the luminance of the areas surrounding to the bright surface of windows
through the use of energy-efficient supplementary lighting, such Light Emitting Diodes (LEDs). This paper
reports on the results of a pilot study in conventional office in Brisbane, Australia. The outcomes of this
study indicated that a supplementary LED system of approximately 18 W could reduce the luminance
contrast on the window wall from values in the order of 117:1 to 33:1. In addition, the results of this
experiment suggested that this supplementary strategy could increase the subjective scale appraisal of
window appearance by approximately 33%, as well as reducing the likelihood of users’ intention to turn
on the ceiling lights by about 27%. It could also diminish the likelihood of occupants’ intention to move
the blind down by more than 90%.