Using Mashrabiya to enhance daylighting and privacy in girls’ schools in Saudi Arabia

by Ahmad Kotbi, Welsh School of Architecture, Cardiff University, UK

The hot arid desert areas are endowed with abundance of clear skies and high temperature. Thus, the sunlight passing through can increase the temperature of interior spaces intensely and could result in an uncomfortable visual environment due to glare and poor uniformity ratios. Therefore, most historical and vernacular buildings in the desert environment have small windows to reduce penetration of sunlight. To be able to use bigger windows they introduced a shading device called “Mashrabiya” an external perforated solar screen that is fixed in front of the window to control solar penetration, it is found in vernacular examples in many places with desert environment. This screen has served also a social function of maintaining privacy which is an important issue in Islamic cultures. This latter aspect explains the spread of this device around the world wherever Muslims exist, from Moorish Spain in the West through North Africa and Middle East to India in the East.

In Saudi Arabia the privacy issue for women is of significant importance as the country follows an Islamic law which specifies that women should be covered when in the presence of unrelated men. For his reason women wear a black robe called “Abaya”. They can only remove Abaya in women-only events, their private homes or in building occupied solely by women, such as girls’ schools and colleges. In these buildings the windows are totally covered to maintain privacy, which has an impact on access to daylight and to external views. This work is looking at ways of overcoming these shortfalls, through the adaptation of Mashrabiya in building facades.

The performance of Mashrabiya is affected by many parameters and past research has examined the screen perforation rate, depth ratio, shape, reflectivity of color, aspect ratio of openings, tilt and rotation angles. Some previous studies have already investigated the effect of these parameters of Mashrabiya on the daylight and energy performance in residential spaces. However, results would be different for education spaces, due to different illuminance requirements and different window-to-wall ratio between residential and education spaces.

Moreover, no qualitative study is known to the author that examines the effectiveness of different Mashrabiya configurations on privacy. The aim of this thesis is to investigate the influence of the various parameters of perforated solar screen elements, such as Mashrabiya, on daylight levels and privacy in existing girls’ schools in Saudi Arabia.
This presentation will look at preliminary results of in-situ lux levels monitoring at selected classrooms in girls’ schools in Riyadh. The measurements are taken at different times of the day with no artificial lighting in use. The sample includes different classroom configurations and window treatments and is aimed to be used as a reference point to the research that will be undertaken in the future for the purpose of this PhD study. The results are analyzed and compared to standards and minimum requirements.

Energy saving and wellbeing with light

by Alessia Pedace, University of Palermo, Technical, Environmental Physics Department of Energy, Italy

In recent years one of the main goal in the construction industry has been the reduction of energy consumptions, which has to be achieved also by increasing the global efficiency of systems and therefore lighting plays a relevant role. In more detail, to reduce lighting related energy consumptions, the efficiency of electric lighting systems has to be improved (for example, by replacing lighting sources and/or using control strategies). However the best strategy to achieve relevant energy savings is to allow an adequate entrance of daylight, avoiding discomfort phenomena, and to design the electric lighting system according to daylight availability. Therefore daylight availability should be evaluated in the design phase; to do so, dynamic daylight simulations can be performed through software. Usually these simulations are carried out for a year using a weather data file which characterize the climate of the design location. However differences in the results obtained using different software and/or weather data files have not been widely investigated. Therefore a part of this PhD project was dedicated to a collaboration with another research assistant to analyze such differences [1].

Anyway the reduction of energy consumptions cannot be performed at the expense of users’ comfort. Indeed lighting requirements set by standards to perform visual tasks should be fulfilled but it is important to consider that both daylight and electric light have the ability to influence non-visual responses. This term indicates a wide range of light-induced effects which are not linked to vision, such as heart rate variations, melatonin suppression, changes in mood and many others. Therefore light has a strong impact on health and wellbeing and the evaluation of such effects should be introduced in the design practice. To do so, the characteristics of the light that reaches an user’s eyes, such as intensity, spectral distribution, etc., should be evaluated. For this reason, this PhD project mainly focuses on the analysis of the characteristics of both daylight and electric light at users’ eye level [2,3,4,5].

The final product of this research should be the development of design guidelines that help designers balance between users’ comfort and energy saving requirements.

REFERENCES
[1] Bellia L, Pedace A, Fragliasso F. The role of weather data files in Climate-based Daylight Modeling. Solar Energy 2015; 112: 169-182.
[2] Bellia L, Pedace A, Barbato G. Indoor artificial lighting: Prediction of the circadian impact of different spectral power distributions. Lighting Research and Technology 2014; 46(6): 650-660.
[3] Bellia L, Pedace A, Barbato G. (2014). Winter and summer analysis of daylight characteristics in offices. Building and Environment, 81, 150-161.
[4] Bellia L, Pedace A, Barbato G. Daylighting offices: A first step toward an analysis of photobiological effects for design practice purposes. Building and Environment 2014; 74: 54-64.
[5] Bellia L, Pedace A, Barbato G. Lighting in educational environments: An example of a complete analysis of the effects of daylight and electric light on occupants. Building and Environment 2013; 68: 50-65.

Determination of the dynamic range for non-visual effects of daylight for spectral sky models in urban structures

by Aicha Diakite, Technische Universität Berlin, Germany

In line with the UN report “World Urbanization Prospects: The 2011 Revision” more than half of the world’s population already lives in cities. Within the next few years the urban population will increase dramatically. According to the United Nation’s estimates the number of city dwellers will nearly double in 2050. The rapid demographic change, the fast growing urbanization and the expeditious densification of the cities form new spatial and social framework conditions for urban planning. Therefore there is among other a growing need for research on lighting master planning with daylight. Up to date, in the consideration of daylighting master planning as a sustainable urban design strategy, energy optimization is typically the only guideline and main purpose. Yet, considering biological, psychological and physiological needs of the citizens, the performance criteria indicate that colorimetric characteristics play an essential role. Hence the need to factor in the spectral information of daylight, next to the illuminance level and the emphasis on the interdependence between the performance criteria, in order to realize healthy and sustainable urban environments.

This dissertation aims at developing a parametric design tool, in particular to outline the dynamic range for non-visual effects of daylight including spectral sky models and consequently to allow a better impact assessment of designing the urban space with daylight. The study investigates the relevant performance criteria and design parameters in the urban planning and presents a novel approach describing sky models based on the spectral information. Furthermore it examines how to implement the spectral data in the spatial design and how to translate the results into a design tool.

The significant performance criteria and design parameters are determined based on literature survey and case studies. The implemented spectral sky models are based on the spatially resolved spectral power distribution measurements data generated at the Technical University of Berlin. The analysis of the data sets has three goals: to create, to verify and to simplify the spectral sky models. The main emphasis thereby is the practical applicability of the sky models in an urban planning process.

The findings of this study are meant to supports the design of sustainable daylighting master plans for cities, by defining the colorimetric characterization of the daylight in the urban structure and subsequently assessing the impact of daylight on non-visual aspects in urban settings.

Keywords: daylighting master plan, urban density, daylighting design, spectral sky models, colorimetric characterization

The Potential for Green Façades in the Built Environment and their Effect on the Transmittance of Natural Light

by Aimee L Desert, University of Sheffield, UK

With the continued focus on improving the sustainability of the built environment green façades have a substantial amount of unrealised potential; their contribution to the built environment goes far beyond simply enhancing the aesthetics of the streetscape. They have already been proven to improve the thermal properties of the building envelope and this project looks to investigate their shading performance and whether they can replace current artificial shading devices. The key advantages of a deciduous green façade as a shading device are only apparent when it is considered over a complete 12 month cycle as the variation in leaf cover alters the properties of the façade and a number of current studies overlook this. A mathematical model is developed using MATLAB to analyse the transformations that occur on incident rays of sunlight and daylight when they pass through a green façade. Daylight and sunlight are modelled separately in order to allow the different properties of each incident light type to be taken into consideration, the model clearly shows how there is a clear discrepancy between the way in which daylight and sunlight are effected by the green façade. Additionally the model accounts for the time of year allowing a complete conclusion to be drawn. The results of this modelling allow for a series of comparisons to be made between the effects of the green façade on natural light compared to a traditional façade as well as its performance as an adaptive shading device in comparison to artificial shading methods and devices. Initial calculations of daylight factor and internal illuminance indicate that a deciduous green façade can act as an effective bioshading device, adapting over the course of the year and its performance is equal, if not better, than the current artificial alternatives.

Key Terms. Facade; Vegetation; Daylight; Urban; Green

A simulation-based, adaptive, shading control algorithm

by Angelina Katsifaraki, Fraunhofer-Institut für Solare Energiesysteme ISE, Germany

The need for automized shading control in commercial buildings is becoming increasingly important not only for the visual comfort of the employees, but also for improving the energy performance of the building. The most commonly available control strategies apply on traditional, flat or curved Venetian blinds and are rather simple since they function on illuminance set-points or schedules. More sophisticated systems use cut-off control in order to block the direct component of solar radiation in the room. Control strategies taking vertical illuminance or glare into account, though popular as an idea, are not commercialized. The reason lies mainly in the difficulties of the measurement procedures and the need of a large number of sensors that complicates the commissioning process of the controller. Finally, commercial control algorithms, despite their benefits, do not take into account the occupant’s subjective sense of visual comfort or the occupant’s need for visual contact with the outside. This often results to the poor acceptance of the controller from the users and leads them to overwrite the algorithm.

This PhD research focuses on the development of a simulation-based, adaptive shading controller. The controller uses a Radiance-based building model to run daylight and glare simulations using the three phase method in order to calculate the horizontal illuminance on the working surface and the vertical illuminance at the eye and computer screen levels. Based on these calculations, it selects the optimal shading configuration according to a rule based control algorithm. Additionally, it adapts to the user wishes by using fuzzy logic to characterize the user’s perception of visual comfort based on glare and illumination conditions in the room while it favors view out when possible. Finally, it contributes to the thermal comfort of the room by controlling the acceptance and rejection of solar gains depending on the season and the room temperature.

The described controller has many benefits over conventional systems since it takes into account glare and daylighting in an office space without requiring a complicated installation of illuminance sensors except from a rather simple one for calibration purposes. By using the three phase method, the simulation time is short enough and the computational requirements are low so it can be used in a prototype installation Moreover, the system can be quite flexible as to the choice of the shading device as opposed to traditional shading control systems. Finally, the control algorithm puts weight on the user wishes by adjusting to the user preferences and also favoring view out.

Energy Saving by Using Daylight in Town Planning

by Bengt Sundborg, KTH, Royal Institute of Technology, Sweden

This project focuses on saving energy. Town planning can contribute with effective typologies in grouping of buildings, form of the blocks, street grids, etc. The aim with this project is to present good examples of existing and even some new urban forms.

The geometry of the street grid, of the courtyards and of the squares together with the height of the buildings is important for the amount of daylight. Fundamental facts from research in urban morphology and daylighting are an important base for the project as a BRE report by Paul Littlefair and a recently published report from LSE Cities/EIFER. An example of energy savings in town planning is the different spacing between parallel houses studied by DTU in Denmark. To extend the distance between parallel houses naturally increases the amount of daylight but it also adds a higher cost for the land.

This project compares different solutions in the built environment with the same density and the same cost for the land. If the daylight is accessible for a longer time of the day, both indoors and outdoors, the period of need for electric light will decrease. The expected savings for delaying the time for switching on the electric light in the evenings and for bringing forward the time for switching off the light in the early morning is probably not so high but in the long run it has relevance.

In this ongoing research in daylight, computer simulations are performed in order to calculate the savings of energy using one type of settlement instead of another. Different patterns for district and blocks are evaluated. The amount of daylight will be calculated with in different street grids (see Figure 1). The first photo (left) is a typical rectangular street grid which gives low angled skylight from four different directions. The photo on the right shows an irregular organic street grid with difficulties for direct sunlight and even for diffuse skylight to reach the ground with in the bending and narrow streets. The picture in the middle is an example of a new type of grid with more possibilities for daylight.

Figure 1. The street grid is important for the distribution of daylight and here are three examples. The second grid (middle) has the best access to daylight. The third grid is the darkest but also has the largest variety of form of the urban blocks.

Figure 2. The protruding frames in this window unfortunately reduce both daylight and views.

Figure 3. (Left) In an acute corner of a courtyard  it is dark and there is lack of privacy. In an acute corner of a building it is difficult to  furnish internally. (Right) Chamfered corners of a building provide daylight and views. Moving the acute part of the building (left) into the courtyard will create a chamfered building.

The resulting paper for my PhD will include results for single buildings and separate building elements. The window in figure 2, with its protruding frame, and the corner of the building in figure 3, left and right, will be calculated regarding its consumption of electric energy. The final goal for the research is practical guidelines for “better” geometry in urban design.

Keywords Energy, building design, urban design, climate, daylight

Lux, lumen; thinking space metaphysically, from Newton to abstraction

by Corentin Haubruge, Université catholique de Louvain (UCL), Belgium

Based on a multiple nature postulate of daylight – either subject, medium or material – the thesis tends to underline some crucial inflexion points of the occidental light history between physics, painting, and architecture.

The thesis is based on a historical approach and tries to measure the influence from theoretical models and conceptions on artistic artefacts. If the architectural dimension is the aim of the study trough examining built lighted spaces, painting is first of all considered as a cultural revelator able to interact with science more quickly than construction art.

Hence the research first examines the influence of physic theories on paintings and built spaces. After that, some efforts are spent to analyze the metaphysical range of the light in those disciplines, trying to describe the link between space and light as they are not only represented, but also inhabited.

Our focus first lies on oil paintings from the 17th century, according to the classical modern scientific paradigms of this time, developed by Descartes and Newton. In this context, the Vermeer’s works are a subject of high interest for this period, admitting a link between painting of course, but also illuminated spaces, sciences, and metaphysics.

Another important step can be found during the 19th century, while some scientific models began, for the first time, to influence directly the painters, and the role of light. The Goethe or Chevreul’s light and color theories influence on Seurat or Monet’s works are indisputably worth of interest regarding the construction of the metaphysical role of light in space.

More recently, the art of Edward Hopper gives us new marks to study the relationship between light and inhabited spaces, trough the study of sunspots and cast shadows.

The analyse of the characteristics of painted light leads prima facie to a more metaphorical vocabulary compared to architecture, but doesn’t seem to be sufficient to articulate the relation between physics and space, because of the limited range of the bi-dimensionality of the paintings.

Archetypal built projects from any period, as they reveal the link between a dynamic daylight (lux) and a perception of signification (lumen), need to be analyzed, in plan to distinguish how architecture creates conditions of light and in a same way, how light creates architectural or space conditions, giving us to think, as much as it gives us to see.

Applicability of Climate-Based Daylight Modelling

by Eleonora Brembilla, Loughborough University, UK

Climate-Based Daylight Modelling (CBDM) has recently reshaped the daylighting practice, moving forward from the traditional static evaluation of buildings luminous environment (i.e. Daylight Factor and shading analyses) and introducing annual models based on the representative climate of the actual location. This new methodology developed thanks to several individual experts’ contribution, generating a high number of distinctive approaches, and made use of the available input data, often those used for the more established thermal simulations and DF calculations. Since it has been introduced in guidelines and building regulations, however, the definition of specific targets to comply with created the need for common, comparable procedures and quality checks on the required inputs.

The research aims at analysing the different approaches currently used to perform CBDM evaluations, understanding whether they are fit for the desired purpose of realistically predicting daylight behaviour in buildings. The methods considered for the study are some of the ones most used by daylighting experts and as back-end tools in commercial building performance simulation programs, all of which use the Radiance system as simulation engine (i.e. 2-, 3- and 5-phase methods, DIVA-for-Rhino/Daysim). They are being evaluated against another method, which has been scientifically validated against real measurements, now known as 4-component method. Additionally, the spaces chosen for the project are modelled on real case study classrooms that are the subject of another parallel research, which will collect data about their internal luminous environment using HDR captures over a continuous period of time, while the external luminous data will be recorded by a nearby weather station.

Once all the resulting datasets from different software and from the monitoring of the case studies have been analysed and compared together, it will be possible to draw conclusions that would inform designers on how to get the best from a climate-based daylight model.

The research project has been presented at the LumeNet Workshop 2014 in Berlin and at the 13th Radiance Workshop in London.

The impact of innovative lighting technologies in hospitals on staff performance

by Emy Apodoulianaki, Eindhoven University of Technology, Building Lighting Group, The Netherlands

Currently, an investigation on the healthcare system and its possible evolution to achieve sustainability in terms of costs, availability, and outcomes is ongoing. The formation of healing environments in hospitals has risen up in the agenda. A healing environment is defined as ‘a physical setting and organizational culture that supports patients and families through the stresses imposed by illness, hospitalization, medical visits, healing processes, and sometimes, even bereavement’ [1]. The goal is to engage patients in the conscious process of (self)-healing. Indeed, spaces are designed to be nurturing and therapeutic and, most importantly, to reduce stress. According to recent research findings, occupants’ health and wellbeing are affected by the building aspects. Nevertheless, limited evidence was found by previous studies on the impact of lighting on people and their performance [2]. Till recently, emphasis has mainly been given to patients’ prosperity. In this matter a direct correlation between staff and patient satisfaction was highlighted. The aim of the current study is to analyse staff performance by evaluating stress levels and alertness, both subjectively and objectively (by physiological data on a systematic basis). ). The study has a mix method design; consisting of a controlled study, proceeding by a systematic literature, qualitative research to investigated the current hospital situations: based on on-site observations, on interviews with staff and questionnaires. Overall, emphasis will be given on the staff’s perception of and reaction to both daylight and artificial lighting conditions (for example light levels and the colour of the light) through the day. Finally, outcomes are expected to be used in practice, as well as for further research. It is an innovative approach in the area of built environment conditions in hospitals that will facilitate a holistic design of healing environments.

[1] Huisman E.R.C.M. et al., 2012. Healing Environment: A review of the impact of physical environmental factors on users. Building and Environment 58, pp 70-80.
[2] Ulrich, R. et al., 2008. Review Of The Research Literature On Evidence-Based Healthcare Design. Health Environments Research and Design Journal, Vol. 1, No. 3.

Tools and methods for increasing natural lighting in building renovation design

by Federica Giuliani, Università La Sapienza, Italy

The current economic situation and the lack of space resources, has led us to reconsider the building heritage as an asset for improving quality of living and energy savings.

Concerning visual comfort, daylighting strategies could significantly improve the wellbeing of inhabitants and reduce electricity consumption. However, the integration of daylighting design within a renovation design, is a very hard task.

Nowadays a designer aiming at increasing natural lighting in a building renovation design, would face several problems.

First of all, he would not be able to evaluate the lighting situation. This is very common (in Italy) and it forces designers to rely on a specialist for any problem related to lighting and illumination. This appears to be the easiest solution, but it is often not the best one. Sometimes there is no lighting designer involved, and artificial lights are simply part of the general electrical design. As a consequence, daylighting design becomes subordinate to the architectural design, especially in minor projects, such as renovation ones.

Moreover, in existing buildings the choice of increasing artificial lights power is cheaper than foreseeing devices to be integrated in the facade or transforming the plans.

In addition the designer may find difficulties in choosing the right device to use. He could rely on technical data sheets, but those are very limited and one‐sided. How to choose between two devices? What influence does a device on spatial quality have? How important are secondary effects?

Last but not least, there is a deep gap between possibilities offered by Climate‐Based Design Modelling (CBDM) and building regulations requirements. On the one hand, there is a method that requires specific skills but leads to accurate evaluations. On the other hand, there is a minimum level of limited standards that do not require specific knowledge.

In conclusion, although renovation and redevelopment of urban heritage are important opportunities for improving quality in our cities, daylighting strategies hardly become part of those activities. The main reason is that it is not convenient: it requires a team work, it is not explicitly prescribed by legislation and usually a basic know‐how is missing.

The purpose of this research is to find a set of connections that can help designers to improve daylighting in their works on existing buildings.

In particular, the work focuses on the opportunity of using a communication form that could be suitable to architectural creative process ‐ that is not a linear process ‐ through the use of an Evidence Based Design (EBD) approach.

The goal is to build an archive of evidences (case studies) that shows different ways to approach the (day)lighting problem. The research moves from the idea that technical handbooks are full of rules of
thumb while the problem for an architect is to use creatively the knowledge gained in his work as a designer.

Scientific output is a guided selection process based on two databases (Evidences and Devices) aimed at choosing the best device in accordance with a reference design. An elementary software allows easy connections from user’s input data.

In order to properly understand every single step of daylighting design during a building renovation process, a complete renewal design on an existing nursery school has been carried out.

Adaptive Visual and Thermal Comfort

by Giorgia Chinazzo, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland

Increasing efforts are devoted to enhance and optimize the environmental comfort in buildings, as this aspect plays a major role in the affection of health, performance and general well-being of people. Indoor air quality, acoustic ambience, light and thermal conditions have been proved to be fundamental factors for the indoor environmental quality. Engineers must be aware of the effects of the interactions between these factors on the indoor comfort as people react simultaneously to diverse stimuli belonging to different sensorial fields and adapting their behaviors according to the associated conditions. Being able to know how these interactions influence the users’ comfort can lead to marked energy savings and positive influence on users’ productivity. Many studies have been conducted on the influence of each component on the overall comfort, but only few studies are available investigating the interaction between different comfort variables of different disciplines.

This research focuses on the interaction between visual and thermal comfort for building users in school environments, looking at the impact of different perceptive conditions on the productivity of the users and overall comfort. In particular, it analyzes the effect of visual variables on the perceived thermal comfort and of thermal variables on the perceived visual comfort, beside the mutual interaction of visual and thermal variables on the overall comfort appraisal. The study is based on fundamental concepts belonging to different branches of knowledge, ranging from engineering to psychology and physiology for the considered purpose. These disciplines come together in search for objective interactions between different comforts by means of experiments in realistic climate chamber or controlled field studies.

The goal of this study is to propose new guidelines for informing building designers on the interaction between visual and thermal variables and their influence on human comfort and productivity in the built environment. The results of this study will ultimately foster the development of control systems with the aim to achieve energy savings, increase user satisfaction as well as boost productivity.

The research has started in February 2015 under the supervision of Jan Wienold and Marilyne Andersen (expected end date: February 2018).

Architectural Strategies to Integrate Wellbeing and Health Effects of Daylight into Design of Primary Schools: a comparative analysis of exemplary case studies

by Jean-Denis Thiry, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland

Starting from an architect’s point of view, the aim of this doctoral research is to combine the daylight performance of educational spaces with a broader spatial, cultural, and historical approach. Through a rigorous study of school typologies, the geometry of their spaces, and their associated daylighting strategies, this work aims to connect design practitioners with aspects of health and well-being for the pupils, as far as these aspects are related to the quality of daylight.

The proposed methodology seeks to analyse a range of outstanding case studies from the masters of modern architecture, embodying architectural strategies specifically designed to ensure adequate illuminance levels in learning areas throughout the day. A selection of some singular primary schools will be established through a historical analysis which emphasizes the impact of hygienists’ principles – legacies of Modernism – on the evolution of plans and volumes of different school typologies in Switzerland and Europe, from 1950 to the present days.

An analysis of the selected case studies will be carried out using an innovative representation method of average illuminance received at eye-level and combined with a HLR model – currently under development at LIPID [1, 2] – which assesses the health potential of daylight using a dynamic approach. Through a validation of the simulated results using different in situ measurements and analyses following a specific protocol, we aim to accurately identify architectural criteria and propose strategies for achieving “circadian design”, more specifically those having a positive impact on the health and wellbeing of occupants. We will also carry out a comparative critical assessment of the buildings selected as case studies in the initial phase of this proposed research.

The goal is to positively influence decisions related to the design of naturally lit spaces, specifically in schools and according to their impact on health, wellbeing and student productivity. The methodology will be a complementary blend of observations, in situ measurements and qualitative and quantitative analyses, both in a simulated environment and in actual working conditions of the selected case studies.

Keywords: daylighting strategies; skylights; primary school typologies; hygienists principles; health and wellbeing; circadian architecture; field studies; simulation-based analysis.

References

[1] Amundadottir M.L., Hilaire M.A., Lockley S. W. and Andersen M., Modeling non visual responses to light: unifying spectral sensitivity and temporal characteristics in a single model structure. CIE Centenary Conference “Towards a New Century of Light”, Paris, France, 2013.

[2] Amundadottir M.L., Lockley S. W. and Andersen M., Simulation-based evaluation of non-visual responses to daylight: proof-of-concept study of healthcare re-design. BS 2013: 13th International Conference of the International Building Performance Simulation Association, Chambery, France, 2013.

Evaluating spatial ambiences through daylight variability, contrast and view

by Kynthia Chamilothori, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland

This research aims to give insight into the aesthetic aspect of the spatial and temporal diversity of light in space through experimental studies. By using empirical methods to establish a relationship of spatial contrast, daylight variability and view out with occupant preference and perception, we aim to link traditionally non-quantifiable aspects of daylight in space such as ambience with novel quantifiable metrics, validated in real space.

Daylight has an undeniable value in various aspects of architectural design, ranging from energy efficiency and user comfort to the perception of architectural space. Focusing on the current need for sustainable design, most contemporary daylighting metrics are either comfort-based, aiming on the prediction and avoidance of glare (Konis 2011), or task-based, emphasizing on the aspect of visual performance under daylighting conditions (Reinhart, Mardaljevic, and Rogers 2006). This approach dismisses the importance of daylight in the spatial experience of architectural design and its direct link with the perceptual qualities of lighting and has led to an evident absence of a performance indicator aiming to assess the aesthetic dimension of daylight (Cauwerts 2013).

The importance of contrast and luminance variability in the perceptual performance of space has been addressed in various studies (Veitch 2001; Parpairi et al. 2002; Kort and Smolders 2010; Rockcastle and Andersen 2014) however, there is no defined range of acceptable variability, especially regarding the spatial and temporal aspect of these light qualities. Furthermore, there is limited research concerning user preference and perception with regard to view out, a field inextricably linked to the evaluation of daylight, especially regarding the characteristics of the openings and their impact on human appraisal. Such results would allow for insights not only into the establishment of thresholds concerning view preference but also in the joint impact of daylight and view out, broadening our understanding on the complex relation between view, daylight and spatial experience.

The proposed project focuses on the development of reliable metrics to assess preference and perception related to daylight variability along with view out. We aim to the identification of a preferred range with regard to view out, according to different characteristics of the space’s openings as well as its function. Furthermore, this research will explore the influence of the perceptual effects of daylight such as daylight variability and contrast on the perceived spatial ambience. The ambience or atmosphere of a space refers to the experience and appraisal of the environment in relation to the subject, allowing for a more stable subjective evaluation variable (Vogels 2008). This study will be divided in two parts, namely the design and conduction of experiments in virtual space and the validation of the findings of the first study through real space experiments. By assessing both static and dynamic light situations, we aim to represent and evaluate a wide range of daylight and view conditions which can enable the emergence of patterns in the subject of preference and appraisal in the experience of architectural space.

Institutionalization of Sustainable Building

by Lara A Hale, Copenhagen Business School, Denmark

My research is qualitative, based significantly on primary data from semi-structured interviews, but also supplemented with event attendance, observations, and secondary data such as marketing materials. The topic is the institutionalization, and I have focused within this area on standards, in particular on the Active House approach. The overarching question guiding the research is: How are demonstrations strategically used support the institutionalization of sustainable building standards based on both quantitative and qualitative values?

VELUX has been instrumental in forming a research project based on the study of Sunlight House in Pressbaum, Austria; LichtAktiv Haus in Hamburg, Germany; and RenovActive in Brussels, Belgium (pre-construction phase). I’m a little over halfway through a three-year program (21 months as of April) and am currently moving from the data collection process to the follow-up interviews and data analysis. Data collection involved three-week research stays in each of the areas, allowing time for setting up appointments and “snowballing” – seeking out interesting actors to speak with based on the recommendations of interviewees. In total, I conducted 24 interviews, participated in the Active House Guidelines workshop and the 2013 and 2014 Active House Symposiums, and attended four building conferences: the 2014 Passive House Conference in Brussels; the 2014 Passive House Conference of Northern Germany outside of Hamburg; the 2015 Bauz! Conference in Vienna; and the 2014 World Sustainable Building Congress in Barcelona.

I have written a paper entitled “Commensuration and Legitimacy in Standards” which I will be presenting at the European Group for Organizational Studies Conference and the Academy of Management Conference this summer. Daylight has been a regular theme in my research, and surfaces also in this paper. Commensuration, the conversion of qualities into comparable quantitative data, is a ubiquitous but opaque process in standards. Daylight is commensurated in the Active House specifications, and it has been enlightening to hear discussions on the measurement and value of daylight from interviewees and conferences alike. Daylight is also an important dynamic in the relation between technology, people, and standards, the topic of my working paper – relating the building demonstrations to Science and Technology Studies (STS). It represents a pivotal point among comfort, health, aesthetics, and energy use. In preparation for the symposium, I have been coding my interviews for daylight, and hope to be able to share these insights with other researchers. I’m also curious to see the different ways other researchers perceive and apply daylight as a concept; and how they deal with measurement.

Investigating the MRSE/TAIR based metric for daylight design

by Longyu Guan, University College London (UCL), UK

My plan is to investigate the possibility of implementing some of the new lighting metrics, to be more specific (Cuttle’s) Mean Room Surface Exitance (MRSE), Target/Ambient Illuminance Ratio (TAIR) and Cubic Illuminance in daylight designs.

During my MSc Light and Lighting at UCL, I built a simplified daylighting model with my supervisor Peter Raynham and calculated some MRSE/TAIR values for a daylit space, as shown in Figures below.

Figure 1 gross TAIR distribution on horizontal planes (left) and vertical planes (right)

Theoretically the MRSE value can suggest the overall illumination adequacy of the daylit space, while the TAIR values will reveal the relative illuminance distribution pattern (Figure 1) and predict the perceived difference of a target object for any given location (Figure 2). In addition, because E_tgt=MRSE·TAIR, the absolute illuminance value on any planes/spots can also be easily calculated.

Figure 2 detailed TAIR pattern on specific planes & locations (left is on a horizontal plane; right is on a vertical plane)

Above MRSE/TAIR diagrams cover all the information that the daylight factor approach provides. The TAIR are actually quite similar to daylight factors, and they are essentially both illuminance ratios. However instead of comparing the target illuminance with external illuminance, TAIR compares the target illuminance with the internal “background illuminance” (MRSE). This allows more design values be derived from the MRSE/TAIR metrics. Rather than just evaluating the visual performance on a horizontal plane (daylight factor), the MRSE/TAIR approach enables lighting designers to devise the daylight distribution of entire space and create visual emphasis on significant objects.

Figure 3 illuminance vectors derived from cubic illuminance

Further, MRSE provides a method to calculate cubic illuminance, as Cuttle has suggested using the MRSE value as the indirect illuminance component and adding it equally to all the six faces of the cubic. Cubic illuminance can be used to calculate the illuminance vectors, which could reveal the “daylight flow” within the room (Figure 3), and the shadowing pattern can also be analysed. This allows designers to proceed with even more precise and advanced daylighting designs. Additionally, other useful values such as Cylindrical Illuminance, Hemispherical Illuminance and Scalar Illuminance can be derived from cubic illuminance. Those tools can add more depth to the daylight design, allowing a pre-determined daylit appearance being possibly engineered.

Implementing MRSE/TAIR concepts in daylight design may look promising. It breaks away from the traditional way of thinking daylight levels on a horizontal plane, to assessing the daylighting for the entire 3-dimention interior space. However, in the current stage, the sky models used (to calculate MRSE/TAIR values) are still the “old” CIE standard general sky models. These fixed sky models cannot truly represent the real sky conditions, as the real sky will vary greatly from day to day and from climate to climate. Therefore for the PhD project, I will integrate Climate Based Daylight Modelling (CBDM) and Ray-tracing lighting simulations, trying to re-create this daylighting model for much complicated daylighting scenarios. In end of the study, hopefully I will be able to propose a new daylight metric, together with design procedures for more advanced daylight designs.

The potential benefit of this PhD study could be summarised as:

• To propose a new daylight metric
• To propose an alternative daylight design procedure, allowing the devising of visual emphasis and other visual effects.
• To provide a better understanding of the relationship between different weather/climate and the interior daylight level
• To contribute the development of window designs
• To contribute the development of daylight simulation and calculations

A Study in Tectonics and Morphology for Nearly Zero Energy Architecture

by Marja Lundgreen, White arkitekter AB and KTH Royal Institute of Technology, Sweden

The focus in this licentiate is framed by the title; Nearly Zero Energy as a Design Parameter – A Study in Tectonics and Morphology for Nearly Zero Energy Architecture. The investigation is two sided; to investigate and demonstrate the potential in working with the relation between building physics and design to develop an approach to find architectural solutions for the nearly zero energy goals and to reflect on national legislation and standards and its relation to architectural form. The very coexistence between the architectural perspectives and strict natural science perspectives is a base for this thesis. Architectural research frames a knowledge production in its own right, but it is also transdisciplinary science by its nature reaching into the arts, the humanities, social sciences and natural sciences. A relevant polarity in the work at hand in my thesis is the relation between quantitative and qualitative assessments in the design process, tested through smaller inquiries. At present through one article to be sent to SASBEE, one conference paper presented at Energy Forum – Advanced building skins 2014 together with colleagues and an abstract for the Daylight conference together with a colleague.

The conference paper for Energy Forum describes an approach using research findings as rules of thumb in a competition, turning away from DF to DA in 2012 (when certification systems in Sweden still used DF) in order to work with quantitative tools more informative for the design process. Quantitative assessments are becoming appreciated as more and more important for the creation of sustainable architecture. Quantitative goals are designed in order to reach certain sustainability goals through legal frameworks, standards and certification systems. It is therefore of great importance to assess the base of the quantitative assessments in regards to the consequences on qualitative aspects of architecture. In my thesis this is not carried out on a general level, but rather on a detailed level starting with the first mentioned article, an article evaluating of the effects of the Swedish interpretation of Energy Performance of Buildings Directive (EPBD 2010/31/EC) on Swedish architectural praxis and presenting a proposal for alterations. The analysis relates to the premises set out in Guidelines for revising the Swedish Building Code by the Swedish National Board of Housing, Building and Planning (Boverket), stating that the Swedish Building Code is to be a performancebased regulation, not limiting choices in design, material and methods. A comparative analysis between the Code regulation on daylight in the health chapter and the energy chapter is vital for the analysis.

The interaction between qualitative and quantitative is an underflow in my thesis and complements the larger questions of how architecture, in terms of how knowledge production based on interrelations between building physics and architectural design within tectonics and morphology, can lead to near‐zero energy buildings that promote high quality environments for man.

Time of the Day, Temporal and Personal Variables and Task Difficulty in the Subjective Evaluation of Glare Sensation

by Michael Kent, The University of Nottingham, UK

Several indices have been developed to predict the subjective evaluation of glare sensation experienced by observers. However, if a large number of subjects were asked to express their perception of visual discomfort from different light sources characterised by similar glare indices, a wide spread of data would appear. This suggests that there must be other variables that influence the perceived level of visual discomfort other than those typically embedded in glare formulae (source luminance, source size, background luminance, and position index). Various studies have looked at how light influences the perceptual and metabolic system at different daily periods.

To test whether a potential relationship exists between time of the day and glare sensation, an investigation was set out. Thirty subjects were exposed to an artificial lighting source at four times of the day. The source luminance was progressively increased and subjects were required to give Glare Sensation Votes (GSVs) corresponding to the level of visual discomfort perceived. A statistical analysis of the data revealed a tendency towards greater tolerance to luminance increases as the day progresses. This trend was found not to be related to the confounding variable of learning. During the experiments, temporal variables and personal factors were also measured to analyse their influence on the reported levels of visual discomfort. Inferential testing of the data revealed a statistically and practically significant tendency towards greater tolerance to source luminance at all times of day for earlier chronotype subjects and for participants not having ingested caffeine. Conversely, no conclusive evidence was found for the effect of fatigue, sky condition, and prior light exposure on glare sensation throughout the day. In a follow-up series of experiments, twenty subjects were exposed to a constant artificial source luminance at various times of the day and gave GSVs whilst completing 12 visual tasks of various difficulty. The statistical analysis of glare responses confirmed the previously detected tendency towards greater tolerance to luminance increases as the day progresses. This variation in tolerance was found to be influenced by the difficulty in extracting information from the visual task, while being also potentially confounded by fatigue. The findings of this study suggest that time of the day, temporal and personal variables, together with difficulty of visual tasks presented to the observers, should be measured in conjunction to GSVs to explore the causes of scatter commonly associated with subjective evaluation of glare sensation and increase the predictive power of glare indices. Ongoing investigations, with larger sample sizes and in a test room with direct access to daylight, are deepening the analysis of the complexity of the influences detected.

Reference

Lockley, S.W. 2009. Circadian rhythms: Influence of light in humans. Encyclopaedia of Neuroscience, 2: 971-988.

Operational daylighting performance and daylight metrics in UK classrooms

by Nafsika Christa Drosou, Loughborough University, UK

The project at hand addresses the need to improve the understanding of how daylight is experienced by occupants. Moreover, it aims to establish the relationship between daylight metrics and daylight levels of the ‘live’ learning environment of UK classrooms.

A selection of secondary school classrooms are used as case studies and a mixed method quantitative and qualitative approach is applied. High Dynamic Range imaging is employed to quantify the luminous environment and lighting energy consumption, as well as to monitor the actions occupants take (blind use, electric light use) to improve or sustain visual comfort. Questionnaires, focus groups and interviews are used to investigate the occupants’ daylight perception, as well as the rationale behind their observed behaviour.

The association of qualitative and quantitative data will lead to the quantification of experienced daylight in ‘live’ learning environments and the identification of behavioural patterns that correspond to specific daylight design elements of the case study buildings. This will provide evidence for the assessment of the real world impact of specifying compliance with traditional daylight metrics. Findings of a parallel PhD project on climate based daylight modelling (CBDM), simulating the same case study classrooms, will enable a comparison between the luminous environments that result from the use of traditional versus CBDM metrics.

Implementation of daylight design strategies in urban planning – barriers to application in Poland

by Natalia Sokól, Faculty of Architecture, Department of Urban Design and Regional Planning, Gdansk University of Technology, Poland

This paper reflects on studies done in the area of daylight design methods with regard to principles that can be applied in architecture and urban planning strategies. The paper addresses barriers to the application of new daylight design methods in urban planning, and in particular discusses current Polish building regulations in the context of daylight design. The results of the pilot study (second questionnaire) carried out among 28 participants show a growing demand for better daylight education and an urgent need for revision of the existing outdated lighting recommendations in Poland. In conclusion, the pilot study (first survey) carried out among 54 students illustrates the importance of daylight as a natural resource considered essential in sustainable approaches to urban planning, and highlights the belief that daylight and electric light projects should be holistically integrated in the implementation of the town lighting plan.

This paper is a part of PhD research on daylight design within the contemporary urban texture, which focuses on the growing role of daylight in creating more sustainable residential architecture. One of the aims of this work is to identify how knowledge of daylight could help in the reconsideration of contemporary urban planning in Poland, especially with reference to a growing number of new urban residential areas. This PhD research discusses how daylight strategies should be implemented as design methods in architecture planning.

Polish regulation
The latest Polish daylight standard (PN-71/B-02380 Natural Interior Daylighting Code of Practice) was withdrawn without any replacement on 24.10.2005 (Turlej, 2012). This standard described general conditions of daylight distribution within interior spaces, Daylight Factor (DF) calculations, daylight coefficients, and DF values for different visual tasks as well as glass transmittance and reflectance values. The European Committee for Standardization CEN TC169 WG11 is working on a new European standard for daylight as Poland awaits the proposals (Turlej, 2012). Despite the lack of daylight standards, there are no national initiatives to produce such. The current valid light standards in Poland are: PN-EN 12464-1:2012 Light and Lighting – Lighting of Work Places – Part 1: Indoor Work Places and PN-EN 12665:2011 Light and Lighting. Basic terms and criteria for specifying lighting requirements. Daylight is mentioned in the building regulations.

The complex nature of daylight design suggests that recommendations and guidance are needed. Current Polish recommendations fail to precisely indicate what dynamic daylight metrics are needed to achieve better quality of daylight or what actions can be taken to achieve the lowest daylight criteria.

Barriers to implementation of daylight design strategies
From this study the barriers that emerged on the implementation of daylight design strategies in Poland are:

• inconsistency in urban residential plans
• deficiencies in residential stock and rising land prices that mainly drive new residential developments
• priorities in residential design that focus on quick delivery & profit, but not residential comfort
• lack of awareness that daylight design is a factor contributing to better living conditions
• lack of national daylight standards and guidelines
• very limited daylight guidelines in building regulations
• lack of national initiatives towards promoting daylight design as a sustainable design approach
• low quality of design solutions as an effect of gaps in education (lighting courses are offered in electrical engineering faculties)
• low awareness of daylight dynamic metrics and assessment methods among architects and urban planners

Selected conclusions
The overview of the Polish residential environment presented in this short study illustrates that daylight design strategies are not included in urban residential planning, especially when making decisions concerning urban density, building shape and height, and the location of open areas. One of the most important barriers to development in such a situation seems to be the fact that the design of residential areas focuses on the quick delivery of dwellings, and not on the quality of living spaces. Although daylight design is acknowledged in literature as a tool for fostering residents’ well-being, daylight design strategies are not common in practice. Current Polish building standards containing daylight recommendations do not precisely indicate what actions are required to provide good daylight design and what kind of daylight metrics are needed to achieve a better quality of daylight. The research results suggest that daylight design guidebooks explaining how to effectively plan for a daylight environment are essential. National standards for daylighting are needed. The results of the pilot questionnaire show a lack of daylight training among future architects and urban specialists. Therefore, new educational channels should be created to propagate the use of daylight design methods and techniques amongst those professionals engaged in urban planning processes.

References

• Ander, G., D. FAIA, 2012. FAIA, 2012. Daylighting. Updated by U.S. Department of Energy Federal Energy Management Program (FEMP), Available at: www.wbdg.org/resources/daylighting.php [Accessed 20 July 2015].
• Bartnicka, M. 2013. Zapomniane wzorce, wypaczone idee. Nowatorstwo przełomu lat 20. i 30. XX w. – co po nim zostało? (Forgotten rules, distorted ideas. The remaining legacy of the innovative late 1920s and early 1930s), Architectus, 1 (33).
• Bartnicka, M. 2010. Wczoraj, dziś i jutro w promienach słonecznych (Yesterday, today and tomorrow in daylight), Czasopismo Techniczne Politechniki Krakowskiej Architektura z. 15/2010.
• Building Performance Institute Europe, 2015. Indoor air quality, thermal comfort and daylight. Analysis of residential building regulations in eight EU member states. BPIE March 2015, Available: bpie.eu/indoor.html [Accessed on 29 July 2015].
• Biuletyn Informacji Publicznej, 2010. Główne problemy, cele i kierunki programu wspierania rozwoju budownictwa mieszkaniowego do 2020 roku,
• Curtis, G. E. 1992. ed. Poland: A Country Study. Washington: GPO for the Library of Congress, US, Available at: http://countrystudies.us/poland/ [Accessed on 29 July 2015].
• Compagnon, R. 2004. Solar and daylight availability in the urban fabric, Energy and Buildings 36, pp:321–328.
• DeKay, M., 2010. Daylighting and urban form: an urban fabric of light, Journal of Architectural and Planning Research, 27:1.
• Eurostat, 2015. Housing statistics. Available at: http://ec.europa.eu/eurostat/statistics-explained/index.php/Housing [Accessed on 29 July 2015].
• Grzonkowski, J., 1999. Optymalne wykorzystanie światła dziennego w oświetleniu wnętrz. Bezpieczeństwo Pracy nauka i technika.9/1999, pp.18-20.
• Kierzenkowski, R. 2008. Bridging the Housing Gap in Poland, OECD Economics Department Working Papers, No. 639, OECD 2008. Publishing. Available at: http://dx.doi.org/10.1787/236314440147 [Accessed on 31 July 2015].
• Le Corbusier, C.E. (1931. Vers une architecture) 1989. Towards a new architecture. Translation by F. Etchells. Oxford: Butterworth Architecture.
• Littlefair, P., 2001. Daylight, sunlight and solar gain in the urban environment. Solar Energy Vol. 70, No. 3, pp: 177–185.
• RIBA, 2011. The Case for Space: the size of England’s new homes. Royal Institute of British Architects, London and HomeWise, Available at: http://www.withoutspaceandlight.com [Accessed on 29 July 2015].
• Rybka, A. The Problem and Needs of Existing Urban Multifamily Building Estates in Poland. SSP – Journal of Civil Engineering Vol. 7, Issue 1, 2012; 61-70.
• Tregenza, P., Wilson, M., 2011. Daylighting: Architecture and Lighting Design, Routledge.
• Turlej, Z., 2012. Narzędzia projektowania światła dziennego w budynkach. Prace Instytutu Elektortechniki, zeszyt 256, PW, Warszawa.
• Werner W. A., Jaworski T., Wężyk E., 2007. Realizacja polityki mieszkaniowej Państwa w zakresie budownictwa mieszkaniowego, IRM, Kraków. Wojtkun, G., 2012. Standardy współczesnego mieszklanictwa [Standards of Contemporary Housing], Przestrzeń i Forma, nr 17.

Visual Comfort: Contrast Glare and Sensitivity

by Peter Hansen, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland

The use of daylight as a resource in buildings is an important issue. Although numerous visual comfort models have been developed, they only partially explains the occupants’ perception of visual comfort especially regarding daylighting control, and embed significant uncertainties in their ability to actually predict the borderline between comfort and discomfort.

A newly started PhD study aims to investigate the influence of contrast glare on visual comfort. As existing daylight glare prediction models only consider the impact of large or high intensity glare sources, this study will investigate the influence of contrasts between the task-area and a bright intermediate background; e.g. between a computer screen and the sky seen through a window.

The starting point of the study is an evaluation of existing datasets containing subjective user response data and luminance distributions measurements. The evaluation will focus on studying the contrast between task and background and determine the main influence factors. One task is to improve the glare source detection algorithm that has been implemented in the glare evaluation tool evalglare.

Another objective is to investigate the characteristics that govern the human visual system in relation to glare. Individual differences between subjects are not taken into account in the existing glare models. Up to now eye colour, age and gender have been investigated, but have shown to have little or no impact. This could be an indication that another attribute has an impact on glare perception, such as contrast sensitivity or improperly corrected eyesight.

Based on experimental findings in office-like test rooms, stemming from studies performed with and without daylight, it is expected to improve on current glare prediction models.

A validation process will be undertaken in the form of a post occupancy evaluation in real used spaces.

Dynamic visual comfort in buildings: development of an assessment method based on luminance contrast ratios, applicable to classrooms

by Raquel Viula, Delft University of Technology, The Netherlands

It has now been accepted by most of the lighting research community that spatial- and temporal-based metrics are needed to describe and evaluate the dynamic nature of daylighting performance of buildings. Multiple studies have now been conducted to review and compare existing luminance- and illuminance-based metrics and criteria, identifying their strengths and shortcomings and in some cases proposing new ones. Some of the new knowledge gathered regarding dynamic daylighting performance of buildings and metrics has been integrated in the latest reviews of the IES Lighting Handbook, of the EN 12464-1 and to some extent in LEED v4.

However, there is still no standard accepted method to access visual comfort in daylit buildings and there are major reservations regarding the robustness of the current metrics, the performance criteria to use, and the definition of the calculation methods.

As visual comfort depends on the light that we “see”, generally measured as luminance, there are reasons to believe that luminance metrics can outperform the most commonly used illuminance-based ones for the assessment of visual comfort. In this project, I will be reviewing the existing luminance metrics and in particular existing guidance relating to luminance contrast ratios to find if these could be developed into a reliable visual comfort assessment method.

As expectations regarding the daylighting quality can be space-use related and visual comfort is certainly task-type dependent, it was found appropriate to focus the research in a particular building type and set of activities. Successful daylighting of school buildings has been demonstrated to result in significant energy savings and increased occupant’s comfort and productivity. For that reason, its was considered appropriate to use a set of classrooms as case studies for the development of this method.

The research will be split in two sets of experiments. One set of experiments will be conducted to characterise the dynamic luminous environment of classrooms, a work that will combine actual space measurements and simulation. The other set of experiments will gather occupant’s response to luminance contrast.

The luminance contrast ratio guidelines and the database of luminance measurements resulting from the two sets of experiments will be brought together into a dynamic visual comfort assessment method applicable to classrooms.

Dynamic perceptual effects of daylight in architectural space

by Siobhan Rockcastle, Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland

Humans perceive daylight as a rich and dynamic luminous composition and yet existing performance metrics most often evaluate natural illumination for its ability to adequately illuminate a two-dimensional task surface while avoiding glare-based visual discomfort. This rather limited task-driven approach places a disproportionate emphasis on surface illumination and glare-based discomfort. While metrics based on surface Illuminance are abstract measurements that we never actually perceive from a human point-of-view, Glare-based metrics assume comfort satisfaction to be the lack of excessively high contrast ratios in the field of view – in other words, a lack of ‘discomfort.’ These metrics ignore the likelihood that contrast and composition provide a positive visual impact on our dynamic perception of architectural space. Existing studies on perceptual daylight performance have linked factors such as contrast and luminous diversity to user preference ratings, yet they have mostly relied on global photometric measures. While some studies have found that both mean luminance and luminance variation within an office environment contribute to occupant impressions of preference (Cetegen, et al., 2008) (Newsham, et al., 2005) (Newsham, et al., 2010), others have discovered that the distribution of luminance values across an occupant’s field-of-view (Boubekri, et al., 1991) (Tiller & Veitch, 1995) as well as the strength of variation are factors of preference (Wymelenberg & Inanici, 2009) (Parpairi, et al., 2002). While these global contrast measures provide a single comprehensible value, they cannot effectively predict perceived contrast between two images that vary in composition (Simone, et al., 2012). To overcome this limitation, more sophisticated contrast measures have been developed in the fields of image analysis and vision research. The current state of the art in these fields would define two main types of measures that are commonly used to quantify contrast: those that rely on global measures (such as Michelson and RMS) and those that rely on local measures. Local contrast measures were developed to overcome the limitations associated with global measures by quantifying the effect of composition on contrasting areas of brightness and darkness. Most promising within this group of measures, are methods that calculate the difference between a single pixel and a surrounding region or neighborhood (Tadmor & Tolhurst, 2000) (Rizzi, et al., 2004) (Matekovic, et al., 2005). This PhD will evaluate a comprehensive range of luminance-based measures for contrast and spatial diversity in simulated HDR renderings of contemporary architecture to validate their use in measuring contrast under variable daylight conditions. To build a more robust metric for predicting contrast-based visual effects from an occupant perspective, this PhD seeks to validate these measures through a survey-based experimental study. To compare existing contrast metrics to subjective human assessments, the authors modelled a range of contemporary architectural spaces, which were selected based on the daylight composition of a prominent interior view and which cover a gradient of contrast-based visual effects. In the proposed method, the authors have chosen a repetitive and clustered 3 x 3 Latin-square design of experiments, which allows for the comparison of three variables – spaces, subjects, and solar position – while limiting subject fatigue resulting from a full factorial experimental approach. While the experiment is intended to study the effects of architectural composition and sun position on a subject’s impression of contrast and composition, there is a risk that the architecture may bias subjective assessments of daylight composition under multiple sun positions. To overcome this, a latin-square design of experiments allows us to create three subject groups – each of which sees a single rendering of each of the nine spaces, but with a different sun position in each space (Figure 1). With three distinct groups, we can then compare the effect of architectural composition within groups and sun position between groups. These subjective assessments can then be compared to quantitative measures to find which, if any, metrics can best predict user impressions.

Figure 1 Shows the 9 Architectural Spaces selected for the study and the 3 renderings per space, which represent maximum, minimum, and average levels of RAMMG contrast over 28 symmetrical semi-annual instances under sunny sky conditions.

References

• Boubekri, M., Hull, R. & Boyce, L., 1991. Impact of Window Size and Sunlight Penetration on Office Worker’s Mood & Satisfaction: A Novel Way of Assessing Sunlight. Environment & Behavior, 23(4), pp. 474-493.
• Cetegen, D., Veitch, J. & Newsham, G., 2008. View Size and Office Illuminance Effects on Employee Satisfaction. Ljubljana, Slovenia, s.n., pp. 243-252.
• Flynn, J., Hendrick, C., Spencer, T. & Martyniuk, O., 1979. A guide to methodology procedures for measuring subjective impressions in lighting. Journal of IES, pp. 95-110.
• Hess, R., Bradley, A. & Piotrowski, L., 1983. Contrast-coding in amblyopia. I. Differences in the neural basis of human amblyopia. London, s.n., pp. 309-330.
• Loe, D., Mansfield, K. & Rowlands, E., 1994. Appearance of Lit Environment and its Relevance in Lighting Design: Experimental Study. Lighting Research and Technology Vol 26, pp. 119-133.
• Matekovic, K. et al., 2005. Global Contrast Factor: a New Approach to Image Contrast. Aire-la-ville, Computational Aesthetics in Graphics, Visualizationg, and Imaging.
• Newsham, G., Cetegen, D., Veitch, J. & Whitehead, L., 2010. Comparing Lighting Quality Evaluations of Real Scenes with those from High Dynamic Range and Conventional Images. Transactions on Applied Perception.
• Newsham, G., Richardson, C., Blanchet, C. & Veitch, J., 2005. Lighting quality research using rendered images of offices. Lighting Res. Technol., pp. 93-115.
• Parpairi, K., Baker, N., Steemers, K. & Compagnon, R., 2002. The Luminance Differences index: a new indicator of user preferences in daylit spaces. Lighting Research and Technology Vol 34 (1), pp. 53-68.
• Rizzi, A., Algeri, G., Medeghini, D. & Marini, A., 2004. A proposal for contrast measure in digital images. Aachen, s.n.
• Simone, G., Pedersen, M. & Hardeberg, J. Y., 2012. Measuring perceptual contrast in digital images. J. Vis. Commun. Image R., pp. 491-506.
• Tadmor, Y. & Tolhurst, D., 2000. Calculating the contrasts that retinal ganglion cells and LGN neurones encounter in natural scenes. Vision Research 40, pp. 3145-3157.
• Tiller, D. & Veitch, J., 1995. Perceived Room Brightness: Pilot Study on the Effect of Luminance Distribution. Lighting Research and Technology Vol 27 (2), pp. 93-101.
• Tremeau, A., 2000. Color contrast parameters for analysing image differences. Derby, s.n., pp. 11-23.
• Veitch, J. & Newsham, G., 2000. Preferred Luminous Conditions in Open Plan Offices: Research amd Practice Recommendations. Lighting Research and Technology Vol 32, pp. 199-212.
• Wymelenberg, K. & Inanici, M., 2009. A Study of Luminance Distribution Patterns and Occupant Preference in Daylit Offices. Quebec City, s.n.

Local solutions for global energy reduction in healthcare design

by Thorsten Lang, University of Ferrara, Italy

Hospitals are responsible for very significant energy consumption. A reduction of consumption by 50% is proposed by the Streamer project under the seventh framework programme (call EeB.NMP.2013-5). The target while easily attainable for new buildings, will have to be met by dealing with existing buildings by means of conversions and retrofitting. Hospitals in four nations will implement proposals within 2017.

Most energy is used by the combination of mechanical ventilation with air conditioning together accounting for nearly half of energy consumption. Based on collected data, the largest energy savings are to be expected from shutting down of the functional areas or buildings not in use. Applied to a hospital wing that is not in use, all building services (electricity and ventilation) may be shut down temporarily except those that monitor hazards or prevent overheating. In order to do so spaces will have to be grouped by period of usage. This can be achieved by rearranging the plan layout, a top down approach studied by the research group, which however falls outside of the reduced scope of the following research.

Consumption of hospitals between north and south Europe is found to be similar, one impacted more by heating, the other by cooling. Both are on the opposite side of the same scale. Each single space will heat up or cool down based on its heat balance. The sum of heat gains and losses for each space, related to outside temperature through the facade. Increasing performance of building shells with better insulation and low emission double glazing better contain heat within the building. Thus it lowers the outside temperature at which overheating may occur. It is thus increasingly likely that buildings overheat even in moderate climates and even in cooler seasons. Daylight and sun control therefore require a separate study following a bottom up approach.

To reduce centralized ventilation local solutions are studied that improve use of daylight, maintain views, allow natural ventilation and avoid overheating. Using a software combining daylight and energy simulation, for a number of differently oriented spaces in the sample hospitals existing thermal will be modeled, internal heating loads can be used as an input, different scenarios for improving the facade performance or reducing loads from energy efficient light can be simulated. Based on the heat load and facade performance the desired shading period will be more or less extensive.

Possible outcomes can be retrofitting solutions containing facade improvements, a fixed or mobile shading system, and classification of the suitability of each space or orientation for functions with a high heat load that may be fed into the IFC model and used to influence studies improving the layout.

Behavioural Impact of Daylight: Does it Influence Seat Choice in an Open-Plan, Hot-Desk Work Space?

by Zeynep Keskin, The University of Sheffield, UK

From its early stages of conception and development, daylight should dictate the quality of the architectural space, ultimately leading to a visual environment which is healthy, inspiring and stimulating for the occupants. In order to use the potential benefits and attributes of daylight in design practice, a set of daylight performance metrics have been developed. While these metrics predict the physically available amount of daylight in a building, field studies are necessary to understand how people tend to respond to changing indoor illuminance distributions. This study seeks to investigate the extent to which the influence of daylight on behaviour can be predicted, and for this the behaviour investigated is seating preferences of occupants in an open plan, hot-desking space in a university library. This was studied for two separate two-week periods, summer and autumn, when daylight and student attendance would vary; the aim was to determine patterns of space occupancy in relation to current daylight performance metrics. The influence of other factors on seat choice such as privacy, location of power sockets, view and noise is being examined in further work.

Research Questions
1) Does a significant relationship exist between occupant’s seating preference and daylight availability?
2) Can this be predicted with current daylight performance metrics such as daylight factor, useful daylight illuminance or daylight autonomy?

Objectives
1) to establish metrics for assessing space utilization (the proportion of time that the seat is used compared to its availability, or the number of people utilised desk area)
2) to identify and implement daylight performance metrics for measuring daylight availability
3) to find the most appropriate metric for measuring each attribute, i.e. space utilization and daylight availability
4) to compare the occupancy evaluations to the simulated daylight availability values

Methodology
The methodology implemented in this research was divided into two successive stages. First, field work observations were performed to understand how people tend to respond to changing illuminance distributions, i.e. where they prefer to sit in the room. The occupant behaviour is based on seating preferences, and it is calculated using the standard formula for space utilization adopted from the National Audit Office (NAO), as summarized below;

space utilization = (frequency rate x occupancy rate)/100 (Equation 1)

where

• frequency rate (%) = the proportion of observation points at which an observation zone was occupied by at least one person.
• occupancy rate (%) = the proportion of total capacity that was occupied, where total capacity is number of seats in an observation zone multiplied by the number of observation points.
• space utilization (%) = the product of frequency rate (%) and occupancy rate (%).

The second step of the research involves performing a daylighting analysis through simulation. The simulations were performed using DAYSIM within Autodesk Ecotect Analysis in order to predict the physically available amount of daylight in the room. Daylight was analysed using three metrics; (i) daylight factor, (ii) useful daylight illuminance, and (iii) daylight autonomy. The aim was to compare measures of daylight availability with measures of space usage, this being a proxy for occupancy behaviour.