Research Archives - RecoD

Daylighting

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Daylighting for Visual Comfort and Energy Conservation in Offices

Kaftan’s Ph.D. Dissertation (First Part)
Author: Dr. Eran Kaftan, Advisor: Prof. Evyatar Erell

Ben-Gurion University of the Negev, Department of Man in the Desert, October 2012

Abstract

D1_Design-Problem

Design Problem: extensive glass facades, a popular architectural feature, create a very problematic visual conditions due to glare (left) or façade covered by curtains, with no use of daylight but merely artificial lights (right).

The use of large glass facades, currently a popular architectural feature, does not ensure better use of daylight, as is often suggested, and in fact may create glare hazards. As a result, we often see windows that are permanently covered by closed blinds or opaque curtains, with electric lights switched on even during the daytime.


Methodological Problem: research in architectural practice encounters difficulties since most daylighting research methodologies and tools designed for academia. However, the academic research process is fundamentally different from processes in architectural practice.

Methodological Problem: research in architectural practice encounters difficulties since most daylighting research methodologies and tools designed for academia. However, the academic research process is fundamentally different from processes in architectural practice.

The research consists of two parts: first, a study of daylighting in offices in sunny locations, which was used to draw mainly prescriptive and performance recommendations, as well as to serve as a case study for a research process. From the architect’s point of view, both performance and prescriptive recommendations are somewhat limited, since they do not teach how to design optimized or unique solutions. Therefore, in addition, the second part of this research consists of the development of methodological recommendations for the integration of daylighting research during the architectural design process.


Glare Analysis Methodology: measurements and analysis of glare were carried out by using High Dynamic Range Photography (Left) to generate Luminance Map (Right).

Glare Analysis Methodology: measurements and analysis of glare were carried out by using High Dynamic Range Photography (Left) to generate Luminance Map (Right).

The first part of the research included a field survey of offices and a controlled experiment on daylighting. The field survey was carried out to identify some of the causes for extensive use of artificial lights in Israeli offices, where substantial energy saving may be achieved through the use of daylight; and to examine various survey techniques.


Field Survey of Offices : luminance map (left) and glare analysis (right) of case study # 015.   The office suffers from problematic visual conditions: when blinds open, glare negatively affect the working environment quality; and when they are closed, the natural illuminance is low, requiring artificial lights. As a side effect, desirable view outside will often be blocked by shading systems due to glare.

Field Survey of Offices: luminance map (left) and glare analysis (right) of case study # 015.
The office suffers from problematic visual conditions: when blinds open, glare negatively affect the working environment quality; and when they are closed, the natural illuminance is low, requiring artificial lights. As a side effect, desirable view outside will often be blocked by shading systems due to glare.

The survey confirmed that offices often suffer from problematic visual conditions: When blinds or curtains are open, glare may affect the quality of the working environment negatively; and when they are closed, the result is often low natural illuminance, forcing the occupants to use artificial lights.


A Controlled Experiment on Daylighting: a statistical survey of visual comfort in a controlled office environment; including objective measurements (left) and subjective responses to a questionnaire (middle), carried out simultaneously in two identical rooms (right).

A Controlled Experiment on Daylighting: a statistical survey of visual comfort in a controlled office environment; including objective measurements (left) and subjective responses to a questionnaire (middle), carried out simultaneously in two identical rooms (right).

The controlled experiment was carried out to evaluate the effectiveness of several daylighting systems and office layouts with regard to visual comfort and energy conservation in sunny regions, and to evaluate the predictive power of several glare indices. The survey, which included 59 subjects, was carried out in a daylit environment set up to simulate a typical office. Visual comfort was evaluated based on both objective measurements and subjective responses to a questionnaire.


Selected Results -- A light shelf: A light shelf located between upper daylight windows and lower view windows, with blinds closed when low solar, was found as good means for providing sufficient natural illuminance without glare.

Selected Results — A light shelf: A light shelf located between upper daylight windows and lower view windows, with blinds closed when low solar, was found as good means for providing sufficient natural illuminance without glare.

Overall, the experiment showed that the effect of tinted glazing and desk position on visual comfort was quite modest. The effect of blinds on visual comfort was positive (although blinds require frequent adjustment, which is rarely done in practice). A light shelf with blinds deployed below it may provide high quality daylight: it reduces glare in a working area near the window while enabling higher illuminance levels deeper in the office. Subjects were happy with relatively high levels of horizontal illuminance at their desk, well above the minimum recommended in ISO Standard 8995 for the illumination of work spaces.


Selected Results -- Validation of Glare Indices for Sunny Regions: A clear relationship identified between measurements and the subjects’ assessment of glare, enables safer use of these indices for daylighting design and research in sunny regions.

Selected Results — Validation of Glare Indices for Sunny Regions: A clear relationship identified between measurements and the subjects’ assessment of glare, enables safer use of these indices for daylighting design and research in sunny regions.

While the glare indices DGI, UGR, CGI, and VCP may differentiate between glare and non-glare conditions, they are less effective in distinguishing between various levels of glare in brightly lit offices. In contrast, the Daylight Glare Probability (DGP) index, which was designed specifically for daylit environments (but which is based on a survey conducted in Germany and Denmark, countries with relatively overcast skies, and while using Venetian blinds most of the time) was shown to be effective in Israel, too.


A Fundamental Daylight Solutions: a part of recommendations (in Hebrew) for better design of daylighting in sunny regions, available at  http://www.bgu.ac.il/CDAUP/daylighting-guidelines-hebrew.pdf (Prof. Evyatar Erell & Dr. Eran Kaftan. 2011. The Israeli Ministry of National Infrastructures. 50p.).

A Fundamental Daylight Solutions: a part of recommendations (in Hebrew) for better design of daylighting in sunny regions, available at http://www.bgu.ac.il/CDAUP/daylighting-guidelines-hebrew.pdf (Prof. Evyatar Erell & Dr. Eran Kaftan. 2011. The Israeli Ministry of National Infrastructures. 50p.).

Finally, conclusions from both investigations were used to generate local recommendations: guidelines for architects, submitted to the Israeli Ministry of National Infrastructures; and a proposal for a revision of the daylight section of the Israel Green Building Standard (Standard 5281).


Relevant Publications

Kaftan, Eran. 2012. Daylighting for Visual Comfort and Energy Conservation in Offices and the Development of Methodologies for Research in Architectural Practice. A Ph.D. Dissertation. Ben-GurionUniversity of the Negev, Israel.

Erell Evyatar, & Kaftan, Eran. 2011. Daylighting for Visual Comfort and Energy Conservation in Offices in Sunny Locations. A Research Report. Ministry of National Infrastructures, Israel.

Erell Evyatar, & Kaftan, Eran. 2011. Daylighting for Visual Comfort and Energy Conservation in Offices in Sunny Locations: Guidelines for Designers. Ministry of National Infrastructures, Israel.

Project of the Year 2012, in Research Category: the Emilio Ambasz Award for Green Architecture. “Positioning Workstations in Sunny Areas”. Published in Architecture of Israel (Architectural Quarterly). No. 91, pp 65 & 68. 2012.

Erell, Evyatar & Kaftan, Eran & Garb, Yaakov. (2014). Daylighting for Visual Comfort and Energy Conservation in Offices in Sunny Regions. Conference: 30th PLEA International Conference – Sustainable Habitat for Developing SocietiesAt: Ahmedabad, India.

Kaftan, Eran, 2015. The Science & Art of Daylighting Design. Electricity & People: periodical of  the Society of Electrical and Electronics Engineers in Israel. No. 56. P 50.

Wienold, J., Iwata, T., Sarey Khanie, M., Erell, E., Kaftan, E., Rodriguez, R., … Andersen, M. (2019). Cross-validation and robustness of daylight glare metrics. Lighting Research & Technology, 51(7), 983–1013. The paper received the Leon Gaster Award from the Society of Light and Lighting (CISBE).

Geraldine Quek, Jan Wienold, Mandana Sarey Khanie, Evyatar Erell, Eran Kaftan, Athanasios Tzempelikos, Iason Konstantzos, Jens Christoffersen, Tilmann Kuhn, Marilyne Andersen. 2021. Comparing performance of discomfort glare metrics in high and low adaptation levelsBuilding and Environment, Volume 206, 2021.


Practical Research

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Development of Methodologies for Research in Architectural Practice

Kaftan’s Ph.D. Dissertation (Second Part)
Author: Dr. Eran Kaftan, Advisor: Prof. Evyatar Erell

Ben-Gurion University of the Negev, Department of Man in the Desert, October 2012

Abstract

Proposed Model of Design Process, Expert Knowledge, & Practical-Research: relationships among architectural design, expert knowledge, and practical-research (in plan view).

Proposed Model of Design Process, Expert Knowledge, & Practical-Research: relationships among architectural design, expert knowledge, and practical-research (in plan view).

 

The  research (second part of Ph.D.) included meta-analysis (of the first part), syntheses (with several aspects of daylighting practice), and the development of a workflow for daylighting design and research in architectural practice.

The meta-analysis included additional investigations (beyond the conventional methodology presented in the first part of this research), in particular analysis for revealing tacit information and a study of the suitability of the academic research process for research in architectural practice. It was found that the key research steps are similar. However, although the steps occur in the same order, there is a considerable difference between the two realms (academic and practice), especially regarding the objectives and scope of most steps.


Proposed Model of Design Process, Expert Knowledge, & Practical-Research: integrated expert knowledge and practical-research within a design process (for a single expertise, such as daylighting; in section view).

Proposed Model of Design Process, Expert Knowledge, & Practical-Research: integrated expert knowledge and practical-research within a design process (for a single expertise, such as daylighting; in section view).

 

The syntheses were designed to bridge the knowledge gap between the focused knowledge acquired through the first part of the research and the comprehensive knowledge required for the development of the second part. They consisted of first expanding the literature review to various fields, which the research sub-problems interface. This information was then merged with the focused knowledge acquired through the fundamental daylight research and its meta-analysis, to develop methodological recommendations.

These methods were organized in a single, comprehensive daylighting workflow. The workflow proposes a better integration of research in the design process, by utilizing a comprehensive approach to organize the relevant tasks required for effective design of daylighting. This is done according to the required expertise (architectural design, daylighting consultation, and practical-research) and according to the major design phases (and sub-steps).


The proposed workflow further proposes, in detail, a process for carrying out research on daylighting in architectural practice, using scientific tools (mainly daylight simulations). Such research is a modified version of academic or applied research methodologies, designed to accommodate the nature of the architectural practice as well. However, since its scope and objectives are substantially different from those of an academic or applied research, the term Practical-Research was proposed for such an investigation. The design process may accommodate several practical-research studies, each of a short duration.

Proposed Daylighting Workflow: an outline of design and practical-research methods for architectural practice.  The proposed Practical-Research is a systematic inquiry designed to generate missing information to the design team. It usually includes a very short autonomous process carried out during certain stages of the design process.

Proposed Daylighting Workflow: an outline of design and practical-research methods for architectural practice.
The proposed Practical-Research is a systematic inquiry designed to generate missing information to the design team. It usually includes a very short autonomous process carried out during certain stages of the design process.

 


The workflow may be used to develop an expert system program, helping designers and experts through the processes of daylighting design and research in architectural practice. In addition, the proposed workflow may be applied, with appropriate modifications, to other design fields (such as solar shading, thermal properties, acoustics, and natural ventilation); further supporting the field of performance-oriented architecture.

Relevant Publications

Kaftan, Eran. 2012. Daylighting for Visual Comfort and Energy Conservation in Offices and the Development of Methodologies for Research in Architectural Practice. A Ph.D. Dissertation. Ben-GurionUniversity of the Negev, Israel.

Project of the Year 2013, in Research Category: the Emilio Ambasz Award for Green Architecture. “Practical Research: Integrating Research into Architectural Practice”. Published in Architecture of Israel (Architectural Quarterly). No. 96, p 92. 2014.


Optimal Shading

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The Cellular Method for Optimal Shading

Master Thesis. Author: Eran Kaftan
Committee Members: Chalfoun N. (chair), Yoklic M., Matter F., Medlin L., & Sobin H.
The University of Arizona, College of Architecture, 2001.

Abstract

The cellular method is an innovative approach to design an optimal shading. The method offers calculating an optimal shading form, accounting for both needs of summer solar protection and winter solar gain. As a result, it provides better thermal comfort and maximum annual energy conservation in cooling and heating. The method can generate Mapping of Shading Importance for any location in the world, any opening configurations, and any preferred period (such as year, season, month, etc.). The mapping indicates, for these particular settings, the optimal form of shading-means (such as shading device, overhang, etc.). Since architectural and environmental settings are varied, the calculated optimal shading forms usually have unique forms, often complex and intriguing. Such forms are not only enriching the building façade, but also correspond best to the specific environmental conditions.

The method was developed by architect Dr. Eran Kaftan, in the framework of a M.Arch thesis at the University of Arizona (2001). It was presented at several international conferences and at leading international architectural and engineering offices, such as Frank Gehry & Associates; ARUP; and Foster and Partners. In addition, it was integrated in several simulation programs, Autodesk Ecotect and SHADERADE of Harvard University.

Optimal-Shaing_N

Optimal Shading

The design of shading-means which provides optimal shading (establishing maximum reduction in the building energy consumption) is rather complex, requiring solving the fundamental “Shading Dilemma”. On the one hand, shading intercepts summer direct solar radiation, thus, reducing the cooling loads during the summer (positive effect); however, on the other hand, shading also reduces desirable winter solar gain and daylight, thus, increasing the heating and artificial lighting loads (negative effect). Therefore, an optimal form of a shading device or overhang should provide an optimal balance among the necessity for solar obstruction, solar gain, and daylight. Since solar radiation varies according to different sun angles, and the sun appears in the sky in curved pathways, even a rectangular window will not have a simple optimal shading form. In addition, since windows or walls are varied in configurations, orientations, and locations around the world, it is natural, that each one requires a unique shading form. An optimal shading form can help in optimizing annual building energy conservation, reducing the cost in operating mechanical systems of cooling and heating; thus supporting the world energy conservation and sustainability.

The Cellular Method

The Cellular Method for Optimal Shading evaluates numerous theoretical-cells of proposed shading-means (such as shading device, overhang, etc.) for their degree of importance to provide shade or solar penetration. Then, this information can be utilized to modify the proposed shading-means. The method can also be used to determine new shading-means, by evaluating numerous theoretical-cells of space adjacent to a proposed shaded space (such as window, courtyard, etc.). Calculations of the optimal shading form takes into consideration the window configuration, orientation, and geographical location, as well as hourly solar radiation and hourly thermal comfort conditions at the space needed to be shaded. This process can be applied to a particular preferred period, in order to design fixed or seasonal shading-means (such as shading devices, overhangs, shading membranes, etc). In addition, it can be applied to a sequence of short time-segments, in order to design dynamic shading systems.

OS_Cellular-Shading-Approch

 

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Applications

[reduced width] The Cellular Method for Optimal Shading was implemented in several state-of-the-art simulation programs. [/reduced width]

RecoD_Optimal-Shading-Tool

Excel Tool (2001)

An excel tool, OPTIMAL-SHADING, uses the Cellular Method for Optimal Shading, through about 800,000 calculations, to determine the optimal shape of shading-means. The tool is limited to simple forms of windows, and requires an external thermal analysis.


Ecotect’s Cellular Method Plugin (2005)

Collaboration between Research & EcoDesign and Ecotect developer (SQUARE ONE research) has produced an external Plug-In for Ecotect software. The plug-in uses the Cellular Method for Optimal Shading to determine for outdoor locations the degree of importance to provide either shading or solar penetration during a period. The process is carried out in the following steps:

1. Setting a shading grid;

1. Setting a shading grid;

2.Calculating annual solar potential (solar radiation admitted or eliminated through selected windows);

2. Calculating annual solar potential (solar radiation admitted or eliminated through selected windows);

3. Calculating annual shading needs (the requirements for either shading or solar gain, according to thermal comfort,  zone temperatures, or  heat gain and losses);

3. Calculating annual shading needs (the requirements for either shading or solar gain, according to thermal comfort, zone temperatures, or heat gain and losses);

4. Conducting hourly shading projection and a data accumulation process (at all cells);

4. Conducting hourly shading projection and a data accumulation process (at all cells);

5. Reciving a map of final degrees of importance at different regions of a proposed shading; device, to provide either solar shading (blue scale) or solar penetration (red scale) during a period (such as the entire year);

5. Reciving a map of final degrees of importance at different regions of a proposed shading; device, to provide either solar shading (blue scale) or solar penetration (red scale) during a period (such as the entire year);

6. Optimizing the shading form acording to the shading importance map.

6. Optimizing the shading form acording to the shading importance map.

Ecotect-Shading-PotentialAutodesk Ecotect (2008)

Another result of the collaboration with Ecotect developer is that major parts of the Cellular Method for Optimal Shading can be used directly within the Autodesk Ecotect software. The tool can be launched through a “shading potential” calculation option. The tool calculates the relevant accumulation of radiation data on an analysis grid for a selected period, but in contrast to the plug-in, it does do not account for both summer needs for shading and winter needs for solar penetration. Additional information may be found in Ecotect’s help files.


Harvard-SHADERADESHADERADE (Harvard University; 2011)

The tool uses a modified version of the Cellular Method for Optimal Shading to generate optimal shading using Rhinoceros® and EnergyPlus programs (it is scheduled to be released as an addition to the DIVA-for-Rhino plug-in).


Relevant Publications

Kaftan, Eran. (2001). The Cellular Method to Design Energy Efficient Shading Form to Accommodate the Dynamic Characteristics of Climate. Master Thesis (Architecture). The University of Arizona. 183p.

Kaftan, E. (2001). The Cellular Method to Design Energy Efficient Shading Form to Accommodate the Dynamic Characteristics of Climate. Conference proceedings. PLEA 2001 – The 18th Conference on Passive and Low Energy Architecture. Florianopolis, Brazil. Volume 2. pp 829-833.

Kaftan, E. (2002). Cellular Method for Optimal Solar Shading. US Patent Application. 46p.

Kaftan E. & Marsh A. (2005). Integrating the Cellular Method for Shading Design with a Thermal Simulation. The International Conference on Passive and Low Energy Cooling for the Build Environment (PALENC 2005), Santorini, Greece.

Kaftan, E. and Ben-Aharon R. (2005). Passive – Yet Not Indifferent: Cellular Shading Method. Architecture of Israel (Architectural Quarterly). No. 62, pp 51-55.

Sargent, Jon, Niemasz Jeffrey, & ReinhartChristophF. (2011). SHADERADE: combining rhinoceros and energyplus for the design of static exterior shading devices. Building Simulation 2011. Sydney, Australia.

Kaftan Eran, 2015. Urban Shade: Thermal and Visual Experience. Urban Shading In Israel. Editor: Martin Weyl. Israel.

Natural Flow Pattern

 


The Natural Flow Pattern

Kaftan’s B.Arch Research
Author: Eran Kaftan

The University of Arizona, Architectural Department, 2000

Abstract

 

Observation of the natural flow pattern that water creates in the natural landscape can aid the organization of the pedestrian environment by applying its principles to improve the flow of pedestrian circulation.  We can find some resemblance between pedestrian circulation and fluid movement (1) because they are driven by the same kinetic force.  People, like water, move in a flowing motion. Once they accelerate, they are directed by momentum. Consequently, every bend is smoothly curved, creating equilibrium between the rectilinear momentum force and the individual’s desire to turn. This creates an optimal flow pattern whose paths require the least effort (1). We can find evidence of these paths if we carefully examine the way people move around street corners.  Instead of a square turn, as we would expect, we would detect that their course follows a sharp curve.  Many of the natural flow characteristics can be utilized architecturally in different scales, from the curved line and the meandering shape to a larger scale where we can find similarities between the watershed basin and a city with its neighborhood.

 

 

0_Intro

 

02_Features-W

 

Selected Features

1_Hierarchic-Order

2_Curved-line

3_Meandering-shape

4_Island-Formation

5_Whirling-Movment

6_Radial-flow-pattern

7_Continuous-Movment

8_Flowing-and-Convergence

9_Conclusion

10_Ref

Flow-References

Relevant Publications

Presented at: Expo on Line: THE CITY: THIRD MILLENNIUM, International Competition of Ideas Architecture Biennale, 2000, Venice. International Architecture Exhibition, The City: Less Aesthetics, More Ethics.

Examples for Architectural Implementation

Proposal for Civano Master Plan, Tucson, USA, Arch. Eran kaftan, 1999 (Selected View)

Proposal for Civano Master Plan, Tucson, USA, Arch. Eran kaftan, 1999 (Selected View)

Hefer-School-Plan

A Proposal for Hefer School, 2004. Architects: Shooky Shoshany Architects, Avinoam Levin Architects, and Research & EcoDesign. Landscape Planners: Kolan and Ben-Nun

Hefer-School-3d

Hefer School Rendering: Gil Branshteen