A heliodon (HEE-leo-don) is a device for adjusting the angle between a flat surface and a beam of light to match the

angle In Euclidean geometry, an angle can refer to a number of concepts relating to the intersection of two straight Line (geometry), lines at a Point (geometry), point. Formally, an angle is a figure lying in a Euclidean plane, plane formed by two R ...

between a horizontal plane at a specific latitude and the solar beam. Heliodons are used primarily by

architects An architect is a person who plans, designs, and oversees the construction of buildings. To practice architecture means to provide services in connection with the design of buildings and the space within the site surrounding the buildings that h ...

and students of architecture. By placing a model building on the heliodon’s flat surface and making adjustments to the light/surface angle, the investigator can see how the building would look in the three-dimensional solar beam at various dates and times of day.

History

Shortly after

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, in the 1950s, there was a wide interest in producing building design techniques that correspond to the climate. At Princeton Architectural Laboratory, Thermoheliodon was invented by Olgyays in hopes to create physiological conditions of human comfort through

architectural design Building design, also called architectural design, refers to the broadly based architectural, engineering and technical applications to the design of buildings. All building projects require the services of a building designer, typically a licen ...

. Thermoheliodon was a domed insulated evaluation bed for scaled

architectural model An architectural model is a type of scale model made to study aspects of an architectural design or to communicate design intent. They are made using a variety of materials including paper, plaster, plastic, resin, wood, glass, and metal. Mod ...

s in certain climatic conditions measured to a high level of calculation and accuracy. The device was a covered simulating environment where a scaled model’s thermal performance could be evaluated under different temperatures. However, attaining precise evaluation was an issue with Thermoheliodion due to the impact of scale on thermal performance. Although Thermoheliodon failed to produce an accurately measured environment, the device led to further research on adaptive and efficient design orientation of buildings and developed the base of

bioclimatic Green building (also known as green construction, sustainable building, or eco-friendly building) refers to both a structure and the application of processes that are environmentally responsible and resource-efficient throughout a building's l ...

design principles. During the 1950s, The Building Research Station (BRS), a key institution in the UK designed Heliodon as part of Tropical Architecture and Bio-climatic Architecture. The institution aimed to enhance housing conditions and development of local resources for construction in colonial territories. Heliodon was designed to replicate the sun on architectural scale models through a point of light. The device can shift and tilt to obtain the accurate position of the sun on any given day, time, or location. In the 1960s, a heliodon was invented by Gershon Fruhling in

Israel Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

, recorded by the United States Patent Office. This heliodon consists of a platform created to hold a model of the building whose isolation is to be evaluated. The horizontal platform can sway on a rotatable vertical shaft which can turn on its axis. The rotation allows horal and seasonal adjustments and swings the unit almost to its base. The titling of the shaft enables the adjustment to various geographical locations on the latitude scale. Any external light source along with the sun can be utilised and the placement of this light source can be kept stationary throughout the observations. This heliodon is an accurate instrument that can make rapid and simple adjustments. And the requirement of providing a precisely located light source is not necessary. In the 1990s, modern heliodons with quicker simulations and a greater level of accuracy were invented. EPFL Solar Energy and Building Physics Laboratory LESO-PB in Lausanne designed a robotic heliodon to simulate direct light. This heliodon is combined with a sky scanning simulator (

artificial sky The artificial sky is a daylight simulation device that replicates the light coming from the sky dome. An Architectural model, architectural scale model or 1:1 full-scaled aircraft is placed under an artificial sky to predict daylight penetration w ...

) to predict the light distribution in a building over the entire year. The device can reproduce direct light at any location on Earth. After the 2000s, Prof. Norbert Lechner, an architect, LEED AP and an expert in energy responsive

architecture Architecture is the art and technique of designing and building, as distinguished from the skills associated with construction. It is both the process and the product of sketching, conceiving, planning, designing, and construction, constructi ...

has invented a manual Sun Emulator Heliodon. He invented heliodons which were much easier to evaluate

daylight Daylight is the combination of all direct and indirect sunlight during the daytime. This includes direct sunlight, diffuse sky radiation, and (often) both of these reflected by Earth and terrestrial objects, like landforms and buildings. Sunlig ...

simulation than the previous models. The Sun Emulator Heliodon can precisely show all solar responsive design principles and strategies. Although the device can hold only small architectural scale models, it is a great instrument for teaching solar geometry. This heliodon was manufactured by High Precision Devices and now an alternative device is Orchard Heliodon produced by betanit.com, with the approval of the inventor of the Sun Emulator Heliodon. Since 2004, the Italian company betanit.com is developing various heliodons designed by architect Giulio M. Podesta for use in daylighting laboratories of universities and architectural firms. The architect designed the Orchard Heliodon with similar features to the Sun Emulator heliodon (developed by Norbert Lechner). For more precise simulations, Orange Heliodon, an easy to use robotic heliodon with a fixed light source was designed and was launched in the market in 2007. Moreover, the Orange Heliodon was used at Politecnico di Milano in the architectural design laboratory of the BEST department. It used a computerized and automatic heliodon to reproduce the sunshade. Furthermore, the architect designed Tulip Heliodon, a robotic heliodon with a fixed light source that is often merged with full dome artificial sky for collaborative design and presentation used for

studies. Kwok Pun Cheung, a professor and researcher at the Department of Architecture in Hong Kong University developed various heliodons. Cheung developed a simple tabletop heliodon and multi-lamp heliodon for use in architectural schools. Moreover, a tabletop heliodon with a moving light source was developed for

architect An architect is a person who plans, designs, and oversees the construction of buildings. To practice architecture means to provide services in connection with the design of buildings and the space within the site surrounding the buildings that h ...

offices. A patented portable direct sunlight light-duty universal heliodon set up on a camera tripod was developed for evaluating the impacts of direct sunlight on small

s or building components.

Scientific background

The

Earth Earth is the third planet from the Sun and the only astronomical object known to Planetary habitability, harbor life. This is enabled by Earth being an ocean world, the only one in the Solar System sustaining liquid surface water. Almost all ...

is a ball in space perpetually intercepting a

cylinder A cylinder () has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infinite ...

of parallel energy rays from the Sun. (Think of a tennis ball being held in the wind.) The angle of any site of Earth to the solar beam is determined by *The site’s latitude, which gives its position on the curve of the Earth between the Equator and one of the Poles. *The time of day at the site, measured by its progress eastward around the Earth’s axis from sunrise to sunset. *The date, which locates the Earth on its annual orbit of the Sun. The change due to date is the most difficult to visualize. The Earth’s axis is steady but ''tilted'': the plane that includes the Earth’s

equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...

, which is perpendicular to the axis, is not parallel to the plane that includes the center of the Sun and the center of the Earth, called the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

. Think of the Earth as a car on a Ferris wheel. The car’s axis always points “down”, which changes its relation to the center of the wheel. A light at the center of the wheel would touch the bottom of the car at the top of the orbit and the top of the car at the bottom of the orbit. As the Earth orbits, the location of the centerline of the solar cylinder changes, sliding from the

Tropic of Cancer The Tropic of Cancer, also known as the Northern Tropic, is the Earth's northernmost circle of latitude where the Sun can be seen directly overhead. This occurs on the June solstice, when the Northern Hemisphere is tilted toward the Sun ...

(in June) to the

Tropic of Capricorn The Tropic of Capricorn (or the Southern Tropic) is the circle of latitude that contains the subsolar point at the December (or southern) solstice. It is thus the southernmost latitude where the Sun can be seen directly overhead. It also reach ...

(in December) and back again. This changes sun angles all over Earth according to the date. ''See more at

analemma In astronomy, an analemma (; ) is a diagram showing the position of the Sun in the sky as seen from a fixed location on Earth at the same Solar time#Mean solar time, mean solar time over the course of a year. The change of position is a result ...

.''

Utility

Heliodons can mimic

latitude In geography, latitude is a geographic coordinate system, geographic coordinate that specifies the north-south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from −90° at t ...

, time of day, and date. They must also show a clear north-south direction on their surface in order to orient models. Some heliodons are very elaborate, using tracks in a high ceiling to carry a light across a large studio. Others are very simple, using a sundial as a guide to the adjustments and the sun of the day as a light source. In general, the date adjustment causes the most difficulty for the heliodon designer, while the light source presents the most problems in use. The parallel rays of the sun are not easy to duplicate with an artificial light at a useful scale, while the real sun is no respecter of deadlines or class hours. All heliodons can benefit by including a moveable, tiltable device that can be set to match any surface on a model to show angle of incidence. The angle of incidence device indicates the relative intensity of the direct beam on the surface. The device consists of a diagram of concentric rings around a shadow-casting pointer perpendicular to the diagram. Each ring represents a percent of the direct solar beam incident on the surface. The percentage varies from 100%—the ray runs straight down the pointer perpendicular to the diagram—to zero—the ray runs parallel to the diagram and misses surface. The cosine of the angle of incidence gives the percentage. A cosine of 0.9, 90%, for example, corresponds to an angle of incidence of 26.84 degrees. The radius of the ring for the angle is equal to its tangent times the height of the shadow casting pointer. A 45 degree angle of incidence would generate a cosine of about .7, 70%, for example. Since the tangent of 45 degrees is 1, the radius of the 70% ring would be equal to the height of the shadow-casting rod.

Types of Heliodon

Manual Tabletop Heliodon

Manual Tabletop heliodons are used for sun shading analysis at any given latitude and at any time. The model support platform is mounted on a conventional table or desk. It can rotate and tilt a scaled

. These heliodons are manually operated without the use of computers and provide good accuracy. The model stand, mounted on the table, is tilted for latitude and rotated to get the time of the day. For replicating the time of the year, the single light source uses a ribbon marked with months of the year and attached to the edge of the door. The device can be used in interior spaces with lamps and exterior spaces with direct sunlight for better accuracy. While using outdoors, a sundial controls the tilt and rotation of the model stand. The main advantage is its affordability and small size. The heliodon is accurate when utilized by people who are already aware of solar geometry. But not good for learning solar geometry and the basic principles of solar responsive design. * Department of Architecture at the

University of Hong Kong The University of Hong Kong (HKU) is a public research university in Pokfulam, Hong Kong. It was founded in 1887 as the Hong Kong College of Medicine for Chinese by the London Missionary Society and formally established as the University of ...

uses tabletop heliodon for the solar design of architectural scale models. The heliodon is mainly used for teaching and design purposes.

Manual Sun Emulator Heliodon

The manual heliodon consists of a flat table with a scaled model on top whereas the table lies stationary with only sun lamps in motion. The heliodon consists of a horizontal platform and seven rings that represent the sun path for the 21st day of every month which can be rotated to replicate the time of the day. It acts as a teaching tool for architects, planners, and developers. The heliodon can be used to teach solar geometry and solar responsive design principles in science museums. Without reliance on external sky conditions, it is simple to evaluate sun shading analysis at any latitude. This type of heliodon is very intuitive to adjust and operate. This heliodon requires only limited training since it is easy to understand and operate. Considering the characteristics, the manual sun emulator is also excellent for explaining solar dynamics and cardinal points to children in a function, scientific and fun way of demonstration. Manual sun emulator heliodon is used in various universities such as: *

Auburn University Auburn University (AU or Auburn) is a Public university, public Land-grant university, land-grant research university in Auburn, Alabama, United States. With more than 26,800 undergraduate students, over 6,100 post-graduate students, and a tota ...

Alabama Alabama ( ) is a U.S. state, state in the Southeastern United States, Southeastern and Deep South, Deep Southern regions of the United States. It borders Tennessee to the north, Georgia (U.S. state), Georgia to the east, Florida and the Gu ...

- The university uses a 48” (1.2m) diameter Formica covered sun emulator heliodon known as HPD Model 126 Heliodon. *

Texas Christian University Texas Christian University (TCU) is a private university, private research university in Fort Worth, Texas, United States. It was established in 1873 by brothers Addison Clark, Addison and Randolph Clark as the AddRan Male & Female College. It i ...

Texas Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...

– The students at the university use sun emulator heliodon for daylight studies in lighting design projects. *

Southeastern Louisiana University Southeastern Louisiana University (Southeastern) is a public university in Hammond, Louisiana. It was founded in 1925 by Linus A. Sims as Hammond Junior College. Sims succeeded in getting the campus moved to north Hammond in 1928, when it beca ...

Louisiana Louisiana ( ; ; ) is a state in the Deep South and South Central regions of the United States. It borders Texas to the west, Arkansas to the north, and Mississippi to the east. Of the 50 U.S. states, it ranks 31st in area and 25 ...

– The university uses heliodon as an interactive tool for teaching purposes in designing solar aware

. * Durham School of Engineering and Construction,

Nebraska Nebraska ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Ka ...

– Prof. Norbert Lechner uses sun emulator heliodon to explain sun shading analysis of scale model. * CERES Center at

Ball State University Ball State University (Ball State or BSU) is a public research university in Muncie, Indiana, United States. The university has three off-campus centers in Indianapolis, Fort Wayne, and Fishers, Indiana. The university is composed of seven aca ...

Indiana Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the s ...

* Judson College,

Robotic Heliodon with Fixed Light Source

This type of robotic heliodons is the most accurate sun simulator. It is used to evaluate scale models in a compact space with a fixed light source with the support of a robotic platform. It is an automatically operated heliodon in which a physical model is accurately positioned with the help of computers around two axes. The robotic heliodon can process frequent tests and evaluations on bigger and heavier models than the manual ones to produce precise results for experiments. They are used for daylighting studies in universities, research facilities and development laboratories for sustainable building designs. Some robotic heliodons use a mirror to fold the light path and allow the installation in a small room. The room is normally kept dark without windows and the walls, ceilings and floors are usually in black. Robotic Heliodon is used in architectural schools, research laboratories and large engineering firms such as: * EPFL Solar Energy and Building Physics Laboratory LESO-PB in Lausanne (laboratory-made heliodon) uses a robotic heliodon for the simulation of direct light. This heliodon is combined with a sky scanning simulator (

) to predict the light distribution in a building over the entire year. The tool can replicate direct sunlight at any location on earth. This heliodon is a laboratory-made tool that allows daylighting simulations produced inside scale models for various research and design purposes. The daylighting laboratory manufactured this tool to limit energy savings and increase user comfort through better utilisation of daylighting in buildings. The instrument allows architects, designers, and planners to understand the effect of their architectural concepts. Besides limiting energy consumption, the laboratory focuses to increase the health of building occupants and productivity through efficient use of daylighting. Moreover, the robotic heliodon will help the laboratory’s aim to achieve

energy efficiency Energy efficiency may refer to: * Energy efficiency (physics), the ratio between the useful output and input of an energy conversion process ** Electrical efficiency, useful power output per electrical power consumed ** Mechanical efficiency, a rat ...

and

renewable energy Renewable energy (also called green energy) is energy made from renewable resource, renewable natural resources that are replenished on a human lifetime, human timescale. The most widely used renewable energy types are solar energy, wind pow ...

building A building or edifice is an enclosed Structure#Load-bearing, structure with a roof, walls and window, windows, usually standing permanently in one place, such as a house or factory. Buildings come in a variety of sizes, shapes, and functions, a ...

s and

cities A city is a human settlement of a substantial size. The term "city" has different meanings around the world and in some places the settlement can be very small. Even where the term is limited to larger settlements, there is no universally agree ...

Robotic_Heliodon_with_fixed_light_source

* National Laboratory for Housing and Sustainable Communities at Sonora, Mexico uses Orange heliodon produced by Betanit. The robotic heliodon is used for evaluating solar paths and their interaction with pre-existing or new constructions. By using a scale physical model under the robotic heliodon, it helps the project to measure the comfort and

of the building. The heliodon is efficient as the project considers climatic conditions and the integration of energy sources. As the building is situated in a hot dry climate, the automatic heliodon helped in providing design solutions to offer indirect

natural lighting Nature is an inherent character or constitution, particularly of the ecosphere or the universe as a whole. In this general sense nature refers to the laws, elements and phenomena of the physical world, including life. Although humans are part ...

and ventilation while avoiding direct sunlight into the building’s interior spaces. Due to the accuracy of the robotic heliodon, several studies with photos were used to compare a built house with a solar simulated scale model. The results revealed the efficiency of using appropriate design features in the building, which was derived from automatic heliodon. * Arup (London), an engineering firm uses orange heliodon produced by Betanit in their lighting lab to help simulate the sun for their experiments and buildings. The lighting simulation from the heliodon helps in quickly identifying the

penetration on the buildings. Arup uses the robotic heliodon to design sustainable, energy-efficient, and award-winning concepts in lighting. The engineers and experts analyse daylighting of buildings by replicating the sun for their innovative projects. Furthermore, a thesis project, supervised by Dr Francesco Anselmo, also utilised the heliodon for experimental purposes. The heliodon is also used for curvature and annual reflectivity studies of “Leaf” at Arup in coordination with Betanit.

Robotic Heliodon with Fixed Model

This robotic heliodon is fully automated with a

computer A computer is a machine that can be Computer programming, programmed to automatically Execution (computing), carry out sequences of arithmetic or logical operations (''computation''). Modern digital electronic computers can perform generic set ...

and has lights that go around the fixed scale model placed horizontally on the table. This kind of robotic heliodon is used separately or integrated with dome artificial sky for presentation,

lighting Lighting or illumination is the deliberate use of light to achieve practical or aesthetic effects. Lighting includes the use of both artificial light sources like lamps and light fixtures, as well as natural illumination by capturing daylight. ...

design and research purposes. While in use with the artificial sky, the combined tool can replicate both the Sun and the sky for great accuracy and obtain results of the

study. The fixed scale model can be bigger and heavier models than the other types which allow the source to go around the model for obtaining evaluation results, conducting presentations and observation. The robotic heliodon allows people to move easily around and inside it for

daylighting Daylighting can refer to: * Daylighting (architecture), use of windows for indirect lighting * Daylighting (intersections), improving road visibility at intersections * Daylighting (streams), restoration of a previously buried watercourse * Dayl ...

studies. The automated robotic heliodon with a fixed model is used in research facilities, lighting companies and university laboratories such as: *

University of Kansas The University of Kansas (KU) is a public research university with its main campus in Lawrence, Kansas, United States. Two branch campuses are in the Kansas City metropolitan area on the Kansas side: the university's medical school and hospital ...

Lighting Research Lab, Lawrence,

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

uses a heliodon sunlight simulator for daylight studies and research purposes. The device was developed by Dr Hongyi Cai and custom-made in China by Quanzhou HuaTian Measurement Equipment LLC. The simulation tool has the ability of 3D angular movements of the scale model of buildings around a fixed point of the model at a precision of 0.1^o. The heliodon is installed in the darkroom for teaching purposes, research, and daylighting studies. * HFT, Stuttgart University of Applied Sciences,

Stuttgart Stuttgart (; ; Swabian German, Swabian: ; Alemannic German, Alemannic: ; Italian language, Italian: ; ) is the capital city, capital and List of cities in Baden-Württemberg by population, largest city of the States of Germany, German state of ...

uses a robotic heliodon at their Daylight Planning Lab. The lab uses two elements in their daylight simulator – an artificial sky and artificial sun. The artificial sun simulator consists of a halogen bulb with a parabolic reflector to replicate parallel sunlight. The heliodon integrated an artificial sky of 4.20m diameter with 30 fluorescent lamps. The control panel allows the replication of any solar orbit at any day and any global location. This integration facilitates the reproduction of the sky’s brightness and the circumsolar radiation in great accuracy. The architecture and design department uses the device for teaching purposes, daylight study, shadow study and research. * Bartenbach, Tyrol – the lighting firm uses a heliodon (inside an artificial sky of 6.5m diameter) with many small lamps for daylighting design with visualization models and calculations. The lighting firm uses heliodon for daylight simulation in research and development for complex building structures. The firm uses the tool for architectural lighting design used for green building certification, reports, and consultations. * United Arab Emirates University (UAEU) uses a powerful robotic heliodon made by betanit.com inside a full-dome artificial sky to evaluate daylighting of scale models with great accuracy. The heliodon is powered by a 1200W HMI lamp with a custom-designed optical setup able to reproduce a range of 200,000 lx to 600,000 lx on the table supporting the scale model. The robotic heliodon with the artificial sky is used for research purposes in

sustainable building Green building (also known as green construction, sustainable building, or eco-friendly building) refers to both a structure and the application of processes that are environmentally responsible and resource-efficient throughout a building's l ...

design and technology.

Heliodon in Lighting Handbook

Illuminating Engineering Society The Illuminating Engineering Society (IES), is an industry-backed, not-for-profit, learned society that was founded in New York City on January 10, 1906. The IES's stated mission is "to improve the lighted environment by bringing together thos ...

(IES) publishes a lighting handbook that features the heliodon as one of the tools used for the evaluation of

design. The handbook is a globally well-known reference and a guide to allow lighting professionals and practitioners to understand the impact of light on human health and promote sustainability through efficient lighting study and design. The heliodon is featured in the handbook as a lighting software tool that is used to study daylighting performance for physical scale models. It is generally used by

s and

engineer Engineers, as practitioners of engineering, are professionals who Invention, invent, design, build, maintain and test machines, complex systems, structures, gadgets and materials. They aim to fulfill functional objectives and requirements while ...

References

External links

Heliodon de Analemas
{{commons category, Heliodons Building technology