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 between a horizontal plane at a specific latitude and the solar beam. Heliodons are used primarily by architects 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.
Shortly after World War II, in the 1950s, there was a wide interest in producing building design techniques that correspond to the climate. [1] At Princeton Architectural Laboratory, Thermoheliodon was invented by Olgyays in hopes to create physiological conditions of human comfort through architectural design. Thermoheliodon was a domed insulated evaluation bed for scaled architectural models in certain climatic conditions measured to a high level of calculation and accuracy. [1] The device was a covered simulating environment where a scaled model’s thermal performance could be evaluated under different temperatures. [1] 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 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. [2] The institution aimed to enhance housing conditions and development of local resources for construction in colonial territories. [2] Heliodon was designed to replicate the sun on architectural scale models through a point of light. [2] The device can shift and tilt to obtain the accurate position of the sun on any given day, time, or location. [2]
In the 1960s, a heliodon was invented by Gershon Fruhling in Israel, recorded by the United States Patent Office. [3] This heliodon consists of a platform created to hold a model of the building whose isolation is to be evaluated. [3] 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. [3] The titling of the shaft enables the adjustment to various geographical locations on the latitude scale. [3] 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. [3] 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. [3]
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. [4] This heliodon is combined with a sky scanning simulator (artificial sky) to predict the light distribution in a building over the entire year. [4] The device can reproduce direct light at any location on Earth. [4]
After the 2000s, Prof. Norbert Lechner, an architect, LEED AP and an expert in energy responsive architecture has invented a manual Sun Emulator Heliodon. [5] He invented heliodons which were much easier to evaluate daylight simulation than the previous models. [5] The Sun Emulator Heliodon can precisely show all solar responsive design principles and strategies. [5] 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. [6] 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. [6] Moreover, the Orange Heliodon was used at Politecnico di Milano in the architectural design laboratory of the BEST department. [7] It used a computerized and automatic heliodon to reproduce the sunshade. [7] 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 daylight studies. [6]
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. [8] Moreover, a tabletop heliodon with a moving light source was developed for architect 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 architectural models or building components.
The Earth is a ball in space perpetually intercepting a cylinder 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 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, 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. 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 (in June) to the Tropic of Capricorn (in December) and back again. This changes sun angles all over Earth according to the date. See more at analemma.
Heliodons can mimic latitude, 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.
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 architectural model. [9] 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. [9] 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. [9] 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. [9] 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. [9]
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. [5] The heliodon can be used to teach solar geometry and solar responsive design principles in science museums. [5] 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. [10] 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:
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:
This robotic heliodon is fully automated with a computer 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 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 daylight 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 studies.
The automated robotic heliodon with a fixed model is used in research facilities, lighting companies and university laboratories such as:
Illuminating Engineering Society (IES) publishes a lighting handbook that features the heliodon as one of the tools used for the evaluation of daylighting design. [23] 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. [23] The heliodon is featured in the handbook as a lighting software tool that is used to study daylighting performance for physical scale models. [23] It is generally used by architects and engineers.
Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere as daylight when the Sun is above the horizon. When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat (Atmospheric). When blocked by clouds or reflected off other objects, sunlight is diffused. Sources estimate a global average of between 164 watts to 340 watts per square meter over a 24-hour day; this figure is estimated by NASA to be about a quarter of Earth's average total solar irradiance.
In passive solar building design, windows, walls, and floors are made to collect, store, reflect, and distribute solar energy, in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design because, unlike active solar heating systems, it does not involve the use of mechanical and electrical devices.
Daylighting is the practice of placing windows, skylights, other openings, and reflective surfaces so that direct or indirect sunlight can provide effective internal lighting. Particular attention is given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy use. Energy savings can be achieved from the reduced use of artificial (electric) lighting or from passive solar heating. Artificial lighting energy use can be reduced by simply installing fewer electric lights where daylight is present or by automatically dimming or switching off electric lights in response to the presence of daylight – a process known as daylight harvesting.
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. Daylighting is sometimes used as the main source of light during daytime in buildings. This can save energy in place of using artificial lighting, which represents a major component of energy consumption in buildings. Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants.
Environmental design is the process of addressing surrounding environmental parameters when devising plans, programs, policies, buildings, or products. It seeks to create spaces that will enhance the natural, social, cultural and physical environment of particular areas. Classical prudent design may have always considered environmental factors; however, the environmental movement beginning in the 1940s has made the concept more explicit.
A heliostat is a device that includes a mirror, usually a plane mirror, which turns so as to keep reflecting sunlight toward a predetermined target, compensating for the Sun's apparent motions in the sky.
Architectural lighting design is a field of work or study that is concerned with the design of lighting systems within the built environment, both interior and exterior. It can include manipulation and design of both daylight and electric light or both, to serve human needs.
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. Sunlight scattered or reflected by astronomical objects is generally not considered daylight. Therefore, daylight excludes moonlight, despite it being reflected indirect sunlight.
Sustainable architecture is architecture that seeks to minimize the negative environmental impact of buildings through improved efficiency and moderation in the use of materials, energy, development space and the ecosystem at large. Sustainable architecture uses a conscious approach to energy and ecological conservation in the design of the built environment.
Building science is the science and technology-driven collection of knowledge in order to provide better indoor environmental quality (IEQ), energy-efficient built environments, and occupant comfort and satisfaction. Building physics, architectural science, and applied physics are terms used for the knowledge domain that overlaps with building science. In building science, the methods used in natural and hard sciences are widely applied, which may include controlled and quasi-experiments, randomized control, physical measurements, remote sensing, and simulations. On the other hand, methods from social and soft sciences, such as case study, interviews & focus group, observational method, surveys, and experience sampling, are also widely used in building science to understand occupant satisfaction, comfort, and experiences by acquiring qualitative data. One of the recent trends in building science is a combination of the two different methods. For instance, it is widely known that occupants' thermal sensation and comfort may vary depending on their sex, age, emotion, experiences, etc. even in the same indoor environment. Despite the advancement in data extraction and collection technology in building science, objective measurements alone can hardly represent occupants' state of mind such as comfort and preference. Therefore, researchers are trying to measure both physical contexts and understand human responses to figure out complex interrelationships.
The Eastgate Centre is a shopping centre and office block in central Harare, Zimbabwe, designed by Mick Pearce. Designed to be ventilated and cooled by entirely natural means, it was probably the first building in the world to use natural cooling to this level of sophistication. It opened in 1996 on Robert Mugabe Avenue and Second Street, and provides 5,600 m² of retail space, 26,000 m² of office space and parking for 450 cars.
Light tubes are structures that transmit or distribute natural or artificial light for the purpose of illumination and are examples of optical waveguides.
Sustainable lighting is lighting designed with energy efficient light sources. "There are simple design strategies and some materials that can facilitate the energy saving advantages of natural light. Light colored interiors and open floor plans are good choices. This approach also augments artificial light efficiency. Energy efficient lighting is not simply finding the most light for the least wattage or the longest lasting light bulb. Proper sizing of the light to the needs of the location and the tasks that will be performed, called task lighting, is an energy saving strategy."
Solar access is the ability of one property to continue to receive sunlight across property lines without obstruction from another’s property. Solar access is calculated using a sun path diagram. Sun is the source of our vision and energy. Its movements inform our perception of time and space. Access to sun is essential to energy conservation and to the quality of our lives.
In architecture, a daylight factor (DF) is the ratio of the light level inside a structure to the light level outside the structure. It is defined as:
A skylight is a light-permitting structure or window, usually made of transparent or translucent glass, that forms all or part of the roof space of a building for daylighting and ventilation purposes.
The following outline is provided as an overview of and topical guide to solar energy:
Photopia Optical Design Software (Photopia) is a commercial optical engineering ray-tracing software program for the design and analysis of non-imaging optical systems. Photopia is written and distributed by LTI Optics, LLC and was first released in 1996. Photopia's main market is the architectural lighting industry but it is also used in the automotive, medical, industrial, signal and consumer products industries. Photopia includes a full library of lamps including the latest high brightness LEDs as well as a library of material BSDF data.
In building engineering, a climate-adaptive building shell (CABS) is a facade or roof that interacts with the variability of its environment in a dynamic way. Conventional structures have static building envelopes and therefore cannot act in response to changing weather conditions and occupant requirements. Well-designed CABS have two main functions: they contribute to energy-saving for heating, cooling, ventilation, and lighting, and they induce a positive impact on the indoor environmental quality of buildings.
The artificial sky is a daylight simulation device that replicates the light coming from the sky dome. An architectural scale model or 1:1 full-scaled aircraft is placed under an artificial sky to predict daylight penetration within buildings or aircraft that subjects to different situations, complex geometries, or heavily obstructed windows. The concept of the artificial sky was derived due to heliodon’s limitation in providing a stable lighting environment for evaluating the diffuse skylight component.
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