VELUX Daylight Symposium 2007

Architects' interest in illuminating building interiors with natural daylight is increasingly significant. The motivations include not only stricter regulations and standards, but also more advanced technologies that help dispel fears of significant heat loss associated with large glazing.

One proof of this interest is the second edition of the VELUX Daylight Symposium, which took place on May 7, 2007, in Bilbao, Spain. This year, it focused on daylighting in schools and presented the latest trends in developing tools for designing properly lit and sunlit buildings.
The symposium, held in the attractive space of the Guggenheim Museum, was attended by over 250 architects, designers, and educators from various European countries and overseas. Despite the significantly limited time available for individual presentations (which covered a wide thematic range), the symposium featured a variety of very interesting information and stimuli.

The moderation of the morning presentation block on the topic of Daylight and Designs of School Buildings was taken on by James R. Benya from a California university, who briefly introduced the entire issue with a note about the evolution of the approach to daylighting in schools throughout the 20th century. Since the 1930s, the importance of daylight in school buildings has been persistently underestimated in the USA and many other countries. Architects and designers have only begun to work with it again in the last two decades, partly due to significant energy savings that can be achieved with a proper design for natural lighting. One possible approach was illustrated by Benya through the example of Chartwell School in Seaside, California, a passive school building where each classroom is illuminated by a combination of side and top daylight with automatic shading and an energy-efficient lighting system PIER 4.5 (less than 9W/m²).
Of course, it was important not to overlook the generally known facts about the importance of natural light for human daily rhythms and vitamin D production. Richard Hobday from the University of the West of England in Bristol presented pioneers in researching the effects of daylight on humans and its use in medicine, among which Danish Nobel Prize laureate Niels Finsen from 1903 holds an honorable place for proving the positive effect of sunlight on killing bacteria.
The introductory theoretical block was concluded by Lisa Heschong from Heschong Mahone Group, who conducted research on light conditions in American schools. During the 1970s, classrooms without windows began to be preferred. The reasons were energy and economic savings (no unnecessary investments in shading systems, and the absence of skylights meant no risk of leaks). The research outcomes were as expected: students in buildings with sufficient daylight showed much better results (faster learning of reading and mathematics by one to two months per year). The opportunity for a view out of the window had a very positive effect (which according to another study also applies to call centers and offices).
After a rich supply of theory came a refreshing presentation by Austrian architect Hemmy Fasch from the Vienna studio Fasch&Fuchs Architects, who introduced a school for disabled children in Schwechat.
The school was established following a competition that attracted 110 teams. The jury selected the design by Fasch&Fuchs in part due to their solution for natural daylighting of all spaces. However, Hemma Fasch emphasized that they do not use any tools for the lighting design and rely solely on their intuition and experiences. Therefore, it was very interesting when Swiss engineer Christian Vogt took the stage to present the analysis results of this building from the perspective of daylighting. The average daylight factor in the classrooms ranged between 5.4-6.2%, which meets the more lenient Austrian (2-6%) or German (4%) standards, but is on the edge of the European standard (6%). Other spaces in the school performed very well or excellently, and apart from a few easily remedied areas, brightness measurements also showed positive results. Although the conclusion of the measurement was more than satisfactory, at first glance at the photographs of the glazed building, one might expect even better results – unfortunately, expert estimates in today’s context, with continuous tightening of standards, are often insufficient.
The morning block of lectures was concluded by the director of the Schwechat school herself, who praised her new school highly from the user's perspective, much to the architects' delight. The only minor criticism concerned the difficulty of cleaning large glazed surfaces.

The introduction to the afternoon part of the program on the topic of Daylight + Education + Tools was provided by Jan Ejhed from KTH School of Technology and Health in Stockholm. He considers the year 1942 a historic milestone in human history when the first fluorescent lamps were used in a manufacturing plant in the USA. Of course, humans have been using artificial light, such as from fire, since prehistoric times, and it may seem that a much greater breakthrough could have been the invention of the light bulb. However, none of these provided light similar to daylight. He followed this up with a presentation of the Arthelio system; a light guide that combines daylight and artificial light, thus ensuring a uniform illumination of indoor spaces regardless of whether it is day or night.
Belgian Dr. Magali Bodart from Catholic University of Leuven (UCL) presented some traditional methods for modeling daylighting and solar exposure of buildings using physical models. Their origins trace back to Michelangelo's model of the dome of St. Peter's, on which the famous architect tested the play of light and shadow. Despite the rapid rise of software methods, the use of physical models, real lights, and possibly cameras is still often used due to their relative simplicity and speed. At UCL, these methods remain a part of architecture education.
In cases where photographs of a lit model under cloudy skies are needed, a so-called mirrorbox can be used. This is essentially a cubic space with sides of about 3.3 m, with mirrored walls and ceiling lighting above a diffusing ceiling. This quick method is suitable for measuring the daylight factor. For examining solar exposure or the position of shadows throughout the day, a more complex so-called mechanical sun is employed – a powerful reflector on a clever rotating structure that can simulate the sun's position at any place and time.
In addition to these basic methods, there are more complex methods that are often a combination of the previous two (e.g., Tregenza, which comprises 145 lamps arranged in a hemisphere with a model on a movable platform; or the CSTC laboratory, which faithfully simulates both the sky and the sun).
Software tools were presented by Zack Rogers, who primarily focuses on modeling and developing analytical and simulation algorithms.
Analytical tools typically operate on the basis of radiosity (AGI32, Lumen Designer/Micro, or various common visualization tools like Autodesk VIZ), forward ray tracing (TracePro or Photopia), or radiance, which provides the most accurate results in terms of daylight analysis and is applied in several commercial and open-source interfaces (Desktop Radiance, Adelaine, Rayfront, etc.). Simulation tools are usually used for climate simulation (Ecotect, Climate Consultant, etc.) and determining the sun's position in the sky (Ecotect, Solar Pathfinder, or various diagrams). Additionally, there are numerous other specialized programs for designing shading, glazing, etc.
So, what could the ideal use of available software tools look like? In the preparatory phase before the actual design, it is necessary to analyze the climate in the specific location – the sun's position, the sky, and typical temperatures. Programs like Ecotect serve well for this purpose. When searching for forms, a variety of specialized analytical and simulation tools as well as common visualization tools can be utilized to determine the correct orientation of the building, simulate and preliminarily design shading, or simulate the path of sunlight over a set timeframe. In later phases of the design, as specific variants are being developed, computer models can verify the proper distribution of daylight, simulate reflections in interiors, measure brightness, determine the degree of daylighting and its changes throughout the day and year, and propose the most suitable artificial lighting. It is also possible to create detailed control visualizations to verify the use of different materials in interiors, or find the best balance between maximum energy savings and compliance with established lighting standards. Programs based on radiosity or even better radiance can be utilized.
Regarding the potential hidden within the development and easy access to software tools for everyday architectural practice, John Mardaljevic from De Montfort University in Leicester spoke. He scrutinized the daylight factor, which has been understood globally for over half a century as a method of determining proper lighting in buildings, with its minimum values usually prescribed by local regulations and standards. However, the daylight factor does not consider the orientation of the building or local climatic conditions, which means it can yield the same values for north-facing glazing in St. Petersburg as for south-facing buildings in Miami. It is based on illuminance during evenly overcast skies, while solar exposure is determined under conditions of a completely clear sky. Now, there is a more holistic approach to establishing optimal lighting for buildings – determining optimal lighting based on local climatic conditions throughout the year. As input data, local meteorological measurements can serve. Only then can one accurately design or verify the correct lighting and solar exposure of a building in a specific location.
Mardaljevic presented his method’s application at the New York Arts Students League (ASL). Besides this historically valuable building for the development of American visual arts, a skyscraper is planned to rise (upon seeing its outline, a Czech heritage preservationist would probably faint). The problem is that the ASL attic contains two studios with top lighting, which is, of course, very important for an art school. When investigating the impact of the new building on the change of daylight in these studios, standard methods failed. The skylights have a northern orientation and rarely let in direct sunlight. The daylight factor cannot describe changes due to daylight reflected from the skyscraper under varying cloud cover and at different times. The TAI (Total Annual Illumination) method was employed, which is a measurement of light energy falling on a defined surface under local meteorological conditions. The result was determining the required reflectivity of the new building's façade so that the light conditions in the studios are not seriously affected.
A fascinating conclusion to the symposium was provided by Henrik Wann Jensen. This research head at the Danish company Luxion and visiting professor at the University of California in San Diego presented the latest trends in computer lighting simulation. Luxion developed a visualization algorithm for high-tech material engineering needs that enables the computer simulation of the appearance of non-existent materials. As a by-product, a very fast visualization tool for rendering cars emerged, which was first used by Ford during a recent advertising campaign. In all media, the images were passed off as photographs, even though they were created in just a few seconds on a computer. Jensen demonstrated the visualization speed in this application on a somewhat underpowered presentation laptop. The car manufacturer thus saved a significant amount of money typically spent on two days of photographing the concept in the Arizona desert.
The results of Molecular Appearance Modeling research also seemed interesting, where materials are simulated based on their molecular properties. We might encounter this method eventually in standard visualization tools for architects, as it could be used to simulate a blue sky at any place and time. Luxion is also involved in the development of a free tool for simulating and analyzing daylighting called the VELUX Daylight Visualiser, whose upcoming second version will allow for even basic modeling.

At the end of the symposium, a rather interesting discussion erupted among the speakers and the audience in the hall. Several participants shared Jan Ejhed's concerns that with the use of increasingly sophisticated yet user-friendly software tools, a certain creativity and individuality may dissipate from architectural design, and many architects could become victims of these tools, working only based on the results of lighting simulations. Similar to working with CAD programs, it holds true here that architecture is not created on a computer screen, but in the architect's mind. Some presenters pointed out that the current most prevalent use of these tools is merely for visualizations, wherein programs designed for completely different fields than architecture dominate the market. However, the real benefit of today's easily accessible software tools should not be seen in the creation of photorealistic visualizations for presentation purposes, which are usually processed in terms of lighting with the goal of achieving the most effective result rather than capturing real light conditions (very few such purely animation and visualization tools also allow lighting scenes using quantities used in building physics). Much more important is the easy computation of lighting and light-technical simulation, where visualization is just one of the resulting outputs.

As part of the accompanying program, there was also an opportunity to visit several projects that have emerged in Bilbao (in addition to the Guggenheim Museum, it included Calatrava's Sondika Airport, the de Sarriko Conservatory, the Euskalduna Congress and Concert Center, etc.) or to tour the Atika project, which the VELUX company has built upon the concept of Soltag from the year before last (we will soon present Atika separately on Archiweb) and a related shorter series of lectures on designing energy-efficient buildings.

The symposium did not provide participants with a complete guide on how to approach the design of schools and other buildings regarding daylighting or what specific software tools architects should immediately acquire for their work. However, it did offer numerous practical impulses and ideas to ponder. One thing is certain: the latest trends in illuminating buildings with natural daylight are something that cannot be overlooked in contemporary architecture.

For more information about the symposium, individual presentations, and many other materials, please visit thedaylightsite.com.