Towards the age of the sun
By Christer Nordstrom-Arkitektkontor AB
Throughout history roofs have been the most important aspect of men’s dwelling place-providing shelter from rain, snow and sun. From their design we can determine the traditions, craft, status and culture of the people who build them and the climatic conditions with which they had to cope. Thus, as we enter into the “solar age”, it is necessary to remember that roofs are an important part of our cultural heritage. The integration and treatment of solar panels within modern structures not only heralds a new are in energy production but is also a historic architectural turning point.
Active water and air-based solar collectors and PV panels are a new invention that should be given new forms based on their function. This coheres with tradition in that practical considerations have always dictated the design of roofs-for example overhanging to keep the snow out, glass roofs to let in the daylight and chimneys to provide a stack effect for ventilation. It would seem illogical to attempt to “hide” solar collectors be making them look like conventional roofs. The essence of a solar collector is in fact opposite to that of a conventional roof-instead of sheltering us from the natural elements it reaches out to the sun to capture its energy. The new and true function of a solar roof should be clearly shown and celebrated within a building’s design.
On the other hand, it is important to integrate solar collectors into existing buildings with care. A successful balance between these two ambitions is necessary in establishing a form of architecture which shows respect for history whilst at the same time points towards the future.
Besides solar energy the new-born interest in natural stack ventilation and daylight techniques will certainly have an influence on the roof designs of the next millennium. Recent designs demonstrate how a modern rethink of thus techniques can be applied to old as well as new buildings. The study of “old” innovations for ventilation and daylight in palm houses, glass covered galleries and stack towers, might lead to both improved energy-saving methods and optimal architectural integration.
Just like all designers throughout history, modern solar architects have their limitations defined be climate, access to local materials, and prevailing cultural building traditions. A Scandinavian solar roof will not and should not look like one builds in southern Europe because of the differences in climatic a cultural conditions. However, this does not mean that each country should develop their own techniques in isolation. International co-operation has taught me that we have a lot to learn from sharing ideas and experiences between the European countries. Let us keep our minds open and work together towards the age of the sun.
Wind directions, November, 2001
Questions for text:
Why do we consider roofs as a part of our cultural heritage?
Speak on the functions of solar collectors and PV panels.
What will an influence on the roof design be?
What ca you say about solar roofs in different countries?
Passive Solar and Daylight
By Poul E. Kristensen – DTI Energy Vision
The roofs and facades of buildings have multiple functions – providing shelter for rain and wind, and a barrier for high or low external temperatures. However the growing concern to Reduce energy consumption and pollution has led to additional functional Requirements of the roofs and facades of buildings.
The environmental impact of building can be minimised effectively by utilizing heat and light from the sun. The roofs and facades can be used as active filters of solar power. The integrated energy facades is the key building element in achieving this. Two research projects of the European JOULE Research Programme illustrate this transition of the building envelope from a passive climate protection to an active energy filter for the building.
Design Center in Linz
The 31.000 m2 design center in Linz Austria has a fully glazed envelope, consisting of double glazing with integrated microlouvres. These microlouvres are designed so that all direct sunshine is redirected out of the building. Only diffuse light is allowed to enter this exhibition building, providing ample daylight at an even distribution.
The filtering of direct sunlight from diffuse light is made possible through the design of the fixed louvres so that the correspond to the specific orientation and slope of the roof, and the latitude of the site. Radiation from those parts of the sky where direct solar radiation can occur is cut off, whereas diffuse radiation from the rest of the sky is allowed to enter the building. This innovative glazing system was developed by Lichtplannung Bartenbach in Innsbruch Austria, and it is produced by Siemens in Germany. The architect of the Design Center is professor Thomas Herzog from Munich Germany.
The Brundtland Center in Toftlund
The Brundtland Centre in Denmark is a 2000 m2 office and exhibition building. The architect of the building is KHR Architects in Virum DK. The energy design and engineering is by Esbensen, Consulting Engineers in Sonderborg, Denmark.
The two storey building is designed around a central glazed atrium. This atrium serves as a thermal buffer zone for the adjacent building, and provides passive solar heating. The root of the atrium is a shed roof, with clear glazing to the north. The south sheds are utilised for production of solar electricity. The photovoltaic PV elements are integrated in the glazing, allowing only a small part of radiation from the south to enter the room. The glazing has a u-value of approximately 15 W/m2K.
The PV elements of the roof can thus serve multiple purposes providing shelter for wind and rain, thermal insulation and shading, and solar electricity and natural daylight for the building. As the advances in glazing and PV technologies accelerate, we come closer to building homes and offices that will make a positive impact on the environment - by producing more energy than they consume throughout their lifecycle.
Wind directions, November, 2001
Questions for text:
Tell about functions of buildings, roofs and facades.
What are they used for?
Speak on the design center in Linz (Austria).
What can you say about the Brundtland Center in Toftlund?
Describe functions of PV elements of the roof.