INTRODUCTION
This article is aiming it both, presenting value of integrated system solution within building technology and proposing redesign one of analyzed building in this matter. Author will try to present various examples of integration aspects between building elements at booth local (detail) and global (space) scale of the building, developing a patch of evolution within way of thinking about integrated solutions.
EVOLUTION OF INTEGRATION (EXAMPLES ANALYSIS)
First lets take a look at actual architectural examples, showing evolution and grooving value of integrated solutions within building science. This way we will understand that aspect of integration has been always present in the architectural design, an the one thing that is changing is the complexity of integrated solutions.
Office building Westraven in Utrecht, Netherlands by Cepezed (pic.01) generates a field of proving value of integrated system. What is even more valuable about considering this particular building, is a fact, that it was completely renovated after only 30 years of usage, and despite the fact that purpose of the building was preserved, the solutions used within its technology are newer, and ass we will see much more integrated into each other then it was before. Only think that was left from the old building was the structure. Facades, interiors and all building utilities were redesign considering demands of future users and environmental responsibility.
First, and one of most interesting integrated solution used within domain of high-rise building “wall” is the facade system used in Westraven. The facade fabric around the high-rise block not only provides shelter from the wind but also tempers the sunlight. Material used here within double skin-facade system are glass and carbon-fibre fabric (ex. carbon fiber-reinforced polymers), which was use in this contexts for the first time. Carbon fibres are extremely strength (tension strength is 5 times bigger the within the steel), durable and light which makes it perfect solution for outer layer of the facade, creating wind pressure and sun shelter.
Second inspiring integrated solution used both, to preserve efficient height of interior spaces in the building and to minimize structural demands of the building, was technology of integrated floor panels designed, and developed within Cepezed office, mainly as a solution for Westraven. IDES floor is composed out of steel floor elements with a thickness of only 31 cm in which the construction and the installations are integrated.
Last, but not the least, mentioned here, is one of the first usage of ETFE membrane in a large scale building. The aspect of integration in this example extends its meaning from the local interaction between elements onto the global scale relations in the building. In Westraven it was used both, as a single membrane (open roof of central garden area) and cushions (North - East facade) (pic.02). Cepezed architects took advantage of low-thermal insulation parameters within still relatively new and undeveloped ETFE technology, and turn those in to climate zoning solution within the building. Still, it doesn’t means that this technology cannot be use to create well insulated interior spaces, taking advantage out of the other material features. As showed before, it has higher thermal insulation efficiency then the similar glazing solutions.
The best example of how does ETFE can be combined with other solution to act as a fully functionally, active and energy efficient building skin is WaterCube Beijing swimming pool building, designed by PTW Architects in collaboration with ARUP for Olympics Games in China. The level of integration between materials, facades, system and structure in this building melts down those various aspects into one global integrated solution. ETFE material had been used here no only as a physical division between inside and outside
Integration level in different buildings varies depending of their destination, used materials and technical constrains. Taking, for example, analysis performed on Westraven and WaterCube it is very clear to see how does certain technologies evolve during time. Westraven was one of the first example of usage ETFE membrane with it early limitation where WaterCube is an example of how does this new technology can be adjusted to achieve high building performance, as well on the layer of energy efficiency as on the layer of controlling internal climate of the building.
INTEGRATED COMPONENTS (MATERIALS AND SYSTEMS DATA)
When saying about extending building element capabilities it is necessary to be familiar with particular material and it’s proprieties. Concentrating around reveling hidden potential of ETFE technology, lets have a brief look onto this material and the technical extensions that can be integrated with it.
ETFE membrane (pic. 03) (ethylene tetrafluoroethylene) was developed over 30 years ago but its architectural implementation are relatively new. It is typically used as a transparent (up to 95%) foil, with a thickens from 0.12 to 0.5 mm (within building domain - depending on destiny) to form single layered membranes or multi layered air-pillow systems. Thanks to its lightness (ETFE density is ~3kg/ m3 comparing to glass ~2500kg/m3) and flexibility it is extremely easy to transport and can be used with very light supporting structures. Moreover, installation cost are estimated to be 25% to 75% lower then in terms of glass panels. Also in terms of thermal insulation double layered ETFE membrane (single cushion 0.2 mm ETFE + 300 mm air space + 0.2 mm ETFE) has estimated 2,6 W/m2K insulation parameter where typical two layered glass window (6mm glass + 12 mm air space + 6 mm glass) has the same parameters at the level of 3,3 W/m2K. Finally maintaining costs are also lower due to ETFE self-cleaning ability, similar to those generated by Teflon membranes. Material has also class A fire resistance, it is not melting due to the fire impact, and it is 100% recyclable. ETFE foil can be color and opacity can be adjusted within production process, it is also possible to create an random non transparent imprint on to ETFE surface. Due to material structural stiffness and flexibility after installing, it is able to be composed with other thin flexible layer systems, such as, flexible PV (photovoltaics imprinted onto 0,5mm polymer substrate foil). The process of integration is based on laminating Photovoltaics between two layers of ETFE film (pic. 06). Assuming efficiency of thin-film PV system at statistical level of 100 W/m2 total energy produced per 5 hours sun duration in a clear sky day is around 0,5 kWh/m2.
INTEGRATION (REDESIGN PROPOSAL)
It was mentioned before, that ETFE solution in Westraven building has been used on North-East facade of low-rise building as a external-internal division creating only partly isolated space of entrance court. The intentions on the architect was to achieve different micro climate for climate zoning purposes inside the building. Solution based on the same material might be used also on the South-West facade of low rise building, but the technology was not evolved enough to allow proper thermal performance and sun-shading abilities. That is why architects used double glazing facade integrated with mechanically controlled shades. Nevertheless, performance achieved this way is the reason of many complains coming from the users of the building. First of all, during the summer, it is overheated, secondly, the interior space behind the facade is often used as a presentation area for a big events, which generates light control problem by inefficient mechanical shading system.
The solution for this problem might be to redesign the upper part of the facade in ETFE technology, similar to this one used in WaterCube building, where not only thickness of both, external and internal layer of the ETFE membrane differs depending on actual need, but also such integrated solution as sun penetration control and energy possessing technology were integrated into design of each ETFE pillow, allowing fully control over desired parameters of the interior space. This way it is possible to preserve original facade division and architects intention in terms of high transparency, adding new quality to it’s behavior. Replacing double glazing filling with double ETFE pillow system with the pattern imprinted onto inside pillow, as well as photovoltaic cells integrated into outside layer of the outside pillow, it is possible to achieve completely new quality of the space.
First thing is adjusting ETFE pillow membrane thickness to its destination. For each air-pillow solution propose total 4 layers of ETFE External layer should be thicker then the internal, where both layers of internal pillow can be also relatively thin, as they will work mainly as a shading system.
Secondly, inside pillow needs to be imprinted with overlapping shading patters, allowing increasing or decreasing opacity of the pillow, depending of distance between two layers and the angle of sun penetration.
Third thing is assuring separate air supply for both external and internal component of each pillow, so does the one system works as a constant air pressure control (ETFE pillow system demands constant air supply) and the second one to control volume of internal pillow in order to allow or deny sun penetration it the building. Air pressure system needs to be supported by boot main air pump (as a constant low pressure supply) and air compressor (as a dynamic air supply for internal pillows). Air is distributed by PVC piping hidden in a elevation structure profile. Depending of location and aesthetic demands piping it stiff and transparent (outside pillow connection) or flexible (inside pillow connection). Energy consumption generated by this solution can be partly recompensed by implementing thin photovoltaic cells on a flexible PVC layer, imprinted between doubled external ETFE layer. Sun shading ability, due to the fact that it is needed on sunny days, can be completely self-sufficient in terms of energy usage.
CONCLUSIONS
ETFE integrated systems can be used as a physical space division, shading system and energy possessing source all in one solution. Working with integrated system technologies, as showed on a previous example, it is possible not only to improve particular building element, but it can also significantly increase building global efficiency. Such aspects as internal climate control or energy consumption needs to be considered at the level of detail design.
Integration within building details is already important aspect of building technology and taking into consideration miniaturization and integration tendencies visible in other branches of industry and science, this tendency will continue to grow, generating even more effective solutions and at the same ti extending domain of architecture into even more dilettante discipline then it is now.
BIBLIOGRAPHY
Baraona P. E. “Watercube: The Book” Actar 2008
Beijing Institute of Architectural Design “Olympic Architecture: Beijing 2008” Birkhäuser 2008
deLanda M. “War in Age of Intelligent Machines” MIT Press 2003
Garber R. “Closing the gap. Information Models in Contemporary Design Practice” Wiley 2009
Hwang I. “Verb Natures. Architectural Boogazine” Actar 2008
Koekebekker O. “Westraven Office Building for Rijkswaterstaat”, 010 Publishers 2008
LeCuyer A. “ETFE Technology and Design” Birkhäuser 2008
Theunissen K. “Re-opening the Dutch city block” p. 203 - 220 Arc vol.10, 2006
Ritter A. “Smart Materials”, Birkhauser 2007
Weller B., Hemmerle C., Jakubetz S. “Detail Practice: Photovoltaics: Technology, Architecture, Installation” Birkhäuser 2010