| Building envelopes are the separating and filtering layers between the outside and the inside, between nature and adapted spaces occupied by people. In historic terms, the primary reason for creating this effective barrier between interiors and exteriors was the desire for protection against a hostile outside world and adverse weather conditions. Various other requirements and aspects have been added to these protective functions: light transmission, an adequate air change rate, a visual relationship with the surroundings, aesthetic and meaningful appearance etc. Accurate knowledge of all these targets is crucial to the success of the design as they have a direct influence on the construction. They determine the amount of energy and materials required for construction and operation in the long term. In this context, transparent and translucent materials play an important role for the building envelope as they not only allow light to pass through, but also energy. Glass has attracted architects from the very beginning used intelligently with: plastics, perforated metal plates, meshing and membrane materials, which can also withstand structural loads.
Earlier applications of glass in composite use with other façade elements have served the purpose to keep off sun, wind, rain and snow while offering the advantage of well lit enormous span widths and a great variety of shapes.
The use of glass in small or large scale projects are aimed for a forward-thinking and resource friendly technology which is able to merge different aspects, from high quality design, to function and comfort. The design must strive for high standards with respect to the building envelope. In order to achieve adequate energetic and comfortable interior conditions, constant cooling, dehumidification and a sufficient reduction of solar gain is required. For the passenger concourses a special triple glazing glass has been developed allowing for 1-2% of the sun light. The possibilities are endless as mentioned ahead.
Allowing light to penetrate as diffuse light thereby granting a general illumination inside during the day. At the same time, the low e glass roof system reduces the heat emission of the hot roof to the insides by approximately 40%. This can be achieved using a special low-E coating on the inner layer. Sound insulation against aircraft noise from outside and acoustic absorption for interior comfort comply with the requirements.
The function of weather protection against rain and snow has been separated from the thermal protection of the building envelope. As the outer shell, a single layer, transparent ETFE-Glass is spanned granting maximum radiative permeability for day lighting. Underneath, the film-layer elements are placed both fixed and moveable in order to allow adjustment of light input according to the requirements within the rooms situated below. Due to the antiadhesive surface quality of the ETFE-material the cleaning costs are reduced compared to normal glass. The glass construction follows the intention of the architects to obtain a nearly invisible skin, allowing full visibility from interior to exterior and vice versa and using filigree, non perforating clamping technologies.
This includes the work on passive measures such as the further improvement of solar gain control and heat protection, thermal insulation, acoustic and daylight-properties.Active technology like photovoltaic and solar thermal collectors will play an important role as a complement to glass structures but also as stand-alone applications. Special emphasis will be put on ‘solar cooling’ which allows to use solar generated heat to be directly converted into cooling energy. This technology will be of significant importance in the moderate, subtropic and tropic regions in the process of a global change to renewable energies. Self cleaning glass will also be a forerunner in the use of exterior maintenance free glass facades.
The intelligent use of intelligent glass paves the way forward for a sustainable future and building envelopes are the major route to be strengthened using intelligent glass as the tool of the future. |
