Air Filled and Tension Skinned Architectural Membranes in ETFE, PTFE and PVC
ETFE, PTFE and PVC
Novum has three distinctive system products ideally suited for the innovative implementation of distinctive architectural membrane enclosures. In-house design and patterning are core skills of our company and we fabricate many different materials in our state-of-the-art German membrane production facility. The bulk of our projects use ETFE, but we also fabricate Tenara, PTFE and PVC materials. Novum Membrane Systems have uniquely different aesthetics and each one features a distinctly different approach to delivering the necessary surface tension.
Air Filled Pillow. Depending on project specific thermal performance requirements, ETFE pillows are comprised of 2, 3 or 4 layers of membrane which are edge welded into sealed units. The thickness of each layer is determined structurally and varies from 100 to 500 microns. Any layer can be printed for shading and a variety of prints and custom options exist, including reverse printed operable layers. Profiles can be anodized, or powder coated. Pillows are air filled under low pressure by dual chamber pumps and varied sensors and controls are available. Novum’s in-house software predicts potential prone areas and adjusts the geometric form to avoid any wrinkles.
Air filled pillows are very large in comparison to conventional metal, plastic or glass cladding panels allowing nominal structure and a different architecture than conventional cladding requires. Hence, integrated pillow and structure is faster to site, quicker to build and highly economical. A further advantage of the system is that pillows readily fit to warped surfaces. Conventional rectangular pillows can be very long over 200’ (60m) with varied widths depending on environmental loadings. Pillows can be any shape, triangular through octagonal, and have been successfully used in complex freeform structures.
ETFE material allows light to migrate along its surface, introducing exciting ways to use lighting effects, which is of great interest in public spaces, arenas, retail applications and more. Plants thrive below ETFE due to its thermal properties and the system is designed with recycling and corrosion resistance in mind.
Applications vary but include atriums, roofs, canopies, walls, lighting/marketing displays, sports arenas, swimming centers, horticultural/garden centers, transportation hubs and more.
Stressed Skin Membrane. The SSM-System varies depending on material type. An incredibly light single skin system uses a single layer of ETFE with biaxial tension applied by low force perimeter tensioning. The perimeters and panel intermediates are realised from aluminum extrusions which are anodized, or powder coated. The intermediates often use internal guttering. Additional transverse load transfer can be provided by thin prestressed stainless-steel cables in ETFE pockets on the lower side of the surface. Cable spacing is determined from environmental loads and the drainage needs very careful planning as the ultra-light system is flexible and deflects easily. Typically, the cables are one directional and spaced at around 2’ (600mm). The weight is below 1 psf (0.05 kpa) making it arguably the lightest enclosure system on the market. Where smaller pre-made aluminum framed panels are feasible, cables are eliminated and the system is unitized. ETFE in a single skin system has a very nominal thermal performance and shading is best accommodated by using colored, solid or translucent material.
The SSM-System for more robust designs using PVC and PTFE materials require higher prestress which is applied using heavier edge profiles. Typically, the materials are stretched over spaceframe grids or stiff steelwork to limit membrane spans so that cables are not required, and tension forces are held within the steelwork. Once stressed, clamping bars are applied as required to prevent uplift. PVC and PTFE materials vary in opacity, but are not transparent.
Applications include canopies, small span ribbon skylights, screens, walkway covers, shade covers and green areas.
Cable Tensioned Fabric. Our CTF-System uses membranes in the more classical “tent” architecture and rely on surface shape for biaxial tensioning of woven materials, typically PVC and PTFE. The form of the membrane is double curved, and the surface tension is normally applied via catenary cables in perimeter pockets, though straight edges can be achieved with steelwork and heavy clamping fixings. A mix of cable stays and masts support the roof and are provided single source by Novum using our AES-System + TR-System. In high wind areas, cables may be used over the surface to control uplifts. Perimeter cables are usually galvanized for economy.
Regarding material choice, PTFE has a superior lifespan than the more affordable PVC. Architecturally, PVC is available in varied opacities and multiple colors.
Applications include pavilions, shade structures, sports and recreational facilities, canopies, awnings, temporary and emergency covers.