Sustainable Buildings on Demand

Originally engineered to solve the problems of relocatable or temporary shelter, tensioned membrane structures are now a sustainable choice for permanent, habitable structures, providing fast, energy-efficient and affordable building solutions.

Celeste Allen Novak AIA, LEED AP

Tensioned membrane buildings provide an opportunity for a new sustainable design approach for any building program that requires column-free and open-span floor plates. New tensioned membrane buildings are sited in deserts as well as snow-covered mountains with segmented grace. These buildings can provide immediate, cost-effective alternatives to conventional construction, for facilities that range from dormitories, churches, and offices, to gymnasiums. Tensioned membrane structures have been around since the 1960s, often used by the military. When oil and gas companies required shelters for both arctic and desert climates that could be easily transported across the world, engineers developed an energy-efficient portable building system.

Their solution has been refined and developed into a new building type-permanent, habitable tensioned membrane structures. These buildings can be erected quickly and cost-effectively, maintaining similar performance and aesthetic values to conventional structures, but with a lower cost basis of thirty-five to fifty percent. Architects who have worked with these forms can attest to the difference and quality of these durable, affordable, flexible and energy-efficient buildings.

This course will review the aesthetics and attributes of tensioned membrane buildings and provide information on how they can fit into a sustainable design portfolio in any climate, delivering energy efficiency and durability for clients who need affordable and immediate building solutions with an optional insulation package.

In the introduction to the Whole Building Design Guide , a program of the National Institute of Building Sciences, Richard Rush is quoted as defining an integrated building system by only four systems: structure, envelope, mechanical and interior. "The envelope has to respond both to natural forces and human values. The natural forces include rain, snow, wind and sun. Human concerns include safety, security, and task success. The envelope provides protection by enclosure and by balancing internal and external environmental forces. To achieve protection it allows for careful control of penetrations. A symbol of the envelope might be a large bubble that would keep the weather out and the interior climate in."¹ Tensioned membrane structures provide many environmental, as well as aesthetic, advantages in an integrated building system.

A Biomorphic Vocabulary-Design Principles

Begun as a mid-twentieth century art movement, biomorphic artists focused on organic shapes inspired by biological forms and processes. Abstract and often surrealistic, these forms expressed an alternative to realism and static, orthogonal objects. One of the most recognized biomorphic artists today is Dale Chihuly, whose glass botanical forms are often inspired by nature as well as inserted in natural landscapes. Biomorphism in architecture has taken many directions as a movement. Architects are studying the design of vaguely organic forms as well as creating new buildings that not only replicate shape but also emulate biological processes. There is a new desire to learn from nature in order to design sustainable buildings. A highly engineered, integrated system, a tensioned membrane structure has an organic, biomorphic form as well as an efficient, technological response to climate and natural processes. Design professionals have new opportunities to explore alternatives to big box construction, within the framework of a sinuously curved, rounded volume.

Architect David Simpson, principal of David M. Simpson Architects in Greenville, South Carolina, continues to be amazed by the aesthetic and massing of the 48,000 square-foot Redemption World Outreach Center, which he designed using a tensioned membrane building. The client had seen a similar project that was constructed in Florida and asked Simpson to see if this might be an affordable solution for their fitness facility. They liked how the membrane-covered frame structure looked as well as the promise of an early completion through this fast, modular construction process. They also liked the resulting bright, clear span, daylit and energy-efficient space.

This 120-ft wide by 300-ft long tensioned membrane building is currently being used by the entire community as a fitness center, gymnasium and recreation complex. The structure was delivered in mid-February of 2009 and the facility opened in mid-June of that same year. The monolithic enclosure was installed within a nine-week period not including the slab or footing construction, or the interior skeleton or walls. According to the building contractor, Lynn Wiley of Daystar Construction, "The client wanted a "wow" factor and got it in this unique building. The structure was simple to construct."

Church members shared the excitement of watching this unique facility being constructed and often commented on each stage of the process. Most were astonished at the rate at which the building was completed. They are pleased by this comfortable daylit enclosure that is home to their new fitness facility.

The building houses three full size basketball courts, and each round end of the structure has a 12,000sf mezzanine level with meeting rooms, weight rooms, aerobics rooms, cardiovascular equipment, and locker rooms complete with two separate sauna areas. The perimeter of the structure has a raised, 1/5th-mile running track that overlooks three basketball courts.

Lighting, fire suppression, sprinklers and the HVAC systems were either suspended in the structural beams by way of attachment brackets. The brackets are held in place by bolts in an extruded bolt chase. The HVAC system was mounted outside the structure on a platform to avoid a conflict with the running track. An entry addition was added to the building, designed by the architect and attached with input from the manufacturer as to flashing and connection details. Doors and windows connections were supplied by the manufacturer and were installed as part of the structural system. The construction team included a manufacturer's representative who made sure that the installation had minimal disruptions or delays. The envelope is filled with R-30 formaldehyde-free insulation. The two-membrane layer combined with an insulation filling creates an airtight envelope that provides lower energy costs.

As with any engineered system, the designer has a set kit of parts that needs to be adapted to the client's program goals. Tensioned membrane buildings can be curved along a two-dimensional spine, or contain the program under a singular, domed shape. The skeletal frames can have either rounded or flat ends. The designer can choose to add windows, doors and external rooms, as shown in the entry canopy and lobby for the Navajo Fire Rock Casino. These structures can also become additions to existing buildings with a sealed connecting corridor system. These corridors can range in size in width from ten to nineteen feet. The advantages of a tall, vaulted and column-free structure is that the design professional can work within a flexible, open interior volume to insert an independent system of walls, mezzanines, entries, etc.

Membrane buildings are a new place for art. The surfaces of these buildings create a new and expressive design opportunity to develop surface designs, patterns and symbols. In choosing a tensioned membrane structure for Navajo Fire Rock Casino in New Mexico, the client selected this form for the speed of construction. They soon realized the aesthetics and quality of this building also met their vision for a permanent structure. The tribe chose to imprint Native American symbols on the canvas of their building membrane, an aesthetic reference to the tents that once marked Indian settlements.

Sustainable Building Components

Engineered tensioned membrane structures have several components. Modular, vaulted frames are assembled as a system braced by intermediary members. The design professional chooses a shape along a sine curve to determine the placement of the frames developing the spine of the building. The frames can be spaced approximately fifteen feet apart on center, along an unlimited building length. However, the building width is limited and manufacturers may provide the design professional with options from a smaller span, for example a 30-foot frame, up to a large clear span of as much as 200 feet. Aluminum frames extend to a peak and back and are sloped at 26 degrees for the most effective means to prevent snow or ice accumulation. The skeletal frame members are designed with opposing flanges, providing a cavity to receive the finished exterior and interior membrane as well as the insulation filling.

The materials and their environmental benefits that comprise these systems include bolted aluminum frames, architectural coated interior and exterior membranes, optional formaldehyde-free insulation packages and skylights, window and door systems.

Aluminum Substructure

Aluminum is durable, long lasting and one of the most recycled metal products in today's market. Aluminum frames used as the skeletal spine are as easy to mount into place as well as they are easily de-mountable to be re-used. Connections are fitted and bolted rather than welded, as would be typical in a steel substructure. The structural system is engineered to withstand high wind loads and to shed snow.

These sub-structures are one hundred percent recyclable with no loss of quality when re-used in another product. According to the aluminum industry, which now has a partnership with the Department of Energy to reduce the energy consumption in the refining of aluminum: "In the last 50 years, the average amount of electricity needed to make a pound of aluminum has been slashed from 12 kilowatt hours to about 6 kilowatt hours. Recycling aluminum saves almost 95 percent of the energy needed to produce aluminum from its original source, bauxite ore."²

Aluminum is lighter than steel, to transport saving on overall shipping costs. Lighter freight weight, will mean less fuel consumption by the transporting systems and a reduction in carbon-dioxide emissions. Aluminum substructures are durable and long lasting; they won't corrode and can have a long life expectancy in any climate.

Architectural Membranes: Monolithic, Durable and Long Lasting

The architectural membrane of a tensioned membrane structure serves as both the walls and the roof of the exterior building system. All-weather outer membranes are delivered on-site in rolls, and winched along the frame from one side to the other using spacer bars, similar to the lofting of a sail. The membrane panels are tensioned across a spreader bar in the frame and insulation is added to the ribs as well as an interior membrane, tensioned into place by hydraulic machinery. Architectural membranes are stretched to a predetermined factor. It takes 1500psf to stretch the membrane using hydraulic rams. Manufacturers supply training and assistance to contractors as to the handling of the unique interior and exterior finish materials that are also part of the structural system.

When additional daylight is desired, a highly translucent daylight section can be chosen as a part of the membrane. The top section of the exterior and interior membranes is designed to insert a skylight along the apex of the spine of the building, providing an abundance of natural light for these high-ceiling structures.

According to the American Society of Civil Engineers (ASCE) Structural Engineering Institute's Standards on Tensile Membrane Structures, a fabric is defined as a two-dimensional cloth made up of yarns or slit tapes that may be impregnated with a matrix that binds them together. The yarns may be woven or laid, frequently coated or laminated. Membranes are defined as the flexible, coated, or laminated structural fabric of film that supports imposed loads and transmits them to the supporting structure.³ The membranes in a tensioned membrane structure carry only tension or shear in the plane of the membrane. Although tensioned membrane structures are engineered to have some movement in the frames, because the membranes are tensioned across spacer bars, there are no wear-points. When it is time to replace the membrane, sections can be replaced in segments without exposing any interior furnishings or fixtures. The strength or tensile properties of the finished coated membrane is controlled by its polyester base cloth. The PVC coatings are provided to protect from UV degradation of the fibers in the base cloth and to provide a weather barrier. An acrylic coating is specified to provide protection against Ultra-violet (UV) rays as well as airborne contaminants and pollution. For additional protection and a longer life cycle to UV and airborne contaminants, additional coatings such as Kynar, a PVDF film, can be added to the membrane which helps reduce the impact of weathering on the surface. An architectural membrane is a fabric but unlike a tent product that may be expected to have a short-term use, primarily as temporary shelter, engineered materials can be used as habitable buildings for many uses.

The next generation membrane coatings or films are top-finished and coated with Kynar an advanced form of polyvinylidene fluoride or PVDF. Kynar is a finish that architects have used for over forty years, on metal buildings and in high-end paint products. Applied as a film to membrane surfaces, Kynar provides superior resistance to staining, dirt and mildew growth as well as increased color retention, gloss and membrane life expectancies approaching 30 years. Membranes can be a solid color and printed with any logo, or symbol, or decorated with accent lines and patterns. They can be selected in multiple colors. Patterns and wave designs can be created using membranes.

Architectural membranes weigh from eighteen to thirty-two ounces per square yard, making them one of the lightest building envelope finish materials available to a design professional. The heavier materials can be specified for increased load requirements. Additional savings on fuel and emissions for transportation of this material are gained by using architectural membranes. An engineered membrane is not only the exterior surface of the building; it is also the finished surface of the interior walls and ceiling. Contractors and installers will require jobsite quality standards for handling these membranes to avoid scratches or blemishes on this interior wall and ceiling material.

Insulation: Airtight Membranes

Insulation provides comfort in both hot and cold climates. Insulation reduces the cost of climate control as well as absorbing sound for better acoustics. A comprehensive insulation package for a tensioned membrane structure includes vapor barriers, thermal breaks and a tensioned, finished interior liner. Additionally, membranes are designed to have low air and vapor permeance.

A structure with a lattice beam frame that is merely filled with insulation can leave unvented dead air spaces, creating the opportunity for the spread of mold, mildew and fire. In any building, holes in the insulation can dramatically reduce its performance and multiple layers of insulation may merely add to dead air spaces between each layer, negating much of the insulation value. Retaining the insulation within a cavity is crucial and in some membrane structures, insulation has been known to slide down the roof and bunch at the base of the wall.

Designed to accept a sandwich of fiberglass batting, insulation in a tensioned membrane structure, as in any green building, can be specified with fifty-five percent recycled postconsumer glass. Every day, over 120 tons of recycled glass, normally bound for the landfill, is melted down and utilized in the manufacturing of the insulation. In addition, an acrylic resin is substituted in the manufacturing process to ensure no phenol-formaldehyde or ammonia emissions are created.

According to the EPA, "Formaldehyde, a colorless, pungent-smelling gas, can cause watery eyes, burning sensations in the eyes and throat, nausea, and difficulty in breathing in some humans exposed at elevated levels (above 0.1 parts per million). It has also been shown to cause cancer in animals and may cause cancer in humans."⁴ The EPA has been working to reduce the use of formaldehyde in building products as research continues to mount as to the hazards of formaldehyde in insulation products.

Most environmental rating systems, such as Green Globes, USGBC LEED®, BREEAM, and the California High Performance Standard, give credit for indoor air quality and materials that prevent volatile organic compounds from being off-gassed into buildings by building products. Formaldehyde-free insulation improves air quality, and adds to the evaluation of a green building.

Engineering: Daylight and Views

As previously mentioned, these structures are engineered to receive optional skylights that straddle the spine of the building. Skylights provide a highly translucent interior glow to the finished building with relatively minimal heat loss. In addition, energy-efficient windows and doors can be added to these structures to provide direct daylight and views. Connections to other buildings, new lobbies and entries are all potential daylighting opportunities for the design professional.

Ravenna Golf Club needed a banquet and tournament facility to increase revenue and considered erecting a conventional tent building. After seeing the very latest insulation and glazing wall systems provided by tensioned membrane structures, the club chose an alternative that met the aesthetics they required in a permanent structure.

Environmental Stewardship: Global and Local Ratings

The Environmental Assessment Method for Buildings around the World

When considering environmental stewardship, often a designer will turn to a rating system to keep track of the environmental performance of a building. New to North America, as permanent building structures, in England tensioned membrane structures have received high ratings through BREEAM-The Environmental Assessment Method for Buildings around the World. BREEAM, created in 1990 is one of the first green building rating systems in the world. There are different routes for certification and third-party assessments are performed for design and procurement, for new and renovated buildings, post construction and management and operation.

The BREEAM rating system includes sections on management, health and wellbeing, energy, transport, water, material and waste, land use and ecology, and pollution. Credits are awarded in each of the areas according to performance and the credits are weighted to produce a single score. The building is rated on a scale of: pass, good, very good, excellent or outstanding and a certificate is awarded to the development.⁵ As part of the BREEAM energy rating system and legislated by English law, all new buildings and major refurbishments must meet minimum standards for energy performance. These buildings now need an Energy Performance Certificate (EPC) whenever they are sold or leased. The EPC is based on the construction performance, as well as the systems (lights, HVAC) performance of a building.

When Collingwood College built their new sports hall in Camberley, Surrey, UK, their tensioned membrane structure received an EPC rating of 35. As compared to other newly built buildings, this sports hall is 10 points more efficient and 45 points more efficient than the typical building of the existing building stock. In addition, the hall passed a required air leakage test exceeding building code standards by approximately 75 percent.

Another tensioned membrane sports hall, HMP Littlehey II, sports hall in Perry, Huntington, Cambridgeshire, received a 73.05 percent Four Star Excellent, BREEAM Certification Rating. This is the second highest rating achievable in the BREEAM system for environmental performance.

U.S. Green Building Council-LEED^®

Deborah A. Snow, AIA, LEED AP, Project Manager and Joel McCreary, AIA, LEED AP, recently completed Silver LEED certification and construction of a tensioned membrane dining hall, gymnasium and classroom facility for the South Carolina Criminal Justice Academy Village.

The project included the master planning and design of several buildings for this campus and involved the use of existing driveways and campus infrastructure. Phase one included a tensioned membrane structure and project sitework. The structures are required to meet LEED-Silver requirements as per state mandates. The project is approximately 32,000 square feet of enclosed area housed in three tensioned membrane structures. All structures were classified as Type IIB, with an aluminum frame, insulating skin and slab on grade. Phase two will include the conventional construction for a four-story dormitory and central energy facility. Both phases are currently under construction.

Architect Joel McCreary spoke to the ease of installation and the difference in how he and his partner visualized this building. The frames were engineered and manufactured like "works of art." The interior and exterior of the structure are also the finish materials of the building and require a different understanding of how to handle the materials on the jobsite. According to McCreary, "Everything is a finish and all is exposed to view." He also reports that an engineered monolithic structure is very different from a temporary, utility membrane building-in their durability, warranties, quality assurances, structural capabilities and usability as permanent and habitable structures.

Superior Energy Efficiency Designed to Climate

As a monolithic surface, tensioned membrane structures are airtight and therefore, provide numerous advantages as an energy-efficient building envelope. Insulating a building envelope requires that the contractor reduce leaks, and provide insulation values that are consistent across the skin of the building. A monolithic structure with an insulation sandwich across all of its structure, meets both of these objectives. ENERGY STAR recommends insulation values for buildings that are constructed in all climates in the United States.

In a tensioned membrane structure, insulation is placed between the ribs of the aluminum frame. There is a thermal raised thermal cap fitted to the frame on both the interior and exterior of the frame to complete a thermal break and integrate the thermal envelope.

With insulating values of up to R-30, the insulation along with the membrane structure, meets or exceeds ENERGY STAR recommendations. The 2006 International Energy Conservation Code (IECC) is the new model energy code for conditioned commercial spaces. Major changes include more stringent requirements for envelope construction, particularly in cold climates as well as the requirements for the percentage of glazing in a building. Many tensioned membrane structures have been designed and tested to meet the 2006 IECC and professionals should require verification of code compliance.

Preventing Construction Waste

According to a white paper from the USGBC, the impact of construction and demolition debris causes substantial damage to the environment. "More than 135 million tons of debris from construction sites are brought to U.S. landfills every year, making it the single largest source in the waste stream. Figures developed by the U.S. EPA are helpful to the building owners, designers and contractors in understanding the magnitude of C&D (construction and demolition) waste. In commercial construction, a typical new building generates an average of 3.9 pounds of waste per square foot of building area. To put this in perspective, a new building of 50,000 square feet (a typical college residence hall or mid-size suburban office building) will produce 195,000 pounds, or almost 100 tons of waste."⁶

Membrane-covered frames reduce construction waste by design. The components of these structures arrive at the site pre-fabricated and ready to be assembled with little to no packaging.

Meeting and Exceeding Building Codes

A tensioned membrane-covered frame structure is defined in Chapter 2 in the definition section of the 2015 International Building Code (IBC) as a “non-pressurized building wherein the structure is composed of a rigid framework to support a tensioned membrane which provides the weather barrier.” Chapter 31 section 3102 “Membrane Structures” of the IBC provides guidelines for structures erected for 180 days or longer. Structures erected for a shorter period of time shall comply with the International Fire Code. Section 3102.3 defines the types of construction as either Type IIB or Type V construction.

Even though the frame of an aluminum structure can be classified as non-combustible, the approved membrane or wall section is considered non-rated. Membranes as described in Section 3102.3.1 of the IBC need to meet the fire propagation performance criteria, as appropriate, of the National Fire Protection Association NFPA 701.

Manufacturers must supply supporting documentation and independent lab testing to verify that outer and inner architectural membranes meet the requirements of the International Building Code and pass the following fire test protocols; NFPA 701, ASTM-E-84, California State Fire Marshall, and the Canadian Standard ULC-S-109 and ULC-S-102. Some of the other requirements that must be met in an architectural fabric membrane include the requirements of Section 803.1 with a Class A rating, that has a flame spread of 25 or less and a smoked developed index of 450 or less as per the testing requirements of ASTM-E-84.

The membrane portion of the structure is to be designed as per the ASCE Standard 55 “Tensile Membrane Structures." "This standard provides minimum criteria for the design and performance of membrane-covered cable and rigid membrane structures, including frame structures, collectively known as tensile membrane structures, including permanent and temporary structures as defined herein. The requirements of this standard shall apply whether the tensile membrane structure is independent of or attached to another structure.”

A two-pound per square foot uniformly balanced utility load has been found to be adequate to meet typical loading requirements on a tensioned membrane structure. The design and engineering should allow for the appropriate roof load that includes the hanging of lights, sprinklers, HVAC equipment, ceiling grids, security systems, etc. The design professional can increase the dead load (and wind ratings) by requiring the placement of structural arches closer together. Conversely, moving structural members further apart can and will reduce loading and costs. Architects should be careful of competitive bids where the dead load is not specified or considered as part of the bid package as it can affect the actual cost of the project.

Consulting engineers provided by the manufacturer will review major loads, which are to be suspended from the structure to identify any problem areas. The design professional will need to provide all details, drawings, and weights associated with the utility loads as well as provide the structural adequacy of the connection details.

Tensioned membrane structures are designed to flex in high wind conditions. The membrane systems for tensioned membrane structures have been designed, tested and approved for use in hurricane debris zones. In 2005, with maximum sustained wind gusts up to 175 miles per hour, Hurricane Katrina ripped through New Orleans and much of the South. Faith Temple Ministries in Buras, Louisiana, was engineered to meet the International Building Code to withstand 100 mph winds. After two days of high winds, this church building sustained only minor damages and was one of the few buildings left standing. The membranes that were damaged were quickly replaced. To withstand high winds, all connections to the structure should be flexible to account for this movement. Self-tapping screw connections to the structure are not permitted and utilities cannot be attached to the structural spreaders. Attachment to the structure must only be to the beams using the bolt chase on the bottom flange of the beam for insulated structures. The weight of the mechanical systems, sprinklers or lighting will determine the weight of the brackets to meet loading requirements.

Connections attached through the bolt chase should have a minimum spacing of 3'-0". No single attachment is to exceed 300 pounds. Heavier items can be load shared between different points of the adjacent arches. There are many different beam clamps and attachment methods available from various companies. The manufacturer may also provide specific types of hanging brackets for their structural system.

Increased Fire Safety

Redundancy Prevents Building Collapse

There are many design redundancies in a membrane-covered frame that increase the overall safety of the structure. These include structural redundancy, and easy insertion of sprinkler and alarm systems.

The structural function of the membrane is to transfer environmental forces to the aluminum support frame. Although the structure is designed without benefit of the membrane, the membrane provides a redundant load path for stability of the structural system. The system is stable without the membrane. With the membrane, damage to one or more arches or fabric panels will not reduce the stability or load carrying capacity of the structure.

In the case of a fire several conditions could occur. If all the membrane is destroyed, the frame should be capable of supporting its own weight and a utility load allowance. In this situation, the effect of the environmental loads on the structure is minimal since the membrane is not there to transfer the environmental loads to the aluminum support frame. If the fire is in a localized area, and one of the load carrying arches is damaged due to a fire, the support system should be designed to permit load sharing of the imposed loads with the adjacent arches. If there is a fire in a in a localized area, and a panel of the membrane is damaged the effect on the capacity of the support system is minimal.

An internal fire source can generate sufficient heat to damage the architectural membrane. An opening in the membrane will allow the venting of smoke and heat without compromising the structure of the whole building and avoids the collapse of the building on occupants.

Exposed Fire Suppression Systems

In a tensioned membrane structure, fire suppression systems are exposed. In fact, one of the qualities of a permanent, habitable membrane-covered structure as opposed to a temporary building is the quality assurance that the building has been engineered to support required equipment. Conventional sprinkler and fire alarm systems can be easily installed and maintained. Design professionals may also choose to add quick response, high flow or additional sprinkler heads in lobbies or areas with high occupancy. Interior standpipes can also be installed as part of an overall sprinkler and fire safety design strategy.

Fire Fighting: Easy Access

A membrane-covered structure can be easily penetrated by firefighting personnel at any given point on the structure. Firefighters can fight the fire from the perimeter of the structure and penetrate the structure as needed. When a membrane is exposed to fire, it melts but does not spread the fire. Fire will not travel across the system causing more fire damage to the structure.

Due to the high vaulted ceilings in these structures, a smoke reservoir is created in the high roof areas, leaving the floor clear of smoke, making it easier for occupants to safely exit the structure and for fire fighters to locate and extinguish the fire. Roof monitors with dampers can be installed to remove smoke as it collects in these high roofs (smoke reservoir) areas.

Safety and Security

Clients may be concerned by the ephemeral appearance of a tensioned membrane structure and the possible vandalism from piercing the envelope. Tensioned membrane structures have been sighted in some of the most populated regions of North America and there have been virtually no reports of vandalism or break-ins. The architectural membrane is made of a rip stop construction that prevents tearing or puncturing of the membrane. Most graffiti can be easily removed from the coated membrane surfaces. Used as prison dormitories, the buildings are as secure as most conventional building types.

The Bottom Line

Design professionals have many choices to make for their clients that include a multitude of options, from speed of construction, to the delivery of a "wow" factor on a limited budget. As architect David Simpson states, "After four years, the building still works well for the client." He continues to be amazed that a building that looks so large on the inside seems much smaller on the outside and fits the scale of the community so well.

Next generation membranes like Kynar and comprehensive insulation packages are what has propelled these type of structures into "lifetime" building markets after 30 years. Similar to re-roofing a conventional building, a new membrane can be installed to provide another 30-year cycle.

As an alternative to large box buildings, or smaller buildings, used as clubhouses, restaurants, or additions, the choice of these vaulted, and expressive, tensioned membrane structures makes design sense. Interiors can be configured independent of the overall structure, allowing for great flexibility for use, renovations and re-use. They can be constructed for approximately 35 to 50 percent less than the cost of a conventional structure, with similar aesthetic qualities and high-rated performance requirements.

Tensioned membrane structures are eligible for many green building rating systems particularly for their high performance values. These structures can be a sustainable choice as an addition to the design professional's building portfolio.

Celeste Allen Novak AIA, LEED AP is an architect specializing in sustainable design and planning in Ann Arbor, Michigan.

Endnotes

1 http://www.wbdg.org/design/env_introduction.php 2 http://www.aluminum.org/AM/Template.cfm?Section=Overview& Template=/CM/HTMLDisplay.cfm&ContentID=27135 3 http://books.google.com/books?id=bbg-1DkatJQC&pg=PA1&lpg= PA1&dq=ASCE+standard+code+definitions+membranes&source= bl&ots=vJ08r4YcKZ&sig=XUvdJBku4z59t_w5StOGJe9wY4w&hl =en&ei=rhHUTL-_JJOhnQe09_WPBg&sa=X&oi=book_result&ct=result&resnum= 2&ved=0CBcQ6AEwAQ#v=onepage&q&f=false 4 http://www.epa.gov/iaq/formalde.html 5 http://www.breeam.com/index.jsp 6 http://www.modular.org/marketing/documents/USGBC_ WhitePaper_PlanningConstructionWasteReduction.pdf 7 http://www2.iccsafe.org/states/newjersey/NJ_Building/ PDFs/NJ_Bldg_Chapter3.Pdf

Sprung Structures engineered high-performance, tensioned membrane structures are designed to provide innovative, cost-effective building solutions for interim and permanent applications. www.sprung.com