by by Heather Collins — One functional and affordable component of sustainable building design involves specifying a solar shading system as a key element of the exterior building envelope. Exterior solar shading is essential to building performance. When the appropriate shading material is specified, it allows for optimum daylight and views and a subsequent decrease in solar heat gain. Shading systems also diminish the amount of natural light that enters a building during the day while reducing the spill of light pollution from the building interior and exterior light sources at night. This in turn leads to a reduction in energy consumption and a healthier, more productive environment with improved indoor air quality.
Solar shading devices can also contribute to United States Green Building Council Leadership in Energy and Environmental Design (LEED®) certification. Specifically, solar shading systems can earn credits in many of the LEED New Construction categories.
Shading with metal fabric
When selecting components for the exterior building envelope, an informed decision that takes the life-cycle performance, sustainable attributes, functionality and aesthetics of the proposed material into account is crucial.
Sustainable building materials like stainless steel mesh more than meet these stringent standards. Woven metal mesh—manufactured from recycled materials—maintains a very long lifecycle, is inherently resistant to scratches, denting and corrosion and is virtually maintenance-free. The attachment hardware used to affix metal fabric panels to a structure is also readily recyclable and can be fabricated from recycled materials. Even the manufacturing process for woven stainless steel fabric—a cold forming process—creates a lower environmental impact than the process for alternative heat treated products.
Designing with metal fabric can also reduce building costs and because of its light weight and flexible design, uses less material. This produces significantly less waste than most traditional building materials. Metal mesh also requires minimal structural support, reducing the cost of materials and labor. Shading supplied by a metal fabric system is most effective when the mesh is installed over glass, which enhances the shading effect by reducing the light entering a building. Metal fabric additionally reduces heating, ventilation and air conditioning requirements while offering an elegant, contemporary aesthetic appeal.
Like traditional shading materials, woven metal fabric significantly reduces solar glare, light pollution from electric night lighting and solar heat gain. However, unlike conventional shading materials, architectural metal fabric also promotes airflow and building security. It is designed to meet an array of opacity, shading and heat reduction requirements.
Aesthetically, architectural mesh can provide a more sophisticated, refined or edgy look compared to traditional louvers, canopies, fabric curtains or other products commonly used as shading devices. Architectural mesh is also unique in that its interaction with light varies based on the weave of the pattern specified. Closed, tight weaves can block illumination completely, while open patterns allow varying degrees of light to pass through. Each mesh pattern also lends a different element of aesthetic interest.
Overall, architectural woven metal fabric adds a dynamic, sophisticated element to a structure while providing maximum solar shading and energy saving benefits.
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| The University of Washington Medicine Lake Union Building in Seattle, Wash., to be completed in March 2008, will feature a solar mesh system designed to control solar heat gain and reduce building energy costs, while adding an aesthetically pleasing element to the building envelope. |
Reducing solar heat gain with architectural mesh
The University of Washington, Seattle, Wash., chose to specify a metal fabric system from Cambridge Architectural—a North American manufacturer of architectural mesh systems—as an exterior shading device for the Medicine Lake Union Building. The major medical research laboratory structure required a shading system that would control solar heat gain while still permitting natural daylight to flow through the facility.
Cambridge Architectural was able to provide Perkins & Will—the architect responsible for the design of the facility—with a study that determined energy reduction statistics for a customized metal fabric pattern to meet their specific opacity requirements. This was a contributing factor in the firm’s decision to specify architectural mesh as a solar shading device.
Cambridge maintains the ability to calculate potential temperature reduction for the shaded space created by the installation of its metal fabric, along with possible energy savings resulting from the installation of the metal fabric product. The temperature reduction calculation is the result of a recent analysis that tested the solar heating properties of various types of metal fabric weaves placed over clear glass varying in thickness.
Testing the solar heating properties
A U.S. Department of Energy model examined the energy and financial impact from the installation of a mesh screen with 50 percent coverage onto a 30-story commercial office building with clear, double-glazed windows. Results from the study show a considerable decrease in energy costs. Specifically, the study predicts a savings of US$94,000 annually for the commercial building that was analyzed, due to the addition of the metal fabric screen.
The study is significant in that it provides concrete evidence of the solar shield functionality of Cambridge metal fabric, demonstrating its ability to dramatically reduce building energy costs.
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| Cedar City Library in Cedar City, Utah, features a custom variation of Cambridge Architectural’s Grid, Ridge and Bead woven metal products. The metal fabric provides an aesthetically pleasing method of solar shading. |
In some cases, the study may serve as a guide for an architect considering the use of metal fabric. In other instances the information can be used to tailor a study to determine the potential solar heat gain reduction capabilities for a specific building project, like the Medicine Lake Union Building.
“When we first began designing the exterior skin of the Medicine Lake Union project, we knew we wanted to implement a shading system to control the amount of solar heat gain entering the building from the western and southern facades,” explains Andrew Clinch, University of Washington Medicine Lake Union Building project architect and designer. “After weighing our options, we chose a woven metal fabric due to its texture and transparency.”
The metal fabric chosen for the Medicine Lake Union Building will be mounted with a modified tension attachment method, which uses elegant, custom cut apertures that receive the metal fabric ends in tubing integrated into a bracket and structural support design for a clean, contemporary look.
“We chose Cambridge Architectural’s metal fabric pattern because we were able to customize the exact opacity to meet our energy requirements,” continues Clinch. “The metal fabric design turned out to be exactly what we were looking for—a lightweight exterior shading application that allowed natural light to fill in the lab spaces while simultaneously controlling solar heat gain and reducing our energy costs.”
Upon completion in March 2008, the facility will benefit from the solar shading properties of the exterior installed metal fabric system. The mesh will additionally lend a modern aesthetic element to the building envelope.
Choosing a metal fabric manufacturer
When selecting an architectural metal fabric manufacturer, look for one that is experienced in fabricating mesh systems for solar control purposes and maintains the ability to provide energy saving calculations for the proposed installation of the metal fabric.
Additionally, manufacturers that are USGBC members can promote architectural mesh systems that will meet the most current LEED requirements. A manufacturer that is available to provide consultations on a project-by-project basis can also maximize the integration of mesh with other products, which can be a requirement for certain LEED credits. Above all, look for a responsible building manufacturer that can provide specific product and manufacturing solutions that will meet your solar shading needs. FMJ
About the author
Heather Collins is director of marketing for Cambridge Architectural, the world’s most experienced and only full-service provider of functional and visually intriguing metal fabric systems for interior and exterior building applications. Collins boasts more than 13 years of senior management leadership in marketing, corporate sales and business development. For more information visit www.cambridgearchitectural.com.