Strategies for More Sustainable Exterior Solutions  

There is beginning to be a rich consensus that it is better to build within the framework of environmental design rather than to ignore the living systems of our planet. Design stewardship means that professionals are now creating living habitats, buildings that breathe, environments that protect water resources and capture daylighting.

In the 1990s as a response to the emerging knowledge that buildings were wasting natural resources and energy, the AIA Committee on the Environment provided a list of measures to be used as metrics when selecting building systems. This article will describe some of the ways in which manufacturers are meeting the challenges posed by the AIA as well as the U.S. Green Building Council, to provide products that are beneficial to the environment.

Consider Building a Living Environment

"Managing the organic environment can be a challenge to the designer as well as the community that is required to nurture its growth patterns," says Paul Bambauer, President of IRONSMITH. Growing living screened façades, planting trees downtown or creating garden paving systems may require the integration of natural materials with other building systems, or at a minimum, the understanding of how to manage or design for a changing, living environment. Moreover, according to James Sable at greenscreen®, designing for nature "is more efficient building energy performance as well as human well-being. It is the means to embrace nature rather than protect from nature − by design. Natural spaces are designed to welcome humans and increase the daily experience of human life."

Incorporating natural systems also includes low impact design for water conservation as well as the high impact designs for dark sky lighting and daylight harnessing. As Jim Engelke, ASLA, LEED AP, from SOIL RETENTION states, "It's important to recharge our aquifers because the scope of our development has increased the amount of impervious surfaces and thus reduced their ability to recharge themselves. Whether from rooftops or roadways, water is conveyed off into storm drains to rivers and oceans, but the earth is not receiving its fair share."

At the National Wildlife Federation Headquarters in Reston, Virginia, a living habitat is incorporated into the building façade. Photo courtesy of James Sable / greenscreen®

 

Controlling lighting at night, a "dark sky" practice, means that the design professional can provide both a safe nighttime environment without prohibiting a view of the night sky and stars to the surrounding neighborhood. According to April Ruedaflores, Marketing Manager of Kim Lighting, "Designers should be able to harness light and place it where it is needed."

Phoenix Civic Space Park features paver grates with unfinished aluminum trim rings to provide stormwater management. Photo courtesy of Carol Brennan Associates

When using glass flooring to provide daylight harvesting, Tim Czechowski of Jockimo Inc. remarks, "There is an old saying, 'knowledge is power,' and that in order to choose the very best glass flooring and glass treads/steps, one must learn as much information as possible about the product. Glass flooring is a liability product and in turn, using the safest possible glass flooring solution possible is critical when specifying it for projects."

In the response to new market demands for materials that are safe for the environment, new products are now available that provide even more sustainability. As an example, a thin exterior surfacing system, with high thermal properties is made from cement rather than a petroleum product. John Garuti Jr. of Formulated Solutions LLC notes that it is now possible for chemistry to "provide the means to redefine a wall system, combining durability, flexibility, increased permeability and hydrophobicity − all within a zero-VOC cementitious system."

Codes and standards are growing green, merging and creating new regulations. "Specifying systems that exceed code will help meet the new initiatives of the Department of Energy which is encouraging the U.S. construction market to build energy efficient buildings. The commercial fenestration market has improved over 50 percent in energy performance in the last 5 to 10 years and continues to focus on recycled content, life cycle performance and waste stream avoidance to bring the industry to new heights of sustainable building." says Mike Turner, Vice President of Marketing for YKK AP America Inc.

Fixtures that provide dark sky lighting can have a dark sky seal of approval. Photo courtesy of Kim Lighting

This article will review a number of strategies for more sustainable exteriors. The featured exterior products are highlighted with five of the "Ten measures of Sustainable Design" developed by the AIA Committee on the Environment. In general, many of these products meet more of these measures than are listed.¹

Structural glass flooring can be used to bridge across nature, allowing natural light to spill into spaces below. Photo courtesy of Jockimo Inc.

 

The cementitious finish allows the wall to breathe and increases its performance in wall systems. Image courtesy of Formulated Solutions LLC

Example of a corner detail for a building sunshade. Photo courtesy of YKK AP America Inc.

 

STRATEGY #1: Measure 4: Bioclimatic Design - building living habitats
Sustainable design conserves resources and maximizes comfort through design adaptations to site specific and regional climate conditions.

The Vertical Wall −designing for living habitats and energy efficiency

The headquarters of the National Wildlife Federation is nestled into a wildlife area. Designed holistically, the massive planted screen wall on the south facing exposure is both a natural habitat as well as a mechanical system that reduces heat gain on the wall's exterior facade. Indigenous deciduous vines were established to provide leafy shade in the summer and streaming sunlight in the winter. The three dimensional metal grid was engineered for the climate and cooling for the southern exposure of the building.

Providing a living green façade on, or adjacent to, buildings is beneficial for two main reasons. First, they are systems that can increase the performance of the mechanical system by providing both shade and natural cooling. When planted screens shelter rooftop mechanical systems or building facades, they protect the units from heat island gains and hot rooftop areas. Air that is tempered around the mechanical system reduces the cooling load; less energy is required to cool the ambient air to room temperature. Secondly, planted screens create a transition zone that incorporates nature into architecture when used to shade a building façade. Modular, stacking green wall systems should be rigid, light weight and engineered to meet required spans and design loads.

Planted green walls should have structural capability and can be attached at the perimeter of a wall system. Systems are available that can span from 8 feet to 12 feet and that can resist a 90 mph wind load. Some important criteria for professionals to consider include:

• Remember that green wall panels are designing with a living system that changes as it grows.
• Think about the importance of materials used to create the metal grids and choose systems that use a high percentage of recycled steel as part of a more carbon neutral design strategy.
• Review plant materials with a landscape architect or horticulturist. Living systems can take a while to mature and depending on the climate zone or urban environment should be chosen for adaptability and longevity.
• Account for the water, nutrient and drainage conditions that will change as the plant grows.
• Don't underestimate the time of growth, and provide information to the building owner on the reasons for investing in the maintenance of this living system.

Photo at installation showing the gap between the future green façade and the building.	A similar view of the National Wildlife Headquarters after plant growth has created a living environment away from the building.

 

One of the latest trends in using green walls is to create vertical gardens in multi-storied buildings. When designing at elevated surfaces, the professional needs to design this system as a series of elevated planters, understanding the solar orientation and wind loads as well as providing a means to convey water to raised floor platforms. Some of the future advances in green grid façade technologies will be the incorporation of gray water systems to efficiently support the building's long term integration of the plant areas, providing nutrients to the plants as well as water purification.

Vertical planting systems are also an important opportunity to contribute to community habitat planting. As shown in studies like Lloyd Crossing, by Mithun Architects, calculations can be made that reestablish native habitat, species, birds and plants to maintain a sense of place, expanding from the familiar horizontal approach to the building site to include its vertical wall surfaces. Planted green wall systems can provide the place for bird songs, providing an acoustic buffer from the street.

From a planning or community perspective, cities are often requiring more sensitivity toward the creation of place. Parking structures and large blank walls on commercial buildings can become assets rather than eyesores by the placement of vertical green walls. Using planted vertical green walls can assist the professional in obtaining credits in virtually every category of LEED® V3 including site development, water efficiency, regional credits, energy efficiency, recycled content and innovation.

Planted green walls are an innovative way to make an aesthetically pleasing and natural habitat for the entire biology of the building site and the neighborhood of a locale in a new built facility.

STRATEGY #2: MEASURE 6: Water Cycle
Sustainable design conserves water and protects and improves water quality.

The Horizontal Plane −designing for living habitats and water conservation

Low growing oregano, marjoram and thyme, bring fragrance when grown in a permeable, flexible and plantable concrete paving system. Using permeable, flexible, planted paving systems provides an opportunity to recharge the local aquifers, the source of drinking water in all areas of the country. These systems can assist with federal requirements for storm water management, reduce heat island effects, and in some communities, increase the proposed building footprint based on additional detention and infiltration areas per city ordinances and codes.

A section of a typical planted cement paving system Drawing courtesy of SOIL RETENTION

 

Most plantable concrete paving systems are cellular. One of the newest products is made from pre-cast concrete, cast around a flexible mesh. Installed correctly, this system will provide a living horizontal plane in a surface that will provide stormwater management as well as an innovative green parking garden. Plantable concrete paving systems provide an opportunity for the continuation of connecting living habitats across a site's infrastructure.

These systems can be as thin as one and one half inches thick, and be laid as a two foot by two foot precast concrete mat. The surface below the mat is prepared with a base of crushed rock, between three and four inches for residential applications and up to 12 inches for commercial projects. Over the aggregate a structured soil or root zone is placed, comprised of 80 percent sand and 20 percent organic materials. The mat is set over this engineered soil surface in grids that are fitted and aligned together. Because the mat layer is thin and set on top of the root zone, the plantings share irrigation moisture between all of the cells. In contrast, many individual cellular pavers are deeper and tend to constrict proper irrigation moisture from transferring cell to cell. In the Construction Specification Institute Master spec Section 32 12 43 (1997 Section 02795), permeable, plantable paving systems have their own category and performance standards.

The flexible concrete paving system is designed to expand and contract with the freeze thaw cycle, has low moisture content, and can be specified in numerous colors to match the designer's palette. Beside fragrant herbs, landscape designers can specify other low growing plants, silvery grasses, new hybrid drought tolerant buffalo grass or even just an aggregate or bark infill. After planting, the horizontal surface can be mowed as it grows or in snowy climates, with proper height adjustments can be scraped by snow plows with teflon runners and squeegee blades. In icy weather, planted driveways provide, safe walkways as the concrete warmed by the sun, transfers heat through the soil providing ice melt that infiltrates into the ground below instead of ponding.

Plantable paving met city ordinances and for LEED® requirements as well as provided additional green parking for the Red Bull headquarters in Santa Monica, California. Photo courtesy of SOIL RETENTION

The new Red Bull headquarters in Santa Monica, California, designed for LEED® platinum, by architect Yi Shen with HLW International, used permeable paving for storm management.

Plantable concrete paving systems can assist with LEED® credits in numerous ways. In site development categories, they protect and restore habitats, maximize open space and provide stormwater design credits for quality and erosion control. They assist with the reduction of heat island effects for non-roof categories and some systems can also be used for green roofs. These paving systems can be used as a permeable water filter that can collect water for re-use, and planted with water efficient landscaping for more water savings on the site. They can contribute to an innovation credit as part of an integrated strategy for design and site planning.

Tests have been performed on these systems that show that they maintain their stability, even under the weight of large vehicles, providing proof for city fire departments that this product meets requirements for deflection standards. This product should be installed as a system. A common mistake is to believe that the substructure is not needed in order to grow a paved field of grass. These concrete mats can have up to 45 percent replacement of portland cement with fly ash, providing assistance with LEED® V3 credits for the highest levels of post-consumer recycled content. Many of these systems are manufactured throughout the United Sates and can also assist with credits for regional materials.

As an added bonus, planted concrete paving systems are easy to install and can increase buildable footprints by reducing detention requirements. Last year, six or seven church volunteers in Florida installed over 5,000 sf of pavers a day for their new planted driveway area. Local planning and building departments are requiring more stormwater onsite retention to comply with the federal National Pollutant Discharge Elimination System (NPDESII) statute. In response, architects and owners are providing alternative parking areas that also double as infiltration basins.

Planted concrete paving systems provide professionals with many opportunities for LEED® credits including those for site development, stormwater design, heat island effect, water efficient landscaping and recycled content not to mention the many ways to design with these systems for innovation credits. Professionals and homeowners are planting natural areas in constructed parking lots and driveways to increase green space. Installing planted driveway paving systems can contribute to the reduction of the heat island effect in urban areas, create more opportunities for storm water detention, and help the environment with an ecological alternative to solid asphalt or concrete paving.

STRATEGY #3: MEASURE 3: Land Use & Site Ecology
Sustainable design protects and benefits ecosystems, watersheds, and wildlife habitat in the presence of human development.

Trees − managing pedestrian shade and increasing energy efficiency

One tree makes up the CO2 produced in the manufacturing process for some tree grates in less than three years. After that, trees continue to benefit the environment by increasing air quality and decreasing the urban heat island effect.² Tree grates can be made from one hundred percent recycled iron extracted from old vehicles and appliances and they are also one hundred percent recyclable. That's good for the environment and good for designers who care about the carbon footprint of materials.

Like planted driveway pavers, the success of a tree planting system depends on the composition of the soil, the type of tree and the engineered base. Trees are a living system. They need to be maintained, watered, and nourished throughout their life span and expected growth pattern. Planting trees and providing stormwater detention in urban areas, benefits the ecosystem, watersheds and wildlife habitat.

Phoenix Civic Space Park features aluminum trench grates in a custom frame for a fountain, and trench grates along a water wall to provide a space for play and cooling in this hot urban setting. Photo courtesy of Carol Brennan Associates

 

Tree grates and stormwater trench drains should be durable providing long lasting enclosures that can last over forty years. These components need to weather in the harshest of urban environments, withstand salt spray, snow plows, traffic, the grit of urban rainfalls as well as the hot humidity of summer. They are most durable when specified in unfinished iron that weathers to a burnished industrial surface or unfinished aluminum that can withstand harsh marine environments. When used in an urban setting they can be installed with pilfer proof tie downs, to prevent theft.

As with vertical walls and planted paving systems, designing for an organic environment means educating the community or the client in the management of the system. Tree grates are sized by the growth patterns of a tree, and can "grow" as the tree matures with break panels that are adjusted throughout the lifespan of the tree. Design flexibility is important and so is the branding of the environment as tree grates and storm trenches can be imprinted with the name of the city, a facility or even an amusement park.

Two views showing street tree grate retrofits for existing trees in City Heights Center − San Diego, CA

 

When City Heights decided to retrofit their streets, they were able to do so without cutting down the existing trees at the curb's edge. By working around the existing tree roots, arborists were able to engineer constructed soils to maintain a planting channel or link between the trees so that they can share moisture content and grow as a natural system. As shown, a section of a tree paver grate demonstrates that the tree can be protected at its base by tree grates with openings to provide irrigation and impact damage from pedestrians and their pets.

The Colorado Tree Study provides a comprehensive list of the benefits of trees in urban areas.³ According to this study, trees help with carbon sequestration, reduce pollutants, protect our water, save energy, extend the life of paved surfaces by blocking UV rays, increase traffic safety, improve economic sustainability and affect consumer perceptions and behaviors. Providing trees along a neighborhood street applies to many LEED® categories, particularly in the new LEED® s for Neighborhood Development.

STRATEGY #4: MEASURE 8: Materials & Construction
Sustainable design includes the informed selection of materials and products to reduce product-cycle environmental impacts, improve performance, and optimize occupant health and comfort.

Exterior walls −curtain walls and sun shades

Harnessing sunlight requires integrated thinking. Designers must know the climate they are designing for, the orientation of the building and the angle of the sun at various times of the year, as well as educate building owners, operators and occupants. In addition, lowering the energy requirements of a building will also compensate for the energy lost through even high end insulating windows. Numerous studies show that humans are healthier and happier when they have adequate amounts of daylight and views, but in many climates, this can place an expensive burden on the thermal flow of the building.

Manufacturers are engineering new aluminum window systems and facades with high performing thermal properties. New façades can also incorporate thermal breaks into the anchors that attach exterior sunshade devices. Exterior sunshades control the sunlight entering a building by blocking the high sun angles in the hottest part of the year and allowing sunshine to enter the building when it is cold. A passive strategy that reduces the mechanical load on the building, sunshades are effective because they block heat rays from striking the building, reduce solar heat gain and thereby help lower energy consumption.

Sunshades also improve visual comfort for building occupants, reducing glare as well as adding to the overall aesthetic of the building façade. Integrating sunshades into aluminum curtain walls can be challenging. Adding sunshades to a structural system can often cause thermal bridging creating cold points that compromise the energy efficiency and condensation resistance of the system. Energy-efficient aluminum frames and sunshades are now being engineered to stop thermal bridging.

Sunshade with thermal anchor as part of a façade system Photo courtesy of YKK AP America Inc.

 

When choosing an aluminum storefront, curtain wall, or its many components, architects should minimize the energy flow between the interior and the exterior by incorporating thermal barriers into the cladding systems. This can be done by specifying high performance systems that have good insulating properties (also knows as U-values). When selecting a thermal barrier the lower the thermal conductivity of the material the better the system's performance. A common error when integrating building envelope components is "short circuiting" the insulating properties of the system. An example of this is placing a framing system directly on the slab making the thermal barrier ineffective. Shimming the system from the base of the slab with low conducting materials, like high-impact shims, isolates the systems and improves the thermal performance of the building. Other components like sun shade devices must also be integrated with the curtain-wall or building system to prevent thermal bridging.

According to Mike Turner, Vice President of YKK AP America Inc., "In the past, architects could meet many building codes with just a single pane of glass, and no thermal barrier. Today, the aluminum industry is challenge to provide high performance storefronts, curtain walls, and window enclosures that maintain their structural integrity, provide good thermal performance and exceed the current codes in order to meet current and future challenges for energy savings."

One of the main challenges facing professionals is how to achieve carbon neutrality, or the design of a zero net energy building. The U.S. Department of Energy is encouraging research by providing funding for their goal to create marketable net zero initiatives by 2025.⁴ Net zero design initiatives mean that the project produces at least as much energy as it uses in a year. Near zero energy is a building that use some nonrenewable energy generation as a backup.

Structure, air, water, energy − these are the performance areas that are critical for frame manufacturers. Frames have to have structural integrity and meet new building codes that provide protection from hurricanes. They may also provide blast mitigation as well as meet high standards for energy performance. Sometimes the codes conflict − for example, the heavier material required for security may not be optimal for good thermal performance unless a thermal barrier is incorporated. Heavier glass required for security installations may also mean thicker, heavier frames to support the heavy dead loads, increasing the cost of the product. Different climates can also create different challenges for insulation, thermal performance and finishes.

A comprehensive evaluation of the requirements must be made to ensure the systems meet all of the requirements of the building structure. The American Architectural Manufacturers Association (AAMA) provides guidance on window performance in the AAMA 101/A440 standard. Window products classified with an AW Class designation are required to pass performance tests for air infiltration, water infiltration and structural performance as well as life cycle tests to ensure the products will stand up to the needs of the commercial market.

Aluminum is now one of the most recycled products used in manufacturing. Aluminum has a long life cycle Sunshade with thermal anchor as part of a façade system and can be recycled over and over again and still maintain structural stability. Using recycled aluminum means that the manufacturer uses only 5 percent of the energy that would have been used in raw Aluminum products. Architects are now specifying recycled content from manufacturers with very little additional costs for the system in order to meet LEED® requirements and to reduce the use of raw materials.

The new aluminum sunshade with a thermal break is one of the first aluminum products to have cradle to cradle (C2C) certification. C2C certification is defined as the evaluation of the eco-effectiveness of a product by assessing the materials used in its production as well as the production process itself, including the use of renewable energy, water conservation and stewardship, and the manufacturers' social responsibility.⁵ Manufacturers are well on their way to solving the issues of structural and energy efficiency to meet future codes.

The Tin Fish restaurant in Clinton Township, Michigan designed by Ron and Roman LLC uses a cementitious thinset exterior surface system on the exterior walls. Photo courtesy of Formulated Solutions LLC

Exterior surfaces −a new material that can reduce the use of fossil fuels

Thermal comfort is one of the main reasons humans build shelters. The exterior façade needs to manage moisture, insulate and temper the climate from the outdoors to the inside. Within this framework there are many building systems that contribute to successful thermal cladding. Cement-based, thin exterior surfacing systems provide a material alternative that reduces the product-cycle environmental impact while improving performance and increasing thermal comfort.

Typical of all exterior insulating finishing systems (EIFS), this system is comprised of a base coat, primer, and a 1/8-inch finish coat. In a one-coat stucco wall system, the finish and primer are applied over the stucco base. Unlike acrylic finishes, cementitious products are not petroleum-based. According to a compilation of three University studies,⁶ the initial embodied energy of this cementitious product is an order of magnitude (10 times) less than that of acrylic surfacing. Cementitious thinset exterior surfacing systems are a new class of building material providing:

• Long-term microbial resistance
• corrosion resistance
• chalk resistance
• increased color retention as a result of its resistance to UV degradation
• fire retardation

For all exterior claddings, professionals need to be knowledgeable about wall construction details, including vapor and weather barriers, flashing and drainage channels. Both acrylic EIFS and thin cementitious exterior surfacing systems provide good thermal barriers but the difference between the two is in the properties of cement that have environmental advantages over the petroleum based, acrylic, EIFS finishes. Cement provides both permeability and hydrophobicity.

As measured by a third party testing agency,⁷ the permeability of concrete thin set exterior wall surface has 3.3 to 4.2 times more water vapor transmission than the acrylic based EIFS products sampled.

Permeability is expressed in grains of water vapor/hour/ square foot at a known differential vapor pressure. Materials are classified by both the commercial and residential codes in several classifications and a class 3 vapor permeable material has a perm rate greater than 10 perms recommended for use in all climates.⁸ The higher the perms the faster water vapor will pass through or allow the wall to breathe, which eliminates mold in the building wall system. Vapor membranes used as part of a well constructed wall system have perm rates above 58. Combined with a cement thin set exterior surface, also with a high perm rate, this integrated wall system can provide a healthy solution for the prevention of mold or bacterial growth in hot humid climates without adding harmful biocides. Cement thin set finishes have also been tested for hydrophobicity and demonstrate a documented ability to shed water while allowing water vapor to escape from the wall system.

Other sustainable aspects of this new product are that it has zero volatile organic compounds (VOCs) that can be harmful to human health. This product is cement based and can be finished in numerous colors. Surfaces can be applied that are either uniform in appearance or mottled for a more natural, old-world appearance. The product is part of a sustainable construction process. It is delivered in bags and ordered by weight. When mixed with water, this stucco − like wet application is applied to the surface by trowel and will not leach harmful waste products into the soil. The weight for shipping is less than the acrylic EIFS system and may be eligible for regional credits in LEED® V3 depending on site location. Unlike acrylics, this product is supplied in easily disposable paper bags, there is limited waste on site, and the powdered product can be stored in unheated enclosures, without damaging its effectiveness.

This surface cladding has also been tested for durability and is formulated with a polymer modification to give greater elasticity and flexibility. This modification allows the cement to resist cracking from thermal changes and building vibrations in accordance with ICC specifications for use in both EIFS and one coat stucco applications.

Cementitious thinset exterior surfacing systems are extremely flexible. The illustration as shown was prepared as it would be on a job site. The base coat was applied to a flat sheet of foam; mesh was added and covered by more base coat and allowed to dry overnight. Then the finish coat was applied. The whole assembly was then bent into an inverted "U" without any sign of cracking. Flexible, permeable and durable, this exterior product allows the professional to select a wall system based on both its performance as well as its sustainable properties.

STRATEGY #5: Structural glass flooring
Optimizing safety, performance and daylight harnessing

When it comes to dramatic design elements, it is difficult to imagine anything more dramatic in appearance than the selection of glass flooring. Glass flooring can be used to bring daylight as well as drama to any interior, serving as a beautiful and inspiring focal point. Manufacturers now have the ability to produce and utilize glass flooring panels for exterior installation that is interior on one side and exterior on the other. They are able to add a separate layer of laminated glass to the bottom of the glass flooring panel via insulated glass technologies. This allows one to take advantage of the energy efficiencies of insulated glass with glass flooring panels.

Consider safety as the most important criteria when specifying glass-flooring. The glass flooring product should be durable and easy to maintain. To optimize occupant health and comfort, professionals should consider these main points:

ADA compliant anti-slip walking surface

An anti-slip walking surface needs to exceed the ADA (Americans with Disabilities Act) requirements of a static coefficient of friction of 0.5. Various anti-slip surfaces are available and it is important to verify that the selected surface meets the ADA requirements. One of these options is a glass aggregate that is melted into the top walking surface of the glass. This product, being a clear glass, allows for a clean line of site due to the lack of visual recognition of the anti-slip surface. Ceramic frit is another product that can be specified as a glass floor finish. This product is silk screened onto the top of the glass, much like a t-shirt is printed. The product is then baked onto the top walking surface during the tempering process. Some manufacturers have also produced sandblasted finishes, however, these are difficult to clean and become dirty quickly.

Glass make-up and structural integrity

To assure structural integrity, professionals should work only with an experienced manufacturer/supplier. A structural glass engineer should be used to determine the make up of the glass panels. Many manufacturers offer their own engineering for a small fee. The glass should be engineered to adhere to the new American Society of Testing and Materials (ASTM) standard which will be made published in the near future. It will state that the glass flooring panel should include 3 layers of glass and 2 layers of lamination. The panels should properly handle spans associated with deflection rates from standard applied weight.

Modesty/ Privacy

When specifying a glass flooring product, architects should review the privacy aspects of the installation. In public applications an "obscure" product should be used so that improprieties do not occur. This obscure or translucent product should still allow for light to pass through the glass.

Daylight harvesting

Daylight harvesting is the practice of capturing light from an exterior wall, by making adjacent walls and floors transparent so that light can travel freely across room interiors. The glass flooring product should allow for the maximum amount of daylight to pass. Therefore, the use of opaque anti-slip material should be avoided. Daylight harvesting reduces electrical consumption and provides access to nature by the occupants of a building. Numerous studies have proven that human performance is increased when exposed to daylight.

The intent of the Indoor Environmental Quality Credit 8.1: in the USGBC LEED® V3 reference guide is to provide occupants with a connection between the indoors and the outdoors. Using glass flooring panels for daylight harvesting is a means to create transparency or translucency for this important environmental strategy.

Exterior glass flooring installed over a water feature in a private residence in Hawaii. Photo courtesy of Jockimo Inc.

 

Exterior installations

Laminated glass products historically have not worked well in exterior applications when the edges of glass are exposed to the elements. The development of new and improved lamination products has eliminated this concern allowing glass-flooring products to be used outdoors in exterior applications.

STRATEGY #6: MEASURE 7: Energy Flows & Energy Future
Sustainable design conserves energy and resources and reduces the carbon footprint while improving building performance and comfort. Sustainable design anticipates future energy sources and needs.

LED Lighting − dark sky fixtures that save energy

In a recent Ken Burns documentary on the National Parks, a vivid image of the sky above Dinosaur National Park, located in Dinosaur, CO, revealed the majesty of the stars in the night sky. Most Americans now have to travel to see some of the major constellations because of light pollution. Manufacturers of light emitting diodes or LEDs believe that they have the optimal solution to meeting "sustainable sky" ordinances⁹ of many communities. LEDs are energy efficient and do not use any gas in their manufacturing process. The drivers used for operation contain no lead or mercury. Long life comparisons between LEDs and other types of lighting systems show that LEDs when properly installed can last up to 80,000 hours, many more than High Intensity Discharge (HID), fluorescent or incandescent light sources. Historically, LEDs have not been used for community street or site lighting; with recent advancements of LEDs, however, communities have a new option for saving money and reducing light pollution. And LEDs can now be used in street and site lighting to direct light where it is needed to avoid spilling onto adjacent properties, also known as light trespass.

New LED lights save money and energy. Chart courtesy of Kim Lighting

 

In street and site lighting, there are two areas of light safety design to consider. Designers light the ground plane using low level luminaires such as bollards and pathway lights, or an entire area by properly placing controlled, low glare illumination that can be mounted as high as thirty-five feet from the ground plane.

Sustainable lighting requires that the luminaire, regardless of the light source, is controlled to light the area required for safety without sacrificing the view of the night sky above. New LED lights with modular components or linear strips are designed to harness and direct LED light output.

LEDs continue to improve and have not reached their full potential, but it is already evident that they will save energy on many levels. The potential uniformity with LED allows the customer to use lower wattage to create safer environments with less money. As an example: A 150-Watt LED fixture could replace a 250-Watt Metal Halide product that uses 291-Watts of energy and save $56.00 per year on energy alone ($0.10/Kwh @ 11-hr per night). The additional savings are for not having to replace lamps every three years. Earlier LED light output performance was suitable for low level and landscape lighting, but with proprietary, micro-emitter technology and advances in LED technology, the diodes can be placed in individual modules and angled into any position, focused to provide the required lighting on the surface area. The DOE and ENERGY STAR are currently reviewing new criteria for lighting interior and exterior surfaces, to provide guidance for architects seeking to choose the most energy efficient strategy for their purposes.

"By 2011, the ENERGY STAR program will expand to include a wide variety of LED applications for general lighting. Until then, the ENERGY STAR program will identify specific types of lighting applications where LED performance is suitable for inclusion in the program prior to 2011. Some of these near-term applications will include street and area lighting, parking garage lighting, cove lighting, ceiling fan light kits, replacement bulbs, and display, accent and wallwash lighting."¹⁰ ENERGY STAR provides guidance as to specifying color temperature, spatial uniformity, color maintenance, rendering and off-state power (which means that the light should not draw power when turned off).

Chart showing options for color selections for LED lighting, including those for wildlife zones. Chart courtesy of Kim Lighting

 

Arizona State University Study

As part of a mechanical system, planted screens can shade a surface of a building providing as much as a forty percent swing in temperature, providing cooling relief in a tempered zone between the building and the exterior. In a study at Arizona State University's School of Architecture, planted green walls were designed to affect temperature along the light rail waiting platforms independent of a building structure. This study demonstrated that the ambient temperature was 8 to 10 degrees lower near the screens and also reduced radiant temperatures. Researchers used the standard effective temperature (SETA) index,11 to determine that the use of the green screen would support an ambient temperature that was acceptable for thermal comfort. The study measured high temperatures on the side of the screen with heat radiating sources and established lower values on the other, as well as a change in the humidity ratio. The cooling effect was a result of the evapotranspiration of leafy vines on the planted screen that provided both visual screening as well as temperature and humidity changes. In addition, studies from Germany show that biofilters remove particulates from the urban environment. Using plant materials in wall systems reduces noise as well as removes dust from the environment.

Planted screens cool passengers waiting for their trains in Phoenix, Arizona. Photo Courtesy of: greenscreen®

Designers who are concerned that color is limited by choosing the formerly "blue" LED will now be able to choose from a range of color temperatures. According to April Ruedaflores, Marketing Manager at Kim Lighting, "the first LEDs used in site and area lighting were limited in color temperature ranges." Today's LEDs can be offered throughout the spectrum, ranging from 5100 Kelvin (bright white) to the very yellow/orange light similar to High Pressure Sodium color range of 1700 Kelvin (amber). In fact, wildlife organizations lobbied for these amber colored lights for wildlife protection in coastal areas. The brighter lights, although more attractive to humans, disrupted nesting patterns of many species.

LEDs produce a lot of heat as well as light and as a single source, they can fail before their projected lifetime if not well ventilated. Manufacturers are designing internal thermal management systems to control the heat by creating housings that have aluminum conduits that provide a channel for the heat to be exhausted by cooling ventilators on top of light fixtures. LEDs also have drivers, similar to the ballast requirement of fluorescent and HID light sources. Good driver design is important as the driver also impacts the heat accumulation in the housing. Drivers also control the voltage output. All drivers are UL tested and drivers are rated for efficiency. Thermal management by design increases the LEDs output and longevity as well as the energy efficiency of LED lighting systems.

LEDs maximize their efficiency in cold climates but the expected output will depreciate in hot and humid climates. Although still providing an output greater than the alternatives, LED manufacturers provide charts indicating performance based on average outdoor ambient temperatures.

CONCLUSION

According to the AIA Committee on the Environment, "Sustainability envisions the enduring prosperity of all living things. Sustainable design seeks to create communities, buildings, and products that contribute to this vision."¹² Professionals are able to take advantage of new materials, new systems and new methods to assist them in achieving their vision of environmental sustainable design.

Celeste Allen Novak, AIA, LEED AP principal at rizzolobrown + novak architects specializes in sustainable design materials and methods and teaches as an adjunct professor at Lawrence Technological University.