Blending Aesthetics and Sustainable Design Through Facades  

The building’s facade is the first thing people see when they gaze upon a skyline or down the street. The facade is not only there to evoke a feeling upon first impression, but it also serves as a vital part of the building envelope. In short, the building envelope is meant to keep the outside out and the inside in while providing occupants with a safe and comfortable environment that will promote their physical and mental health and welfare. The challenges presented by the environment and exacerbated by climate change put added pressure on the building envelope, which can lead to unwanted air and moisture intrusion and all the costly hazards and repairs that follow. Thanks to technological advancements, modern architectural features not only help protect the building envelope against wind, rain, water, and snow, occupants do not have to sacrifice comfort, energy efficiency, or sustainability to enjoy aesthetically pleasing facades. Striking the balance between beauty and function, a well-designed facade can provide the means to ensure that a building is both easy on the eye and easy on the environment, as high quality, long-lasting sustainable materials also require less maintenance and fewer updates or replacements.

MATERIAL SOLUTIONS FOR HIGH QUALITY FACADE

With many different materials available on the market, building designers and architects have a myriad of options to choose from. High quality, sustainable materials are often a blend of naturally occurring and manufactured materials, thus combining the natural weatherproofing qualities provided by Mother Nature with man-made technology solutions.

A key attribute of sustainability is to ensure the balance of natural materials left in nature when extracting them or making a concerted effort to replenish them. Combining natural materials with man-made materials can help make them more durable and increase their life span, preventing an early trip to the landfill. Specifying products that can be recycled or repurposed at the end of their life span is another way to further decrease material impact on the environment.

After a material is selected, it can be treated with coatings or glazes not only to ensure an aesthetically pleasing facade, but also to provide additional protection against the elements, improving the health, safety, and well-being of occupants. Materials can be cut into various shapes and sizes. Coatings and treatments can be applied to update textures, colors, and even designs.

Sintered Stone

Sintered stone is a fairly new material that combines a perfect blend of man-made processes with natural materials to create surfaces that can withstand both natural elements (hurricanes, blizzards, driving wind and rain) and man-made elements (industrial smog, graffiti). This durable surface is resistant to water, chemicals, scratches, abrasions, and thermal shock, making it a facade material of choice for architects and specifiers worldwide.

Sintered stone can be used for exterior building projects, whether commercial or residential, especially in areas where added thermal and weather protection is needed to protect against extreme temperatures and driving rain or snow. While it is 100% natural in composition, sintered stone can be treated with another material agent to transform the slab into a self-cleaning, anti-pollution, air purifying surface perfect for use in busy, high-emission urban environments.

This natural premium surface is produced in a carbon neutral environment and is one of the most sustainable facade materials on the market. Using 100% natural raw materials, a variety of surface designs can be manufactured including wood, marble, and metal. High performing, ultra-resistant, and low maintenance, sintered stone is available in over fifty colors, patterns, and finishes, providing a striking appearance by combining aesthetic appeal with longevity and resilience.

Natural Stone

Natural stone works well in exterior facades. It has the lowest embodied carbon of any fascia/cladding material – four times lower than timber, 3.3 times lower than brick, and 10 times lower than terracotta, ceramic, or architectural precast with high cement or steel content. Natural stones such as sandstone, limestone, and granite can be combined with ultra-high performance concrete (UHPC) into a thin, lightweight, high performance cladding system. This innovative low-weight facade system does not require the use of aluminum, steel, or precast concrete, leaving a much lower carbon footprint. Brick, terracotta, and wood also can be unitized on thin, lightweight cladding panels made of UHPC.

Natural stone can emulate and achieve the look of other less sustainable materials. Faux joints in large natural stone panels can mimic the look of brick or terracotta, as well as yellow or red sandstone.

Performing as a decorative rainscreen, or even a load-bearing outer wall, natural stone has a high thermal mass and a low U-value which reduces the amount of heat loss in the winter and heat gain in the summer.

Natural stone is also highly durable. A well-maintained natural stone facade can easily last 150 to 200 years as it does not use or require structural silicone like glass curtain wall.

Ultracompact Surface Material

The ventilated facade is a high performance solution for building enclosures, which takes advantage of mechanical anchoring elements. Through connections between the siding material and the mechanical assembly, design loads are effectively transferred back to the structural wall, providing a safe and secure facade.

For facades fixed with glue, it is very important to select the appropriate adhesives. Mechanical tiebacks or safety brackets can also be incorporated as needed.

Spandrel panels are used in place of glazing units in curtain wall systems when hiding the edges of floor slabs, celling details, insulation, or other building elements.

Ultracompact surface material is available in large format panels (126-by-56-inch) and varying thickness (8 mm, 12 mm, and 20 mm). This material has excellent dimensional stability with a reduced number of joints needed, thus limiting the number of openings in the building envelope.

These panels come in many colors and styles leading to endless design possibilities. Reduced porosity means this material is easy to clean, and resistant to water absorption, thermal shock, extreme heat, graffiti, and freezing.

Thin Brick

Thin brick is a thinner version of a full-face brick that can both functionally and aesthetically work with traditional face brick. Thin brick uses less material and so proves more cost-effective, creates a smaller carbon footprint, and is less expensive to ship. Thin brick is also easy to install. This product can be used in places that were once thought to be physically impractical or too costly for application, such as large stadiums and massive sports arenas.

Thin brick is available in many colors and textures to match the aesthetics of face brick counterparts. Some thin brick comes with a “keyback” design that protects the wall system from having the brick pull out when used in precast or tilt-up applications, allowing the thin brick to be better used in a panel system when applied. The keyback design also offers a seamless look and feel when transitioning from thin to face brick on a single facade.

Glass Expanses with Low-e Coatings

To achieve bright beautiful buildings with plenty of daylighting for occupants, architects can specify low e-coated glass in larger expanses without sacrificing energy efficiency and sustainability. Low-emissivity (low-e), low-iron glass can be used to create views so clear and crisp that it’s hard to believe the glass is even there. Low-e coatings are engineered to minimize the amount of harmful ultraviolet (UV) and infrared light that can pass through the glass without compromising the amount of visible light that is transmitted. A microscopically thin transparent coating allows low-e glass to reflect exterior heat in warm temperatures and hold in heat during cold temperatures. This helps prevent unwanted heat exchange, reducing the need for HVAC to maintain occupant safety and comfort.

Building-Integrated Photovoltaics (BIPV) options are also available, allowing the integration of solar cells into the building envelope. BIPV materials simultaneously serve as the facade, the building envelope barrier, and as a source of power generation. The systems can help increase the value of the building by enabling it to produce energy while also reducing electricity costs, use of fossil fuels, and emissions.

Expansion Joint Systems

To ensure that the building envelope is designed, specified, and installed to protect the interior and its occupants against the elements, facades must ensure that all seams and joints are adequately sealed. These systems are an integral part of many buildings due to expected movement that naturally occurs over time. Expansion joint systems not only allow for movement but are also designed to provide additional moisture and fire protection and to handle unique conditions within a building.

Closed-cell foams are absolutely watertight and do not allow moisture to enter the body of the foam. This is the best application for horizontal runs where water could pool. The other key advantage of closed-cell foams is that they take well to heat welding of seams. This renders a monolithic installation that reduces risk of water infiltration.

Compression seal joint systems are installed into a joint block out and absorb movement and flexing through compression of the seal. The product is also an excellent option for exterior applications where waterproofing is required.

The hybrid design of a compression seal system is designed to deliver a greater level of waterproofing in split slab construction. A key benefit of this system is its integrated counterflashing, which is engineered to channel water away from the joint opening.

A roof bellows system uses either an ethylene propylene diene terpolymer (EPDM) or a neoprene seal that flexes to accommodate seismic movement. As with counterflashing, the seal must run under the metal flanges to allow water to be shed away from the joint opening. In addition, a compatible non-reacting mastic should be used to ensure watertight adhesion of the seal.

A reinforced vapor barrier (RVB) is another option that can be specified to prevent water infiltration or channel water via an integrated drain tube to drain locations.

A SYSTEMS APPROACH

In the design and planning stages, architects and specifiers must consider how all aspects of the building will work together to ensure that the end result is a high performance building that provides occupant health, safety, and comfort.

The building envelope is the first line of defense when it comes to keeping outside air out and inside air in. Whether designing and constructing a new building or renovating/retrofitting an old building, it’s important to understand the entire building envelope system as having a direct impact on energy use and indoor air quality (IAQ). According to a 2015 report from the U.S. Department of Energy, “about 50% of the heating load in residential buildings and 60% in commercial buildings results from flows through walls, foundations, and the roof.” Energy created within the home that flows to the exterior is just one of the problems caused by a poorly sealed building envelope. Unwanted intrusions from outside the building also can penetrate the envelope, flowing inside and harming the building’s structure and its occupants.

Over the past several decades, huge technological advancements have been made to materials, products, and construction best practices. The adoption of new technology and high quality products is becoming increasingly important as the effects of climate change are leading to increased instances of extreme weather that can directly impact the building envelope. Dramatic temperature swings as well as increased flooding in some areas – while others experience extreme drought – can leave an area susceptible to wildfires, and unprepared buildings are more vulnerable to costly damage. Areas that typically have precipitation are suffering from larger and more intense storms such as hurricanes that can produce dozens of inches of rain in a single storm, or blizzards that drop large amounts of snow.

All of these conditions strain buildings and threaten to damage the building envelope, allowing unwanted air and water to penetrate building materials. As flood waters recede or blizzard snows melt, the buildup of water can flow into spaces around exterior flashings or expansion joints. If not prevented or quickly remedied, unwanted moisture intrusion can cause catastrophic physical damage that is not only expensive to fix but also can be harmful to building occupants. Mold and mildew can easily grow in water-damaged spaces, leading to poor air quality and causing physical harm to occupants.

By keeping outside air and moisture outside, the building envelope assists other systems. For example, the HVAC system works more efficiently to keep occupants comfortable with consistent temperatures and safe with improved air quality.

Many natural and man-made materials can help seal the exterior facade by providing natural water and moisture resistance.

Sintered stone has a porosity of less than 0.09 percent, so it doesn’t easily absorb water. By keeping water out of the surface material, the building is less likely to be affected by water penetrations and subsequent staining, mold, or mildew on the exterior facade. Sintered stone is also resistant to thermal shock, making it suitable for any climate.

Ultracompact surface materials are shown to be impervious with an average water absorption rate of 0.03 percent. They also have an average moisture expansion of 0.02 percent and an average abrasive wear index of 182.2.

Natural stone can be manufactured in large panels that contain faux joints to achieve the look of brick or terrracotta; a single panel may appear to have more than a dozen bricks. Fewer seams and fewer spaces between panels leaves fewer ways for water to penetrate the building envelope.

Thin brick fastened using the “keyback” method is less likely to separate or pull out from the main structure, reducing the risk of wall damage that can lead to air and/or moisture intrusion. Thin brick also is lighter and creates fewer seismic concerns as it requires less structural support while providing a genuine brick appearance. Thin brick is significantly less expensive than classic full brick because it is much thinner and therefore uses less material.

Low-e glass coatings help prevent the amount of heat transfer on either side of the glass. They help keep hot air outdoors in summer but warm air from the HVAC system indoors in winter. With low-e coatings preventing heat transfer, an HVAC system doesn’t have to work as hard to maintain temperatures for occupants, and energy costs are reduced. Occupants also experience the added benefit of comfortable temperatures without needing to use curtains, blinds, or other means to block light from the outside to keep unwanted heat or glare from entering a space.

Expansion joint systems help seal gaps between panels and spaces in the building envelope. These joint systems are vital in preventing air and moisture intrusion from entering the building.

Allowing the building envelope and the HVAC system to work together rather than in opposition of one another not only saves the occupant energy costs, it also promotes the health, safety, and welfare of occupants by preventing them from exposure to toxic mold, mildew, or other harmful materials in the wall structure.

DESIGN AND AESTHETICS

When specifying materials and products for facades, it is also important to consider how the material will be manufactured, shipped, and installed. For large scale commercial projects, large panels can provide options for unique, visually stunning facades. Panels can be cut into custom shapes and offer infinite options as to how they are displayed. Large panels can even include designs that give the illusion that the panel is made up of many smaller pieces of different shapes and sizes. However, the major benefit to having large sheets and panels is that there are fewer seams or areas where water and moisture can seep into the building.

Sintered stone is a lightweight product that can be cut to almost any requirement, making it cost-effective to ship and easy to fabricate and install. The material can be affixed to a building’s structure by using one of the following systems:

Hidden Fixing with Longitudinal Adhesion (HC): Comprised of a hidden support system that uses a longitudinal elastic chemical adhesive with a vertical support featuring T- or L-profiles.

Visible Mechanical Fastening Fixation (VM): Comprised of a self-supporting metal structure for ventilated facades designed to support ceramic tiling in different formats and thicknesses.

Strongfix: A longitudinal mixed (chemical and mechanical) hidden profile system.

Natural stone can be shipped as large-scale, thin, lightweight prefab panels on UHPC. Natural stone not only creates a unique facade, but it also reduces the carbon footprint in manufacturing processes, transportable weight on the roads, and the structure.

Ultracompact surface materials can be specified, manufactured, and cut into large panels for a visually appealing facade that has fewer seams that need to be sealed in the building envelope.

Glass panels can be manufactured, cut into various large panel shapes and sizes, and installed on the exterior facade. Tempering processes during manufacturing as well as glass coatings help reinforce the glass, making it more durable and aesthetically pleasing both for occupants indoors and for those viewing the structure from the outside. Coatings also can be used to reduce heat transfer and glare.

SUSTAINABILITY

In addition to creating aesthetically pleasing and unique facades, natural and durable materials promote sustainability in a few different ways. The first is by reducing the carbon footprint through a reduction in energy usage during manufacturing as well as for the life of the material.

Manufacturing of thin brick uses significantly less energy when compared to manufacturing full-width brick. A larger number of thin bricks can be transported in a single shipment, thus reducing carbon emissions used in transit. Thin brick also can help increase efficiency by absorbing and then storing heat, slowing its movement through the wall. The thin brick veneer can hold the heat on the exterior rather than releasing it to the inside of the building, in this way helping to reduce strain on the HVAC system and lowering energy costs.

Natural materials such as natural stone do not require additional firing or processes compared to man-made materials such as glass, concrete, steel, brick, or terracotta. This ensures additional heat and carbon are not released into the atmosphere by a kilning/sintering or firing that can be 2000°F or more.

Waste created in the quarry and during fabrication, can be reused and recycled to make aggregate, calcium carbonate, and substitute recycled content. Stone sludge from sawing blocks can also be used in green brick which contains up to 60% recycled content.

High performance materials can be thinner and therefore use less carbon, not only in the incorporation of materials but also during manufacturing and transportation to job sites. The weight reduction of the large-scale thin facade natural stone panels on UHPC is light enough to be floor-loaded, leading to a tremendous reduction in weight during transportation as well as on the superstructure and foundations, all of which allows an additional reduction in carbon emissions.

Durable materials are built to withstand the elements and therefore do not regularly require extensive repairs or early replacement. Long-lasting materials like natural stone can be employed for extended periods of time. While the initial cost of some materials may be higher when specified and installed, costs can be recuperated in energy savings over time and a longer lifespan. Additionally, materials that have a longer life do not need to be replaced, and so they do not end up in the landfill or need to be recycled as frequently.

In thin brick applications, the keyback design provides a mechanical lock into the concrete for maximum durability and permanence. This design brings added strength and performance with an increased sheer value and pull-out strength. Both of these attributes lead to a longer product life and fewer replacement costs along with less material waste. When brick does reach the end of its life, it can be recycled as it is made from abundant, natural materials.¹

Jessica Jarrard is an independent writer and editor focusing on health, science, and technology. She contributes to continuing education courses and publications through Confluence Communications. www.confluencec.com

End Note:

¹Quadrennial Technology Review. An Assessment of Energy Technologies and Research Opportunities. Chapter 5: Increasing Efficiency of Building Systems and Technology. Department of Energy. 2015