Nine Ways Chemistry Contributes to High Performing Buildings
The choice of building materials is a key component in the construction of high-performing, or any, buildings. While designers are sometimes limited by the building type and size, they still must weigh a number of factors to pick which of potentially several options to use. Once the choice of building materials is made and construction has begun, it is harder to go back and change than it would be for, say, systems specified for the building.
Building materials have innate qualities that set them apart from each other. These intrinsic strengths and weaknesses, for the most part, cannot be altered by designers or engineers. More malleable brick or transparent concrete cannot be specified. Building materials are what they are.
What makes materials what they are is their chemistry—the composition, structure, and properties. Chemistry-related traits such as density, reflectiveness, adhesiveness, viscosity, and thermal properties not only define what materials are, but also what role they can play in the construction of a building. Indeed, the materials must ultimately have "chemistry" with each other, to act as the elemental "molecules" that make up a building and determine to a significant degree how it can perform.
Here are nine examples of how building materials' chemistry plays a role in the building process.
1. Energy-efficient, highly reflective roof coatings made from acrylics, urethanes, silicones, and styrene block copolymers (such as SBS and SEBS) can lengthen the life of a roof, help lessen air leaks, reduce heat transfer and decrease thermal shock that occurs when different layers of the roof expand and contract.
Case Study: A government center building in Doral, Florida, features highly reflective roof coatings that help lower energy use. A reflective cap sheet on the roof reflects the sun’s heat off of the building, keeping the building’s interior cooler and reducing air-conditioning costs.
The chemistry connection: Scientists fine-tune the chemical materials used to create roof coatings by controlling film thickness and layering UV resistance, enabling more options for builders and architects.
2. Lightweight yet durable materials like polyurethane help builders do more with less.
Case Study: The city of Edmonton, AB, Canada, recently refurbished its historic Dawson Bridge, lightening the load of the bridge deck by adding a polyurethane core between the bridge’s two steel plates while adding high rigidity and strength.
The chemistry connection: The discovery of polyurethane dates back to the beginning of World War II, when chemist Otto Bayer developed it as a replacement for rubber. It wasn’t long before the material was used in building and construction applications, thanks to its strength-to-weight ratio, insulation properties, durability and versatility.
3. Continuous insulation is an innovative building science design that creates an uninterrupted blanket of insulation, which improves the energy efficiency of a home or building by minimizing air infiltration, which can amount to as much as 40% of the heating and cooling loss in a typical home. The added insulation also helps meet current building energy code requirements for wall and roof R-values, contributing to a higher R-value for the building envelope.
The chemistry connection: Continuous insulation is an assembly approach to designing a building envelope that often involves the use of thermosets (polyurethane foams—spray and polyiso rigid board) or thermoplastic foams (polystyrene, extruded polystyrene or extended polystyrene) as the primary insulator. These foam insulation products can be spray-allied, in the case of spray polyurethane foam, to form a continuous layer of insulation or installed as insulation board. Any “seams” between insulation boards are tapped or sealed together to wrap the building in a “cocoon” of insulation.
4. Cross-linked polyethylene (XLPE or PEX) is used to make flexible hot and cold water piping that can be threaded and curved into a variety of configurations, reducing installation time and cost and revolutionizing indoor plumbing options.
Case Study: The Minnesota Vikings will debut its new home field, U.S. Bank Stadium, this summer. It uses XLPE piping on its pitched roof to keep snow from sliding off and onto the playing field below. Also, hot water running through the XLPE tubes raises the surface temperature of the roof to melt snow before it accumulates.
The chemistry connection: Polyethylene is a flexible, lightweight synthetic resin used in consumer products such as packaging and water bottles. In building applications, the cross-linking process can change the temperature and impact resistance of materials.
Vinyl is composed of two simple building block chemicals: chlorine, produced using common salt, and ethylene, derived from natural gas. This chemistry helps create luxury vinyl tile (LVT), used to create resilient flooring surfaces in many modern building.
5. Vinyl, often referred to as the “infrastructure plastic,” has been used in building and construction for decades, and innovations in material science offer new applications for this stalwart material. For example, luxury vinyl tile (LVT) offers high-end aesthetic designs and patterns for flooring surfaces that can be both warmer and more comfortable underfoot than ceramic tile. LVT can be installed with or without grout. And outdoor vinyl trim looks and acts like wood trim while resisting moisture, rot and decay.
The chemistry connection: Vinyl is composed of two simple building-block chemicals: chlorine, an element that can be derived from common salt, and ethylene, derived from natural gas. Because vinyl’s chemistry enables the material to be formulated to be either flexible or rigid, architects and builders have more freedom in designs and can also reduce the amount of cutting and cutoff wastes that occur with intricate shapes when installing vinyl trim, for example.
6. Chemistry helps make concrete that is 100 times lighter than concrete made with traditional fills like soil. Polystyrene beads added to dry cement powder makes concrete that is lighter weight and easier to transport without sacrificing durability and strength.
Case Study: This science-powered concrete blend, used in both of the new World Trade Center Buildings in New York City, and the Burj Khalifa hotel in Dubai, United Arab Emirates, the tallest building in the world, provides structural strength and also is a good insulator.
The chemistry connection: Adding polystyrene beads to dry cement lowers the viscosity of the mix so it can be pumped more easily up to floors higher than 100 stories.
7. Nanotechnology is used in a variety of applications: to create corrosion-resistant pigments and coatings, heat management coatings and antimicrobial coatings, as well as lightweight composites. Glass buildings with “smart” windows featuring nanotech electrochromic glass can change from clear to opaque and back at the touch of a buttonto shade the building from direct sunlight and promote energy savings while maintaining the window’s aesthetic appeal and transparency.
The chemistry connection: Nanotechnology is the engineering of very small materials on a molecular scale. As a result, materials can be designed and specified at levels even smaller than a strand of DNA, which measures 2.5 nanometers in diameter. For example, nanotechnology enables extremely small structures called carbon nanotubes, measuring only one nanometer. This microscopic science helps researchers work at remarkably small scales and is already bringing benefits in areas such as health care, the environment and energy—including new technologies that can target cancer cells deep within the body, remove pollutants from groundwater and soil, and enhance the performance of solar panels.
Case Study: One New York-based architectural firm is already researching how carbon nanotubes might create buildings with features such as windows and doors that can move on their own.
8. Engineered wood products, including plywood, veneers, particleboard, fiberboard, engineered beams, and trusses, are made by using adhesives to bind or fix wood particles or fibers to form composite materials that are often harder, denser and stronger than solid wood. Engineered wood products are used in a variety of construction applications, from simple beams and headers in a house to soaring arches for a stadium’s domed roof. For building lobbies and atria that require tall walls and large open spaces with minimal intermediate supports, engineered wood products can enable builders to construct spans as long as 100 ft (30 m) and walls up to 20 ft (6 m) tall.
The chemistry connection: The chemical compound formaldehyde contributes to the sustainability of engineered wood products. Formaldehyde-based resins and glues are added to wood chips, wood waste or sawdust that might otherwise be disposed of to create particleboard and fiberboard used in making cabinets and laminated countertops.
9. In many modern buildings, glass is the primary exterior building material. Structural silicone glazing (SSG) helps glass achieve larger spans and dimensions. This happens when specific silicones are used to bond glass and metal panels to a structurewithout the use of mechanical fixation. As a result, SSG allows for aethestic facades, impressive curtain walls and large, unique windows in modern buildings.
The chemistry connection: Silicones can bond materials together with staying power and lightness, as well as be designed and specified for permanent or temporary adhesion. The benefits of silicones as a material rely on its chemical structure. Silicone’s chemistry binds together materials that traditionally can be difficult to bond, such as glass, metal and stone. With silicone technology, formulators are able to define the exact characteristics of the bond needed. A silicone-bonded system provides weather-ability and UV resistance to a structure. It also allows glass glaze to resist wind load, dead load and thermal dilation.
These nine innovations are just a few of the materials that transform buildings. Visit http://www.buildingwithchemistry.org to learn more.