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Cover Story

November 17, 2008
Volume 86, Number 46
pp. 15-23

High–Performance Buildings

Green designs depend on materials that reduce the energy footprint

Melody Voith

EIGHT YEARS AGO, when Jean Merritt and her husband bought land in the Nob Hills of southern Indiana, they figured it would be a peaceful place to retire. The land didn’t include a house, so Merritt began planning to build one. “I wanted it to be as environmentally friendly as possible,” she says.

Gray, The New Green Neopor insulation is made from polyurethane beads that contain reflective flakes of graphite.

But building a green house was not a relaxing experience. Merritt spent years on research, collecting information and product recommendations from books, websites, and Internet discussion groups. “There was a lot of disagreement within the community about what is green,” she recalls. “You have to sift through people’s motivation. Are they just trying to sell you a product?”

To the consumer, the marketplace for green building materials can be a confusing jumble of eco-friendly lumber, recycled glass tiles, concrete blocks made with fly ash, and old-fashioned “natural” linoleum. But experts agree that a truly environmentally friendly building is one that is energy efficient and long lasting. And they say performance materials—often supplied by the chemical industry—are indispensable in crafting such a building.

Choosing among the various materials was not the only step that gave Merritt trouble. She also had difficulty finding a local builder and local sources of building materials. She was not able to get mineral wool insulation, certified wood, nontoxic glue, or special passive solar windows. Construction finally began in 2005.

Eric Smith, senior builder at the home construction firm David Weekley Homes, is not surprised by Merritt’s report. Most home builders are not in the market for green materials, he says, which means distributors don’t carry them. “We’ve always struggled,” he continues. “One of our company goals is to always be on the cutting edge. Any time we make a change like using a green material, our standard suppliers don’t have the product. When we built 1,500 homes per year in one market, we could pressure the supplier because we’re big enough.”

The roadblocks Merritt and Smith encountered highlight the problems that makers of green building materials face in getting their products adopted by a conservative industry. Manufacturers say that it can take 15 years for a green product to enter the mainstream and that communicating the value of innovative products to suppliers and builders is their biggest business hurdle.

The most common complaint of builders is that green materials add to the cost of construction. However, the average add-on of 3 to 5% is earned back in the early years of the building’s life due to less expensive operation, mainly lower energy bills, according to Jack Armstrong, director of building and construction for BASF. But he points out that builders usually aren’t responsible for the utilities and aren’t swayed much by promises of future payback for someone else.

Commercial builders who own and lease office space have more skin in the game, although they will want to see proof that a material performs well. Making the sale may require environmental analysis, energy modeling, and cost of ownership studies. The most important piece of evidence is how well the material works in a model building, Armstrong says. “We have to illustrate the benefits through practical examples in the field.”

AND THAT'S not all. Manufacturers say high-performance products only work as advertised when they are installed to precise specifications by skilled builders. Each new innovation requires training, but suppliers say few builders take advantage of their training guides. “We’ve lost that master-journeyman-apprentice structure. A lot of the work crews are not professionals,” says Joe King, global technology manager for DuPont Building Innovations.

“It’s one thing to spark innovation, but good ideas don’t sell themselves and certainly don’t install themselves,” agrees Scott Young, global director of energy efficiency at Dow Building Solutions. “We’ve used a lot of resources to ensure builders know how to use our products. Innovation from chemistry and science has to get outside the lab and on to the job site. It can’t exist just in beakers.”

SAGE Electrochromics
Light Dimmer The metal oxide coating on Sage window glass allows users to control the amount of daylight that enters a building.

One might wonder why manufacturers even bother. The reason is strong demand. Architect John A. Boecker of the green architecture firm 7group says his clients’ growing awareness of environmental issues and their concerns about energy prices “have converged in a magical way, truly transforming the marketplace.”

According to the U.S. Green Building Council, the market for green building products and services was $12 billion in 2007 and is projected to increase to $60 billion by 2010. USGBC says green is the new definition of class A office space, because it brings in 10% higher rents on average.

Yet definitions of green vary. Clients may focus on natural-looking finishes and recycled materials, but hard-nosed architects have recognized that energy efficiency trumps other environmental qualities.

“Most green buildings don’t actually work because they don’t save very much energy. Instead, people focus on making a statement,” asserts Joe Lstiburek, principal of Building Science Consulting, a firm that advises builders on design and materials. “But the focus is shifting, and has to shift, to high energy efficiency. That will be the most important metric. It’s inevitable.”

Lstiburek points out that the shift is meaningful for the chemical industry. “There is a huge opportunity for performance materials,” he says.

BASF’s Armstrong is pleased by the change in focus. “We talk a lot about high-performance products, rather than green. Performance is something you can measure. People say, ‘I need a building that uses less than X energy per square foot,’ or ‘I need a roof that meets specifications for a hurricane.’ ”

Different types of buildings and different geographies require different levels of performance, but the most important characteristics are usually energy efficiency, strength, durability, moisture resistance, and ease of installation, Armstrong says.

“Good ideas don’t sell themselves and certainly don’t install themselves.”

In the U.S., when commercial realtors advertise a “green building,” they usually mean it has received Leadership in Energy & Environmental Design certification. USGBC introduced the LEED certification for new commercial construction in 2000.

LEED certification depends on earning points in five key areas: sustainable site development, water savings, energy efficiency, materials selection, and indoor environmental quality. By accumulating points in these areas, buildings may earn certified, silver, gold, or platinum LEED status. The U.S. now has more than 35,000 LEED-certified buildings of all levels.

USGBC will release updated LEED certification standards in 2009 that require builders to earn more points for lowering energy use and impact on the atmosphere. According to the Department of Energy, buildings account for 74% of U.S. electricity consumption and 39% of CO2 emissions. That means commercial and residential buildings have a larger effect on climate change than transportation or industry.

Merritt did not have LEED guidance when she built her house; USGBC didn’t release the LEED for Homes program until late 2007. But she discovered in her research that she could get the most environmental benefit by selecting materials and designs that reduce the amount of energy needed for heating and cooling.

In the end, she chose a combination of natural and man-made materials. Wall interiors are made of insulating straw bales. The aluminum roof has a reflective coating to keep the house cool, and underneath, structural insulated panels filled with polyurethane foam add additional thermal protection. South-facing windows are equipped with deep overhangs so the sun keeps the house warm in winter but shaded and cool in the summer.

The focus on energy is giving Dow and other material makers a sense of déj?? vu. “Styrofoam insulation gained a foothold in the ’70s energy crisis,” Young says. “Now, again, rising costs and our dependence on fossil fuels have triggered a strong resurgence in looking at energy efficiency and energy conservation.”

But the thinking has evolved since then. Modern green-building techniques focus on multiplying the power of energy-efficient materials by understanding the interactions of a building’s many systems. According to Boecker, the architect, this approach is similar to the role of the master builder, common before the industrial revolution, who exerted top-down control over skilled tradesmen and laborers.

Easy Pieces Dow’s Thermax Total Wall System marries foam insulation to a water barrier for commercial construction.

“ALL THE ELEMENTS—structural, aesthetic, mechanical, lighting, landscape, civil engineering, utilities, and stormwater management—have direct and indirect impacts on every other,” Boecker argues. “The key to high performance is understanding those interactions. The team members must work as an integrated organism.”

Reducing the energy footprint of a structure requires control over the flow of energy between the interior and exterior of the building. Since about half of the energy a building uses is for heating, ventilation, and air-conditioning (HVAC), DOE suggests paying special attention to the building’s envelope—the foundation, walls, roof, windows, and doors.

A tight, well-insulated building envelope allows building designers to specify smaller, more energy-efficient HVAC systems. Smaller units cost less, take up less space, and bring lower energy bills.

The common metric for measuring the performance of a building’s envelope is as old as Styrofoam—the R value. R value is a measure of the ability of a material, such as insulation, to slow the transfer of heat or cold. It varies greatly depending on the material’s composition, thickness, and coating.

By that measure, most natural materials are poor insulators and take up too much space to get the job done. Polyurethane foams are used in many applications because they have R values typically around 7 or 8 per inch, according to DOE.

Energy efficiency requires polyurethane, Lstiburek says. “Wood-frame home construction will need high-performance insulated sheathing. Commercial construction will be driven to use new two-component spray polyurethane foams.” He adds that the spray foams also provide air tightness and vapor control.

Polyurethane insulation ingredients include isocyanates, polyols, fire retardants, coatings, and adhesives. Many chemical companies supply insulation ingredients to the construction industry, including Air Products & Chemicals, Albemarle, Ashland, Evonik Industries, Huntsman Corp., Lubrizol, and Bayer. Dow and BASF make insulation components and also manufacture finished products that builders can purchase.

Although most polyurethane products are based on chemistry that has been around for more than 50 years, the chemical industry is looking at ways to improve the products’ environmental profile. Dow has invested in research and manufacturing capacity to use soybean oil as a polyol raw material, reducing dependence on petroleum as a feedstock and lowering greenhouse gas emissions.

BASF’s Styrodur rigid polyurethane insulation is a green color to advertise that it is made without chlorinated or fluorinated blowing agents that deplete the ozone layer. Instead, its cells are filled with air. Another BASF product, Neopor, is also easy to spot. It is made with microscopic flakes of graphite and has a distinctive gray color. The graphite reflects heat so the insulation can be made thinner. Less material means less petroleum is used and less landfill waste at the end of its lifespan.

Merritt’s choice of structural insulated panels (SIPs) for her Indiana home provides a window into the future of new building practices. SIPs are gaining popularity as a modular, multifunctional outer material for walls and roofs. The panels are made from a layer of foam (polystyrene or polyurethane) sandwiched between two layers of fiber board, plywood, or fiber-cement blend.

Traditional modes of residential construction involve wooden framing and studs, wall bracing, rolled or blow-in insulation, and plywood sheathing topped off with a weatherproof layer and external siding material. The insulating layer is interrupted every 16 inches by the wood studs, allowing as much as 30% of the energy in a building to escape in the form of heat.

SOURCE: Energy Information Administration
CLIMATE IMPACT Buildings are responsible for 39% of CO2 emissions in the U.S.

ACCORDING TO manufacturers, the benefit of SIPs over traditional methods is that they provide a continuous layer of insulation around the building and add enough structural support to replace bracing between the studs. The website buildinggreen.com, an independent builders’ resource that evaluates green materials, lists 21 different SIP products.

Lstiburek points out that SIPs are considered a premium product and currently have a small market penetration. But that may change. Structural components account for nearly three-quarters of the U.S. market for green building materials, according to the market research firm BCC Research.

Dow is market testing its new Styrofoam Insulated Sheathing, which adds a water-resistant barrier and makes the SIP a three-in-one system of barrier, foam, and proprietary fiberboard. The new Dow panels are only 0.5 or 1 inch thick and have an R value of up to 5.5.

Young highlights the performance characteristics of Dow’s new panels as “ease of installation and reduced up-front costs. There are fewer materials to stock and ship and less need for labor.” The panels also reduce the need for separate insulation, are made with 80% postconsumer waste, and weigh less than half of traditional sheathing, he says.

Armstrong also uses practical measurements to convince builders to adopt BASF’s SIP product. “We hired third-party construction analysts to document the hours of labor required to build a wall. They did a time-and-motion study and found that using our product takes 50% less time compared to traditional walls and requires less labor to frame and sheath a 2,000-sq-ft house,” he reports.

It’s not just wood-frame houses that purveyors of new construction materials are targeting. They’re setting their sights also on buildings made with concrete, steel, and glass.

In the southeastern U.S., many houses and low-rise commercial buildings are made from concrete. Builders can now choose from different types of insulated concrete forms (ICFs), such as those made by Reward Wall Systems.

ICFs feature expanded polystyrene that provides structure for poured concrete walls. After the concrete is poured inside the forms, the polystyrene becomes part of the wall, providing a barrier against heat transfer. The concrete and foam together have an R value of 22, according to Reward, and are strong enough to withstand a class 5 hurricane.

Green Buildings Are...

Energy efficient—in operation and in construction

Resource efficient—in operation and in construction

Nonpolluting—in operation and in production

Durable—so they can be used for a long time

Adaptable for many uses—so they can be reused easily

Healthy—allowing fresh air with few chemical emissions and no mold

Beautiful and comfortable—so people will want to use and reuse them

SOURCE: Building Science, buildingscience.com

IN URBAN CENTERS, most high-rise apartment and commercial buildings are constructed from steel frames. Because metal is an especially poor insulator, exterior wall systems and cladding can make a big difference in energy efficiency, according to Young. Dow’s Thermax Total Wall System combines a polyisocyanurate foam core with an air barrier of spray polyurethane foam and adhesive flashing for windows and doors to keep out moisture. The system provides an R value of up to 14.

In addition, the architectural style of high-rise commercial and condo buildings is often the “glass box.” However, big windows are a major concern of green-building advocates, who point out that any hole in the envelope for windows, doors, sunroofs, or mechanical systems can be a breach of a building’s energy efficiency.

Architects and building occupants love the benefits of daylight and window views. But according to the consultants at Building Science, even the best windows have R values that only approach 3, and windows permit roughly one-third of the sun’s heat to enter the building. The heat buildup increases the burden on air-conditioning systems.

New dynamic glazing technologies may allow architects to keep the aesthetic and functional benefits of windows without creating a large energy leak. Researchers at Sage Electrochromics have been working on their glass product since 1989 when the company was launched as a technology spin-off from Rutgers University. In 2005, Sage opened its first manufacturing facility, and it has plans for an additional, larger factory.

Vice President of Marketing Lou Podbelski says Sage’s technology makes windows more energy efficient. Sage glass has a five-layer metal oxide coating. When a small voltage is applied during the “clear” state, the glass darkens as lithium ions and associated electrons transfer from the inner-layer electrode to the outer-layer electrode. In the dark state, the glass blocks 98% of solar radiation. Reversing the voltage reverses the process, and the glass un-tints.

“Our product allows you to bring in maximum light on a gloomy day,” Podbelski says. He thinks the product will gain acceptance beyond its early-adopter customer base and will someday replace everyday window shades and blinds. “Once energy passes through the glass and hits the shades, it’s already in the building,” he points out, “and so you still get a problem with heat gain.”

“What is the most environmentally benign building material? Anything that you do not have to make or throw away.”

REGULATING HEAT also can be achieved with dynamic materials that are making an appearance in new forms of interior wallboard. BASF and DuPont have separately introduced wax-based technology for plaster or gypsum boards. When a room made of the boards reaches a temperature threshold in the daytime, wax encapsulated in them melts. Excess energy from the room is absorbed during this phase change. When the room cools again in the evening, the wax hardens and releases the stored energy as heat.

BASF claims that its wax-containing Micronal plastic microcapsules dampen heat variability by 7%, reducing energy costs and making building occupants more comfortable. DuPont introduced its Energain wall panels at a Paris tradeshow in 2006. The wax in Energain is trapped inside a polymer matrix and sandwiched by radiant aluminum sheets, which the company claims makes installation easier.

High-performance chemicals are necessary for green buildings, but they may also carry a human health cost, warns Paul Bogart, programs director for the Healthy Building Network, an advocacy group. “In the early days of the movement, buildings became much more energy efficient, but we saw a drop in indoor air quality. We do need CO2 reductions for obvious and good reasons, but I would hope we would not swing back to the detriment of health,” he says.

To avoid a return to the days of “sick building syndrome” the Healthy Building Network encourages architects to plan for proper ventilation and reduce the use of materials that contain polyvinyl chloride, related plasticizers, and volatile organic compounds, or VOCs.

The efficiency-health trade-off is most acute for compounds that seal together the pieces of a building envelope and protect it from weather, wind, and sun. These adhesives often emit VOCs.

Manufacturers of materials and building components are mitigating VOC emissions. An example is Kemper Systems, a producer of reinforced waterproofing and roofing membranes, which usually require VOC-laden solvents to apply. In March, the company introduced a solvent-free product that combines a polyester reinforcement fleece with an odorless, two-component urethane. The new membrane has a VOC level of less than 10 g/L, significantly lower than the standard maximum level of 200 to 250 g/L.

Kemper President Steve Cortazzo says low-VOC materials are important to his clients, and not just for air quality reasons. “The solvent-free ingredients mean we can avoid any business disruption or downtime. We can install the membrane while the business is in operation.”

Another company that’s keeping an eye on VOC emissions is silicone chemistry expert Momentive Performance Materials, which makes prepolymers that go into adhesives and sealants for the building industry. “The trouble is getting high performance and keeping VOCs low at the same time. You need the adhesion, tensile strength, and speed and ease of application” that traditional formulations provide, explains Bruce Waldman, global marketing manager for the firm’s prepolymers division.

Momentive created low-viscosity liquid versions of its Spur prepolymer that do not require any added solvent. After it is cured, the silylated polyurethane resin becomes a stretchy elastomeric solid. Company researchers found it especially difficult to locate a lower VOC version of the organofunctional silane commonly used to form a chemical bond between the sealant and window glass.

Cut Once Home builders install structural insulated panels under the roof to reduce solar heat gain.

MATERIALS MAKERS like Momentive will likely be rewarded for their trouble, according to a recent McGraw-Hill Construction survey, because “green building is now a multinational global-level phenomenon.” More than half of builders said they will be building green 60% of the time by 2013.

The survey also showed that just like for other performance materials, the next frontier for green products will be Asia and other emerging markets. Although green buildings have a small market share in Asia today, growth rates are faster than in the U.S. or Europe.

Construction has entered tough times, however. The global growth rate of new construction dropped to 3% in 2007 from 5% in 2006. At a McGraw-Hill conference in Washington, D.C., last month, Rick Fedrizzi, chief executive officer of USGBC, told builders that he expects new construction to slow dramatically. He said the majority of new work will be in retrofitting existing buildings for energy efficiency and advised builders to study new LEED standards for existing structures.

Yet retrofitting a building may be the greenest option of all, says 7group’s Boecker. “What is the most environmentally benign building material?” he asks. “Anything that you do not have to make or throw away. The best environmental choice is to renovate an energy-hog building in an urban context.”

When the market rebounds, Kemper’s Cortazzo thinks, green building will still be the priority. “More and more, the criterion for building activity is green. It’s to a point where you have to make a choice in your business. It may be more expensive, but when the recovery comes, that’s what our customers will be looking for.”

And Lstiburek will still be insisting on energy efficiency as the yardstick for green. “To be green, buildings have to save energy. It’s a measurable impact, as opposed to just using recycled bamboo,” he says. “All of a sudden, green is becoming serious and growing up. It is a huge shift in how buildings are designed and constructed.”

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Chemical & Engineering News
ISSN 0009-2347
Copyright © 2009 American Chemical Society

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