Volume 43, Issue 3 - March 2008
To Zero By ’Fifty
by Megan Headley
The Energy Independence and Security Act of 2007 was signed into law in December 2007, linking the next generation of commercial buildings to zero-net-energy. Among the new law’s provisions is an initiative to develop technology and policies that will allow 100-percent of all commercial building, new and retrofit, to be zero-net-energy by 2050.
A building that uses no energy? Not quite. According to the act: “The term zero-net-energy commercial building means a commercial building that is designed, constructed and operated to a) require a greatly reduced quantity of energy to operate; b) meet the balance of energy needs from sources of energy that do not produce greenhouse gases; c) therefore result in no net emissions of greenhouse gases; and d) be economically viable.
The United States Department of Energy’s (DOE) deputy assistant secretary for energy efficiency, David Rodgers, says that zero-net-energy buildings use 70 percent less energy than conventional buildings and are able to produce enough electricity on-site or through storage to power the building through the rest of the day. According to Rodgers, integrating systems and looking at a building as a whole unit is critical in reaching this zero-net-energy goal. For example, the windows in the buildings impact the money spent on heating and cooling. “Windows, annually, are responsible for 3.8 quads of energy in the United States in the form of heating and air conditioning loads at a cost of more than $30 million,” Rodgers says.
The design and construction industries are beginning to develop paths to zero-net-energy, with some completed commercial projects already meeting this goal (see Zero-Net-Energy in Action on page 47). The glass industry certainly is involved in these endeavors. “The weakest link in the envelope is obviously the glass,” says Lou Podbelski, vice president of SAGE Electrochromics Inc. in Faribault, Minn.
And yet, glass provides many opportunities for both reducing energy usage in commercial buildings and, perhaps ultimately, for creating energy.
Reducing Energy Usage
“Before you can talk about things like photovoltaics (PV), or other energy sources can come to save the day, we have to make our buildings as energy-efficient as possible,” says Podbelski.
Many of the products available now are designed to reduce energy usage by reducing the amount of solar heat allowed in through the glass.
“Low solar heat gain coefficient (SHGC) is something that is widely available on the market right now,” says Serge Martin, vice president of marketing of AGC Flat Glass in Alpharetta, Ga. Martin notes that it’s important for commercial buildings to focus on reducing heat at all times—even more so than residential buildings that may utilize solar heat during colder months—because of the heat radiated by a higher density of people, computer servers, electric lights, etc. “I think the next step in insulating value is probably going to come from triple-glazed [units],” says Mike Rupert, director of technical services for Pittsburgh-based PPG.
John Lewis, technical director of the American Architectural Manufacturers Association, expects that “highly-efficient low-E glazing with gas filling” will become more commonly used to create zero-net-energy buildings. “Framing materials will be driven to provide less conductance to heat flow,” Lewis adds. Energy-efficient glass is critical because, although glass can be seen as “the weakest link” in a building, an increased use of glass provides its own benefits. “Some people say ‘just reduce the amount of glass’ but that doesn’t seem to be the right thing to do either because of the benefits of daylighting,” says Podbelski.
In addition to research showing the health and productivity benefits of using natural daylight, there are practical benefits. For instance, large expanses of glass mean fewer artificial lights. “That’s a double bang for the buck. If you can [increase daylighting] not only do you reduce the cooling cost but you reduce the use of artificial lights,” says Rupert. “Lights generate a tremendous amount of heat that has to be mitigated through HVAC systems, plus the cost of operating those systems.”
Lewis expects that more products will take advantage of daylighting in the future. “Active technologies that take advantage of natural daylighting will become more widespread. A good example of this would be lighting controls used in conjunction with increased use of skylights,” he says. Electrochromic windows—or electronically tintable windows, which change from transparent to opaque as necessary—are frequently mentioned in discussions of zero-net-energy buildings. These products, when coordinated with electric lighting, can help reduce peak energy demand anywhere from 19 to 26 percent, according to Podbelski.
“Given the dynamic nature of the product, based on the season or the time of the day, we can change our glass from a very clear state to a dark state,” says Podbelski. “That affects the SHGC.”
The dynamic products can reach a 0.09 SHGC. While high costs and additional installation steps keep the products from being prevalent currently, the technology is evolving. “Currently it’s more viable certainly for new construction because our first generation requires wires,” Podbelski says of the switchable products. However, he suggests that future generations may be powered using PV. Martin suggests that someday glass products in commercial buildings could even be used to assist in ventilation. He anticipates that active facades—“double-skinned facades where you have some sort of gap between two glass facades and you can circulate air during summer”—will be seen in the future. “In the very short term the products are there but maybe the design that we apply is not fully [realized],” Martin says. “Maybe in 20 years from now the technology will be more widely available and that could be an option.”
Martin notes that AGC has long been a supplier of extra-clear glass for solar modules, and is seeing tremendous growth in this area. “We see it growing consistently and year after year the cost of solar electricity is going down,” he says. According to Rob Struble, marketing communications manager of PPG, “As PV technologies advance, the day may come when solar energy can be harvested through regular spandrel and even vision glass without aesthetic interference.”
“There are technologies out there that need to be further refined,” Rupert says. “The low iron glasses that are out there for PV, anti-reflecting coatings to make sure every bit of the sun’s energy that strikes that surface is transmitted through it,” are some examples that he names. “Those are all things that exist today but things that can be further refined.”
Speed Bumps on the Road to Zero Energy
For example, Podbelski notes that his company has plans for future expansions of its facilities, which will increase the likelihood of “high-volume manufacturing to get the price down low enough where it makes sense” to specify more electrochromic units. “The barrier right now is the cost,” he says.
The same stands for PV, Rupert says. “PV will take off if we can get the cost down,” he says. “Cost reductions are going to come from all sources, be it the manufacturing, the components, the installation, how they harness and control that power, if the whole industry concentrates like they are.”
Martin agrees. “Maybe in 20 years from now the technology will be more widely available and that could be an option,” he says. “Cost still could be a concern.”
However, reducing the costs isn’t the only problem. Martin points out another cost-related issue that doesn’t involve the technology. “It’s the financial structure of the construction industry,” he says. “The one person who is investing in the building is not the person who will be paying the bill so … there are not a lot of incentives.”
Challenges such as these high costs will soon have to be resolved as the federal government has added pressure to race for zero. The timeline set in section 422 of the Energy Independence and Security Act of 2007 aims to have all new commercial construction be zero-net-energy by 2030 (see A Bill on Capitol Hill, page 48). But is that feasible?
“Well if I can look in my crystal ball … I would say it is feasible, but I think it’s going to need a little bit of incentives for people to do the right thing,” says Podbelski.
“We’re seeing that obviously with all the emphasis on going green—certainly the U.S. Green Building Council, the Leadership in Energy and Environmental Design system, all the talk about what we’re doing to our environment, greenhouse gasses—all this is fuel to push this trend into more of a reality. “I think that’s doable,” agrees Rupert. “I think certainly if the government can put some incentive into doing that for folks or industries that will help.” What type of incentives might lead this push toward going “greener” is still debatable.
Podbelski notes that higher energy costs will provide their own incentive. “I think we’re going to see more pressure in terms of prices going up for energy to make energy-efficiency and alternative sources of energy more viable,” he says.
Podbelski expects that government intervention will be a natural consequence of the demand for new energy sources. “We’ve seen this, particularly in the glass industry,” he says, using hurricane glazing as his example.
“All of a sudden we’ve had some bad hurricanes … lo and behold now [hurricane-resistant glass] is legislated and the cost of the glazing is much more expensive than what it was just a few years ago—but it’s all for a common benefit.” Others expect that now that green design and building has proven to be a lucrative endeavor the market will drive itself in the direction of zero-energy. “Nothing will drive it more than individual companies or players outside of government,” says Rupert.
He adds, “The government can help—we certainly don’t want it to impede.” Martin agrees that some boundaries from the government could be useful but it would be best to “let the industry play,” as he comments. “The market can take care of itself.”
Zero-Net-Energy in Action
Moreover, the energy-efficient building was a retrofit of an older building.
“This building was a concrete block that didn’t have almost any windows at all and part of getting the zero-energy is getting some daylight,” says Kim Swanson of EHDD Architecture in San Francisco, the firm that led the design process. Swanson elaborates, “On the south façade of the building we cut into the concrete for an opening of almost a whole wall of sliding glass doors.”
Skylights also have a role to play in increasing daylighting. “We cut a dozen or so skylights into the existing roof also to apply daylight so we could rely on daylight as much as possible,” Swanson says. “There’s also electrochromic glass on the east side. In essence, the electrochromic glass is fused electrically and it ‘closes or opens’ depending on whether there’s direct light on it.”
Swanson notes that high-performance glass was specified throughout the building and installed by TGM Commercial Glazing of San Jose.
A Bill on Capitol Hill
Section 422 requires that the appointed commercial director of the Office of High Performance Green Buildings establish the zero-net-energy commercial building initiative to reduce the quantity of energy consumed by commercial buildings and achieve the development of zero-net-energy commercial buildings.
The commercial director, working with the High-Performance Green Building Partnership Consortium (created by the bill), will conduct research and benchmarking on design and materials; offer technical assistance activities; provide training for “building professionals and trades;” and support state and local code-setting organizations in developing minimum performance standards that “recognize the ready availability of many technologies utilized in high-performance energy-efficient buildings.” The act also would develop separate incentive strategies for builders and purchasers, and landlords and tenants.
Megan Headley is the editor of USGlass magazine.