Green on the Inside
January 01, 2007
Appeared in Consulting-Specifying Engineer
In the past, office buildings that touted a green engineering design were only built in places like California and Oregon. In those days, building green was something hippies did—not cost-conscious building owners. But that's all changed.
“Green building is emerging as the standard,” says Scott Frank, partner with New York-based Jaros, Baum & Bolles. “Today, almost all owners will, at the very least, explore making their buildings LEED®. Those that don't are in the minority.” Frank is referring, of course, to the U.S. Green Building Council's Leadership in Energy and Environmental Design certification system for rating a building's level of sustainability.
And what's more, engineers say, owners are choosing to include more individual technologies in a single building—which means that engineered systems are a major driver in the green movement.
“It used to be more common to find a project that singled out one highly visible 'statement' technology and just bolted that on to an otherwise conventional building,” says Steven Turner, managing director of CTG Energetics, an engineering firm with offices nationwide. “Now, you'll walk into an office and it'll have underfloor displacement, radiant heat and high-performance glazing in the windows. It's exciting when you're seeing half a dozen technologies right in front of you.”
Ironically, as the green movement grows, engineers are reviving some unfairly jettisoned old ideas and finding new ways of approaching the design process. The result: some amazingly innovative office buildings that are easy on the Earth and on the owners' bottom-lines.
An integrated approach
If owners want green design to truly be a long-term cost-saving, energy-efficient choice, engineers know that different technologies and systems must complement one another.
All it takes is some up-front teamwork—and a little help from the computer. When New York-based Syska Hennessy began working on the EPA Region 8 headquarters in Denver, the team began the design process by working with architects and looking at all of the different engineering systems as one giant machine. Syska Hennessy's director of sustainable design and high-performance building technology, David Callan, says that this early partnership helped the firm choose the best systems and alternatives for the building by taking into account its unique structural aspects and finding what worked best in that climate, on that site and in that architectural design.
Energy modeling software also played a big role in the development of EPA Region 8's overall green plan. Thanks to this software, owners clearly can tell how cutting one technology might affect the whole operation of the building.
Other engineers also stressed early integration of the various systems, and of these systems to the building itself. “Instead of the architects designing a building and then handing it off to engineers to figure out the systems,” Turner says, “we're seeing a more interactive process where the interrelatedness of the systems and the shell are being recognized from day one.”
The bottom-line here is the bottom-line. Research has shown that a highly integrated, interactive design plan for engineering systems is the best way to be green and save money. Callan cites the most recent GSA LEED Call Study as evidence: “It basically says, if your team is integrated from the beginning and you're designing the building to do all the right things as a team, then achieving LEED can save you money, or at least be a wash,” he says. “But, if you're just doing business as usual and have people running around chasing LEED credit after the fact, then it will actually end up costing you more.”It's people!
When it comes to green trends, there is another huge factor driving the movement besides energy codes: “Energy consumption cost per square foot is miniscule to the cost of the person in the space,” says Scott Jordan, a product marketing manager with Palatine, Ill.-based Schneider Electric. “If they aren't happy, they aren't productive.”
In fact, the link between workplace comfort and employee performance has been extensively documented, most recently by the 2006 Gensler U.S. Workplace Survey, which found that almost half of the office workers surveyed would put in an extra hour each day if they had a better working environment.
One way to improve how workers feel about their offices is to design the building to incorporate daylighting. Unfortunately, even though most people prefer natural light to artificial lamps, slapping more windows on a building isn't exactly a great thing—for energy efficiency or human comfort. “If you aren't careful, daylighting can create spaces where glare makes it impossible to work,” says Mike Hatten, a principal at SOLARC, Eugene, Ore.
To balance these concerns, engineers have turned to full-scale live models. For example, when designers began planning the New York Times building's daylight system, they enlisted the Berkeley National Laboratory to build a 4,500-sq.-ft. mock-up where they could test hardware and technologies in a real-life setting. The result is a state-of-the-art system that reduces lighting energy use by 10% to 60%, depending on the areas of the building. At the same time, the system reduces glare using a system of mechanized, automated shades that adjust for the time of day and amount of light. On other buildings, engineers reduce glare by specifying glass with improved glazing technology, such as the electrochromic glass manufactured by Sage Electrochromics, Faribault, Minn. SageGlass can be instantly tinted to allow only 3.5% visible light with the push of a button, so workers can choose which windows are causing problems and eliminate the glare, while leaving other windows clear for light and view.
Unfortunately, people also can ruin a perfectly good lighting design by using it or the office space in a way the engineer and owner hadn't anticipated. And re-arranging a hard-wired system can become prohibitively expensive. However, a solution to this problem may be on the horizon. Created by Herman Miller, Zeeland, Mich., and energy consultants The Weidt Group, headquartered in Minnetonka, Minn., the soon-to-be-released Convia is a “control system for the controls system,” which allows for instant reconfiguration. “What it allows you to do is extend design into occupancy,” says Weidt Group partner David Ejadi. “You can plan all the controls, daylighting sensors and everything, and once people move in and start doing what they do, you can adjust the system to their needs—without paying for an electrician.” By just pointing the wireless wand at a daylight sensor, you can move it on a track and effectively re-wire it.
HVAC goes alternative
A major factor linking green design and worker comfort is indoor air quality. Syska Hennessy's design for the EPA Region 8 headquarters makes use of an innovative solution: dual-path HVAC. This system uses a dedicated outside air path to provide ventilation and humidity control separate from the sensible loads. By being able to separately control these factors, operators can keep workers more comfortable while eliminating moisture control and mold problems. The system allows EPA Region 8 to have constant ventilation, ensuring that there is always fresh, healthy air in the building.
Callan says the dual-path system is just one of a growing number of options available to engineers who want to get away from forced air systems that have been the norm since the 1950s. “There's nothing wrong with conventional HVAC,” he says. “There's very little risk, but you won't get any of the energy and cost-saving benefits either.”
These alternative HVAC technologies include older ideas that are seeing a resurgence, such as condensing boilers and ground source heat pumps, and newer systems, such as underfloor air distribution and natural ventilation, that are becoming increasingly popular. Among these technologies, underfloor air distribution stands out from the crowd. The system of choice for high-profile projects like One Bryant Park and EPA Region 8, as well as in smaller buildings like CTG Energetics' Natural Resources Defense Council Headquarters in Santa Monica, Calif., and SOLARC's Banner Bank Building in Boise, Idaho, underfloor air distribution offers some major energy saving benefits. By introducing air at the floor level, warm air starts out in the occupied zone where it's needed most and moves upward (and toward the exhaust vents) as it cools. The system doesn't waste energy trying to maintain perfect air mixing. Here, natural air stratification is actually preferable. The system also requires less energy from the chillers because it would be too uncomfortable to force 50ºF air out at people's feet. Instead, an underfloor system achieves the same comfortable cooling effect with air as much as 10ºF warmer. Besides these features, underfloor air systems also have the potential to save owners money over the years as tenants change or offices are reconfigured. In addition, the system offers an increased level of individual, people-pleasing control. Workers easily can adjust the floor vents in their own workspaces, making them more comfortable, while the overall temperature and flow remain under the guidance of central operations. Many engineers say that there's a good chance that underfloor HVAC distribution, and raised floor system configurations in general, could become the norm for office building design over the next 10 years.
Alternative energy generation is another big trend in green office design, and here, progress is being led by building owners. “The tendency now is for project owners to be interested in options other than traditional grid power,” Turner says.
One impressive alternative energy source is the 5-MW cogeneration plant designed for One Bryant Park by Jaros, Baum & Bolles. The system uses an innovative new turbine, manufactured by Solar Turbines Inc. Called the “Mercury,” it's capable of using a wide variety of fuels, including natural gas, coal and biomass, and produces extremely low emissions levels, in the neighborhood of less than 9 parts per million (ppm) NOx, 20 ppm CO and unburned hydrocarbons. What's more, the cogeneration aspect allows the system to put waste heat produced by the turbine into good use—in winter, it provides the building's heat.
Another popular energy generation option, and one that's seeing resurgence after years on the backburner, is the photovoltaic system. The latest trend is to incorporate more flexible photovoltaic cells into shingles and other aspects of the building itself, says P.S. Reilly, president and CEO of the Athena Institute in Seattle, making solar generation (for heat and electricity) more a part of the integrated system than the old scabbed-on panels. At the forefront of this trend is the “smart glass” technology invented at the National Renewable Energy Laboratory. In smart glass, a window's tinting does double duty as a solar generator. “It lets some light into the work space and converts some light to energy,” Reilly says. “If they get it right, it'll be really, really cool.”
But, despite these innovations, some engineers say that building owners might be better off investing in green energy produced off-site. Owners can lock in long-term contracts with wind power farms—a deal that gives them three benefits for the price of one. “You're getting a low-impact energy source for your building, but you're also locking in a price that serves as a hedge against fossil fuels,” Turner says. “And, you're enabling the further development of wind power, because those farms will reinvest your money into new wind turbines.
But, Callan says, many owners ignore this option in favor of putting a flashy demonstration technology into their buildings. Callan also says that frequently these systems don't really produce enough power for them to make sense. He argues that if you want real environmental impact and a real economic impact, you're much better off buying power from a windfarm. “That way, your commercial dollars are really supporting a greater good,” he says. “Of course, it's not as sexy, but it makes a lot of sense.”