A Bullish Investment in the Future

It was during a televised broadcast of the 1971 World Series that Merrill Lynch debuted its famous "We're bullish on America" ad campaign. Thirty years later, the financial giant continues to pursue this same spirit, with a new office campus that features aggressive implementation of energy-efficient engineered systems and displays an optimism toward the future.

12/01/2002


It was during a televised broadcast of the 1971 World Series that Merrill Lynch debuted its famous "We're bullish on America" ad campaign. Thirty years later, the financial giant continues to pursue this same spirit, with a new office campus that features aggressive implementation of energy-efficient engineered systems and displays an optimism toward the future.

And much of the credit for this bullish approach to engineering design goes to Kling, the Philadelphia-based A/E firm that was responsible for the design of all engineered systems for the campus. For this effort they have garnered a CSE 2002 ARC Award.

"Merrill Lynch wanted its new campus to be a model of energy efficiency," says Kling's project director Tom Reed, P.E. "For the most part, we followed the LEED [Leadership in Energy and Environmental Design] model, even though we weren't applying for LEED certification."

Strategically located in Hopewell Township, N.J.—about 40 mi. north of Philadelphia and relatively close to other Merrill Lynch sites, including the firm's global headquarters in New York City—Merrill Lynch's Scotch Road campus boasts 1.2 million sq. ft. of net space that provides corporate offices suitable for technology-driven management teams.

Work on the project began in January 1999 and was completed in September 2001. The campus has 12 buildings in all, grouped into four clusters of three buildings. Each cluster consists of a pair of office buildings grouped around a two-story assembly hall, which has amenities such as dining areas, training and meeting rooms, fitness center and attached parking garage.

Minimizing energy

A major part of the project story is the design-phase consideration of energy-efficiency strategies and long-term operating costs. The former was a special priority for the consulting engineers, who in the design phase, schemed a number of alternatives—not only for the mechanical systems, but also for all other engineered systems. These plans were then filtered through life-cycle cost analyses to forecast their economic viability.

In the end, designers specified a cooling system that uses both chilled water and ice storage, making possible a more uniform power-demand profile. To complement this hybrid system, a low-temperature, variable-air distribution scheme was implemented, further reducing energy consumption by decreasing the primary airflow rate, hence, the associated energy consumption from supply and return fans. Depressed supply air temperatures also have the effect of extending the economizer mode, which means that the ambient temperature is between the supply-and return-air temperatures for a longer period of time.

This combination of cooling technologies, of course, was implemented by the design team with the assumption that deregulation of the region's electricity markets will translate into a scenario where demand charges will rise faster than power consumption charges.

For both heating and cooling, a distributed strategy was selected. Each of the campus' four building clusters has its own self-contained mechanical systems, with both cooling and heating plants located in each cluster's assembly hall basement (see figure, p.38). Electric centrifugal chillers—using refrigerant R-134a, with a zero ozone depletion potential—generate low-temperature glycol for freezing ice during evening hours when energy costs are lower. Ice, in turn, is melted during the day to generate chilled water during high-cost peak hours.

Other chiller options were explored, but technologies didn't always gel. Take, for example, natural gas-fired absorption chillers. Energy simulations conducted as part of the life-cycle cost analyses proved that absorption chillers would supply the necessary heating hot water while reducing boiler quantity. However, the the system's suppressed chilled water temperature was at the low end of the range of absorption chiller's capabilities, making it a bad match.

Maximizing dollars

Life-cycle forecasting was critical as cost, of course, was always at the forefront. In fact, one might assume it was even more important on this project as the use of innovative technology—especially in unusual combinations—must surely result in higher first costs. On the contrary, explains Paul Lewis, P.E., and lead mechanical engineer on the project. He says designers were able to realize substantial first-cost reductions, for example, knocking down chiller plant size by 40%. This downsizing alone, further allowed the team to reduce the need for on-site power generation.

Specifically, by utilizing chilled water from ice storage as standby chiller capacity, the facility can ride through a two-hour chiller loss.

"We can simply pick up one chiller on a generator instead of two," says Lewis.

Chilled water from ice storage also serves for emergency cooling to various air-handling units (AHUs) as well as the facility's computer technology loop.

To achieve even greater energy efficiencies, notably by facilitating the use of variable-speed pumping, the chilled-water distribution system is based on a primary-secondary configuration. "Variable-speed pumping allowed us to supply only the amount of chilling that is needed," says Lewis.

Similarly, air delivery was also contemplated with the notion of maximizing energy-efficiency. Specifically, air is distributed by AHUs located in the attic spaces of each building. The units distribute air to fan-powered variable-air-volume (VAV) boxes, which regulate supply air to zones to meet room temperature setpoints.

AHUs on each floor of the office buildings are interconnected. This allows for the operation of the minimum number of units during evenings, weekends and other periods of partial occupancy, thus allowing fans to function in a more efficient operating range.

"The interconnection of AHUs on each floor allows for versatility," adds Lewis. "Direct digital controls (DDCs) can pinpoint where the occupants are by light usage, and the looped ductwork delivers air as needed."

While the primary system described thus far suits core office spaces, separate provisions were needed for special areas. For example, because air distribution is through ceiling spaces, raised-floor technology spaces—primarily for power and communications cable distribution—are served by supplemental air-conditioning units.

Also, all perimeter zones are positively pressurized. Those with large glass areas, such as the common-use areas, are heated by hot-water baseboard radiation, while perimeter zones with smaller glass areas are heated by VAV box-mounted hot-water reheat coils, which regulate supply air temperature to be proportional to the heat loss through the glass.

As for the heating side of the mechanical systems, once again energy efficiency was a priority. Heat is supplied by dual fuel-fired boilers that supply hot water to preheat coils, reheat coils and miscellaneous heating elements. Conference rooms and similar spaces requiring reheat in the summer have electric heat coils. This strategy allows the heating hot-water boilers to be de-energized when they would otherwise operate, even at a low-load, low-efficiency condition.

Air quality—indoors and out

Of course, an ongoing engineering debate is the ability to achieve energy efficiency yet maintain high IAQ. Despite this perceived conflict, Kling was committed to providing a high degree of IAQ as it was a way it could meet the LEED goals it had set for itself.

The team optimized IAQ by:

  • Using fan-powered VAV boxes, which mix supply and plenum-return air and elevate supply-air temperature, minimizing drafts and maintaining consistent air motion.

  • Locating AHUs in attic spaces vs. intakes near parking lots and loading docks, lawn maintenance equipment and chemicals, averting infiltration of noxious emissions.

  • Installing fiberglass acoustical insulation in a way that prevents its exposure to the airstream.

  • Monitoring the carbon dioxide concentrations of supply, return and outside air. This data, in turn, allows the building automation system to reset the minimum outside airflow rate. Furthermore, due to the longer duration of the economizer mode, the scheme allows for the introduction of more outside air to dilute the concentration of indoor air pollutants.

As far as the latter, reducing emissions of various equipment was another important consideration. For example, heating hot-water boilers use induced flue-gas recirculation to redirect flue gases into the combustion chamber to maintain a flue gas exit temperature at a point that minimizes NO x emissions.

Beyond mechanical to BAS

Mechanical systems are a big part of the project's success story, but other engineered building systems—notably the electrical and building automation systems—also play key roles.

The BAS works on an individual cluster basis, each capable of standalone operation. However, each unit provides alarms to the central building operator workstations.

Other significant highlights:

  • Fan-powered VAV boxes are equipped with heating-coil control so that during nighttime setback, the fan and heating element in each box—either the electric or hot water—cycle to maintain the setback temperature, without operating the larger supply AHUs.

  • Control systems for the supplemental air-conditioning units that supply the raised-floor technology spaces have electronic factory-installed control systems with monitoring by the BAS.

  • Lighting systems are controlled by timeclock-based contactors—through the BAS—in both open and enclosed office spaces. Occupancy sensors are used in restrooms and conference rooms to conserve energy use. Exterior lighting is photocell- and timeclock-controlled.

Power to the campus

The design team's "green building" agenda was realized in the electrical design as well. Power is supplied by a looped 26.4-kV distribution system with local (building-level) voltage reduction. In conjunction with the ice-storage chilled-water system, the power system places the facility in a good position vis-à-vis the deregulated electric market for several reasons:

  • It supports the facility's high-uptime goal because a portion of the loop can be bypassed if damaged or down for maintenance, without disruption of service to the buildings.

  • Utility metering on each service at the switchgear are totalized to offset demand peaks.

On the project, power quality is as important as reliable power, due to the large amount of computer-driven technology space on the campus. Transient voltage surge suppression capability is available for all buildings, as are shielded isolation transformers to handle higher levels of harmonic current and minimize sensitivity to electrical noise.

Further protection from power events is provided by an uninterruptible power supply system. On-site emergency generators also serve life-safety systems, certain office area receptacles and HVAC equipment, as well as all loads in the cluster technology centers.

And like the mechanical system, the ultimate power system went through a number of iterations, several worth noting, as given the right conditions, they may be reconsidered for future use:

  • An on-site substation. To be owned either by Merrill Lynch or by the electric utility, the station would supply power at 69 kV.

  • Cogeneration of steam, chilled water and power. This was considered but discarded due to cost. Again, planning has allowed for its inclusion when the technology's economics improve.

  • Hybrid natural gas/power. Balancing annual energy costs between the two creates flexibility to shift as one increases in price relative to the other.

Campuswide networks

Finally, no modern business facility is complete without a solid voice-data-video scheme.

In this project's case, it was even more important, as Merrill Lynch decided it wanted an IP-powered virtual call center on the campus. The call center enables the firm to make contact with clients virtually anywhere in the world via voice, data or video. And the company envisions an eventual move beyond automated voice routing systems to relying on multiple media to provide a more personalized level of service. Therefore, the VDV systems must be actively maintained around the clock.

The system starts with its backbone which connects all systems, including building automation, communications, fire alarm and security. The central infrastucture network is facilitated by 6-in.-high raised floors installed throughout most occupied areas in the complex. This also makes future workstation cable routing easier.

Besides an extensive amount of fiber-optic cable, a further of degree of robustness is achieved by redundant main feeders routed in different paths to telecommunications closets, minimizing the risk of single points of failure.

Teamwork

Successful delivery of a complex, high-uptime, multi-building facility demanded a high degree of interaction among owner, the A/E, other consultants and the construction team. This goal was further complicated by the fact that Merrill Lynch wanted an aesthetically pleasing environment that would attract and retain high-performance employees.

Kling's engineering team not only helped the firm realize its programmatic and budgetary goals, but the firm's long-term planning and careful life-cycle cost analyses will make it possible for Merrill Lynch's "green" rural campus to continually adapt to the future, optimizing environmental conditions for its employees for years to come.





No comments