Green Economics

When managers at Madison, Wis.-based Affiliated Engineers, Inc. (AEI) decided it was time to build a new headquarters, they saw an opportunity to practice the sustainable-design principles they've been preaching to clients for years. In fact, in staying true to the good engineering practices mantra, planners envisioned this new facility as an integrated unit rather than a collection of disparate systems. For example, their plan recognized connections between such seemingly unrelated elements as window glass and air-handling units—a relationship that ultimately resulted in a more efficient operation and a less costly building.

Also, since AEI would occupy this space for years to come, maintenance and operations came to the forefront as a key component of the client program. For instance, a priority was placed on indoor comfort to increase the effectiveness of the engineers who would occupy the space. Another significant item on the "wish list"—from an engineer's perspective—was the emphasis on commissioning from the earliest stages—a decision that has helped AEI capture $30,000 in annual energy savings.

To achieve these results, the engineer had to work more closely and much earlier with the project's architect and contractor, Flad & Associates and Vogel Brothers, respectively, creating a truly integrated design-build team.

While this was clearly very much an M/E/P engineer-driven project, it wasn't a case of the kid being let loose in the candy store. In developing its new headquarters, AEI faced the same conundrum encountered by any building-design firm interested in shaping its own space: performing the dual role of designer and client.

Management wanted the new headquarters to showcase sustainable principles, but their interest in maintaining budgets was every bit as strong as that of outside clients. Instead of opting for one or the other of these seemingly diametric goals, AEI decided to do both.

"Some of us acted as client and some of us acted as designers," said Carl Stumpf, an AEI principal and the job's project manager. "So we spent a lot of time discussing goals and philosophies."

Furthermore, AEI desired to document this experience as an object lesson for others. "A lot of our clients wanted to know if sustainable design could be done without costing more," said Karen Dettinger, another AEI principal.

Dettinger, who served as the "client" on the project, noted that one of her major goals in this role was to ensure that design decisions wouldn't result in higher operating costs once AEI occupied the structure.

To make this work, AEI pulled in Flad and Vogel Brothers, a pair of companies that understand the benefits of early and active team involvement. "Flad and AEI work on a lot of projects together," said Flad designer Randy Schmitgen. "We like integrated design, and that's how we focus our efforts. So we try to set up our projects with that in mind."

The team committed to AEI's theory of affordable sustainability early on but felt a somewhat scientific methodology was needed to gauge the success of the project. To establish a baseline for what construction and operating costs might have been had they used a more traditional design, the team referred to a similarly-sized office that one of the team members has recently completed (see "Proving Sustainability's Bottom-Line Benefits," p. 44). Although the results are perhaps more anecdotal than truly scientific, they do document how good design can be both environmentally friendly and economically beneficial.

The U.S. Green Building Council's Leadership in Environmental and Energy Design (LEED) guidelines served as another baseline. AEI is currently applying for LEED certification, but certification was not a primary goal. The LEED process helped the team better understand the interdependence of various building elements—and building-team members—which is crucial to this approach.

For example, maximizing natural light was a major architectural driver to both boost worker comfort and minimize artificial lighting requirements. However, AEI engineers wanted to keep heat gain—and the resulting cooling needs—to a minimum. The solution: A two-tiered approach involving a combination of both "view" glass and "daylight" glass.

View glass allows clear views out of the building but limits visible-light transmittance through its surface to 18%. Most fenestration in the building features view glass, but it is complemented by a narrow band of daylight glass that runs above these larger panes. Daylight glass has a visible-light transmittance of 38%, which allows a stream of daylight to flow deep into the building core. This low-transmittance glass is more expensive than standard material, but the reduced heat gain, refracted by the windows, allowed engineers to specify smaller air-handling equipment. In fact, the savings from downsized AHUs paid for the more expensive glass.

The same combination of efficiency and comfort that went into designing the daylighting was also key in the overall mechanical plan for the building. Although many of the design tactics AEI used on the building have become accepted practice over the past few years, designers added some new and untested innovations. Specifically, zoned variable-air-volume (VAV) boxes deliver treated air to interior spaces, with hot-water reheat coils kicking in during the cold Wisconsin winter. Heating and cooling setpoints are reduced during evening and weekend hours. This zone-based design allows setpoints for computer-server areas to be reduced even further during low-demand times, with a transfer fan pushing excess heat into unoccupied office spaces.

Controls for this equipment are equally cutting-edge. Wireless thermostats help occupants address localized temperature-control needs that can shift significantly throughout the seasons. Receivers are located in each zone's VAV box, allowing thermostats to be relocated at will within a zone to ensure that any extremes are addressed. For example, in the summer, Stumpf noted, the thermostat controlling his area works best when placed in his office. But during cooler months, it works best when placed in an adjacent conference room.

Advanced carbon dioxide (CO2) monitoring is another feature that furthers comfort and productivity goals. In this LEED-recognized tactic, sensors are located on each floor and also at AHU intakes to ensure that fresh-air supplies meet occupant needs. If internal CO2 levels climb significantly above external readings, the system boosts fresh-air supplies. "We've been using it a fair amount with our other clients," said Mike Walters, AEI's sustainable design specialist. "It keeps people awake in the afternoon."

Additional indoor-air quality measures include the use of high-efficiency filters that meet minimum efficiency reporting value (MERV) 13 standards. These units are 80% to 85% efficient—compared to the 60% to 65% levels of standard units. In this case, the filters were marginally more expensive than standard units, but according to Stumpf, they were selected with an eye toward meeting LEED requirements.

Along a similar vein, AEI incorporated a substantial flush-out period to address any IAQ problems that might arise with the outgassing of furniture, carpet and other finish materials. Though low toxicity was an important factor in finish selection, AEI still believed a flush-out to be an essential pre-occupancy effort. This was no mean task, as Wisconsin's cool temperatures—even in March—meant the building had to be closely monitored to ensure that systems weren't damaged during the period in which 100% untreated fresh air was allowed to flow through the offices. According to Vogel Brothers Project Manager Dan Carlson, inside temperatures, at times, dipped into the 20s.

This exercise was no simple task, either, and Carlson emphasizes that it had to be planned for from the outset of the project, as it would have a significant impact on construction and occupancy schedules.

"We knew there would be a two-week period when everything had to be done, even though the client wouldn't be able to occupy the space," said Carlson.

Proper planning was equally important to the team's success in commissioning the building. AEI served as its own agent and established requirements prior to finalizing project budgets—a key factor, according to Carlson, to ensure estimated costs matched actual design specifications.

During this process, adjustments were made to equipment setpoints, boiler operation, lighting controls and reheat functioning. These commissioning efforts cut energy demand by 50%, which translated to about $30,000 in annual savings, Walters said. In other words, the $15,000 commissioning cost was paid for in just six months.

Although largely successful at incorporating a range of green technologies—and finding additional savings therein—AEI's design was not completely bug-free. As one example, the time-clock-controlled lighting system proved problematic, according to Stumpf. The firm is currently retrofitting photosensors to help address the issue. Wired switches that provide intermediate—not just on/off—settings are also being incorporated to allow for a range of personal preference.

But being able to experience such problems firsthand provides the firm with a valuable opportunity to learn, rather than learn the lesson on another client's project via a lawsuit.

"We don't want to experiment on our clients," Stumpf said. "But some of the people that Mike [Walters] works with have been using the building as kind of a lab [for sustainable technology development]."

Would they do it again? Yes, said Stumpf, as the experience not only gave AEI the chance to create a space that specifically meets its needs. It also expanded its knowledge of affordable sustainable technology—something they can now take to the bank.