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Stacking Technology for Energy Efficiency


Holistic approach provides optimal performance for net zero retrofit project

Humanscale facility in Piscataway, N.J., was retrofiteed with solar panels and Solatube daylighting system.Humanscale's Director of Sustainability Jane Abernathy's vision to have Humanscale's Piscataway, N.J., 110,000-square-foot facility retrofitted to improve energy efficiency, with an ultimate goal of a net zero carbon footprint.

Humanscale is the premier designer and manufacturer of ergonomic products that improve health and comfort at work. The company, based in New York City, has award-winning office solutions including self-adjusting seating, sit/stand desks, monitor arms and task lighting, which inspire movement and support the user in every posture. Humanscale also has a strong corporate sustainability philosophy which states "Everything we do has an impact. We're aiming to make it a good one."

When she put the solar panel project out to bid, one company came back with ideas for a "stacked" technology approach: Pfister Energy, out of Hawthorne, N.J., a full-service energy company that specializes in renewable energy systems.

As Wayne Pfisterer, president of Pfister Energy, explains, "Although the initial bid was only for solar panels, we took a holistic approach to the facility by looking at which technologies we could 'stack' for optimal performance. We looked at things like the client's objectives, ROI/payback period, state incentives, permitting, engineering and so on. From there we made recommendations on the right mix of technologies for Humanscale's facility. Fortunately, [Abernathy] was open to our ideas."

After evaluating Humanscale's facility, Pfisterer discovered that the roof had about only five years left before it would need to be replaced, so they started there. "The existing roof was a black tar surface that retained considerable heat, thus making the facility hotter. We specified a 2-inch insulation board with a white membrane roofing system with reflective properties, thus providing a much cooler environment." The company also specified a 775 KW solar array which comprised 2,585 solar panels. The system generates enough energy to offset the facility's electrical usage annually.

Humanscale's solar panels generate the power that the facility uses during the day. During weekends and low-usage times the excess power flows out to the power grid with the local utility (rather than storing on-site, which would require large battery cells). If additional power is needed, the company can access the grid much like a big battery system. At the end of the year, Humanscale and Pfister Energy will review the energy consumption and make any adjustments.

Pfisterer also decided to introduce company executives to Vista, Calif.-based Solatube International Inc.'s Daylighting Systems, which integrate easily with solar panels and would help Humanscale achieve energy savings, a more productive work environment and reduced ecological footprint, all driven by its corporate sustainability philosophy and Abernathy's vision. "We knew that the production area would be dramatically improved by having natural light from the Solatube products to help employees with product assembly," Pfisterer said.

The project was originally specified with 300 Solatube 750 DS units. When Solatube International's new SkyVault M74 Series was introduced, the project stood to benefit tremendously from the use of the much-larger SkyVault units. SkyVault units are designed for large spaces, particularly those with ceiling heights of 18- to 40-plus feet.

SkyVault products require fewer roof penetrations (since fewer are needed to daylight a given space), and increase daylight output, which decreases lighting costs. The project used 87 SkyVault M74 with Amplifier units-the Amplifiers redirects daylight to the visual task plane.

While the initial goal of using daylighting systems was lighting energy savings, the daylighting noticeably impacted quality control in the production area. Of the 110,000-square-foot facility, approximately 38,500 square feet was daylit using Solatube SkyVault units, with the remaining roof area over storage racks dedicated exclusively to PV panels.

"An unexpected benefit is that the Solatube Daylighting Systems reduce shadows and show color more accurately, so workers can now detect small flaws they weren't able to before," says Willy Duran, production supervisor at Humanscale. "It's positively impacted product quality."

"The reaction among Humanscale employees is that they love the daylight. It's very apparent to them the difference in brightness, quality and color of light from one side of the facility to the other. They like their work environment better," according to Tim Neher, Humanscale facility maintenance supervisor.

"With the Solatube units, we don't have task lighting hanging down over each production area," Neher adds. "You can see from one end of the floor to the other. It's a much cleaner, more open space."

"During summer months, when power demands are at their greatest in the hot weather, the energy grid is susceptible to brown- or black-outs. One of the great things about the Solatube SkyVault units is that no matter what is happening with the power grid, daylight continues to flood into the space during the day, even during a black-out," Pfisterer says.

Additionally, Pfister Energy added a new LED lighting system, including daylight harvesting and motion control systems. Pfisterer estimates the payback periods as:

  • Solar panels: 4 years
  • Solatube Daylight Systems: 7 to 8 years
  • LED lighting: 1 year
  • All of the above combined: 4 to 4.5 years
  • All of the above combined with the new roof: 5 years

Phase two of Pfister Energy's "stackable energy approach" for Humanscale will likely include rain harvesting and containment tanks for use with irrigation and plumbing.

Pfisterer sums up by saying, "The Humanscale team has embraced our vision of stackable solutions by incorporating multiple technologies and optimizing them for their facility. In America, we have to build energy plants and infrastructure for peak power. In many areas we have an antiquated electrical grid that is inefficient. Projects like this produce onsite power that is not only much more efficient, but can also offset streams on the electrical grid at critical times."


Neall Digert is vice president, product enterprise, at Solatube International Inc., Vista, Calif., the worldwide manufacturer and marketer of tubular daylighting devices. He can be reached at To learn more visit